Coolant is still running too cold?

[dom14]

Hey Guys,

I'm trying to figure out what's going on with the coolant temperature in my GQ RB30 carby vehicle.
Stock gauge was showing lower than normal temperature for a while now.
I thought it's the dodgy gauge and decide to install an aftermarket one to get
a correct idea about the coolant temperature when the engine is fully warmed.

68 degrees celsius is as high as the temperature would go whether it's idling or driving on the road for about 15 minutes or so.
The aftermarket gauge is accurate as I tested it outside the vehicle today.
The gauge sensor location is T joint between LPG converter & the engine block.

I removed the thermostat and tested it separately. The thermostat open at around 74 degrees
the way it's suppose to work, and it doesn't open stuck.

I'm beginning to think the engine is not getting hot enough for some reason.

I'm assuming it is an issue, 'cos I believe fully warmed up engine temperature should be bit higher than 68 degrees, regardless of where in the coolant system I take the temperature from. I'm kinda pretty sure, whether I drive the vehicle for a longer period or not won't make any difference.

Can you please help me with some advice, tips, guides on how to tackle this issue?

Thanx in advance.

[garett]

is that the in or the out line? if it is from the converter expect it to be cooler, when gas changes state it get really cold.

my car has the same issue cant get it hot. sits about the same when i'm sittin on 100 lower if i slow down. most i have ever got was 1/3 on the gauge ( 3 rd gear foot flat up a hill for a long time)

i'm running a 77 deg thermostat.

i'm still looking for a solution as running too cold isn't good. but not as bad as too hot.
i prob suggest that you should of had a 82 deg thermostat for a petrol.

[the evil twin]

Your thermo is too cold... as garret said, put the hotter thermostat in.

[dom14]

is that the in or the out line? if it is from the converter expect it to be cooler, when gas changes state it get really cold.

my car has the same issue cant get it hot. sits about the same when i'm sittin on 100 lower if i slow down. most i have ever got was 1/3 on the gauge ( 3 rd gear foot flat up a hill for a long time)

i'm running a 77 deg thermostat.

i'm still looking for a solution as running too cold isn't good. but not as bad as too hot.
i prob suggest that you should of had a 82 deg thermostat for a petrol.

Hi mate,
It looks like I might have gotten the spot of the sensor installation wrong by the looks of it.
Please have a look at the diagram below and let me know if I got it wrong.

I didn't mark the direction of the water flow on the LPG converter/heater core water lines, 'cos I'm not too sure.

BTW, my statement "'cos I believe fully warmed up engine temperature should be bit higher than 68 degrees, regardless of where in the coolant system I take the temperature from.", is obviously incorrect.
Pardon my brain fog.(calorie controlled diet :) ). There's obviously a reason why the stock temperature sensor is installed at the coolant port on the cylinder head where the coolant comes out of and enter the top port of the radiator.

The reason I couldn't install the aftermarket temperature sensor at the right spot on the cylinder head is 'cos the sensor wire is tad short to reach there. So, I chose water lines towards the back of the engine where it comes out of the block.
I thought it might be a good representation of the water temperature where it comes right out of the engine block.

[kbchez]

put the sensor in the correct place and extend the wire to reach. You may need to install a genuine thermostate or at least the correct temperature range. To cold means more fuel will be used. As the ECU will think the engine is cold and needs more fuel. Been there done that.

[garett]

umm i'm not familiar with the set up that has been used for the gas converter. we usually put the converter in series rather than parallel like it is in your picture. (if your converter is too hot to hang onto after its been running shouldn't be a problem) but it does look like your temp sensor might be after the heater or converter so it will give a lower reading than actual. kbchez is on the money here even carby will use more fuel.

[dom14]

Hi Guys,
I put the sensor in the next T joint where I believe the inlet line for heater core/LPG converter as in the below diagram.
There's no improvement so far.
Idling temperature didn't go above 66 degrees, so it's kinda worse than before.
When I took off for a drive it went up to 68 degrees.
After I stopped at the supermarket for ten minutes and got back to the car, the gauge was
showing 71 degrees, which immediately went down to 66 degrees after I started the engine.

I can extend the sensor wire with another one, but I'm not sure that would affect the accuracy of the temperature reading, though I can get some idea about any discrepancy by putting the sensor again in boiling water to see how much the wire extension off sets the temperature reading accuracy.
I'll do that tomorrow and post the outcome.

The next temperature gauge controller kit I'm getting has the ability to calibrate the gauge, so extending the sensor wire won't be an issue with that. But, it's a good week away from arrival.

Thanx

[dom14]

put the sensor in the correct place and extend the wire to reach. You may need to install a genuine thermostate or at least the correct temperature range. To cold means more fuel will be used. As the ECU will think the engine is cold and needs more fuel. Been there done that.

No ECU atm. It's a carby. The existing thermostat is the stock nissan one, which I tested and it opens at around 76 degrees as it's printed on the thermostat. I think the thermostat is fine, and it's the correct range for RB30 engine, but I may have to do something about this. Either get a thermostat that opens up at a higher temperature or I need find the exact cause of engine's running too cold(assuming it is running too cold).

[dom14]

umm i'm not familiar with the set up that has been used for the gas converter. we usually put the converter in series rather than parallel like it is in your picture. (if your converter is too hot to hang onto after its been running shouldn't be a problem) but it does look like your temp sensor might be after the heater or converter so it will give a lower reading than actual. kbchez is on the money here even carby will use more fuel.

Thanx mate.
How does the carby burn more petrol when the engine's running too cold all the time?

[Robo]

Maybe your thermostat is sticking open.
The aftermarket temp sensor needs to be as close to the heat as you can get it for an accurate reading.

When I have had temp readings like your pic is showing,
Replacing the thermostat cured it, each time.

[4bye4]

Hi guys I'm not sure that I'm following all this but the water to the gas converter isn't to cool the converter but to heat it up as when the gas changes from liquid to gas (converts) in the converter, it cools and can freeze. Therefore the converter is heated to keep the gas in a vapour.


Sent from my iPad using Tapatalk

[threedogs]

I wouldn't be using any of the gas hoses for engine temp readings

[mudski]

Hi guys I'm not sure that I'm following all this but the water to the gas converter isn't to cool the converter but to heat it up as when the gas changes from liquid to gas (converts) in the converter, it cools and can freeze. Therefore the converter is heated to keep the gas in a vapour.


Sent from my iPad using Tapatalk

Yeah correct but if the op has the sensor on the outlet side of the converter, the water temp there will be cooler that the water going into the converter....

[dom14]

Maybe your thermostat is sticking open.
The aftermarket temp sensor needs to be as close to the heat as you can get it for an accurate reading.

When I have had temp readings like your pic is showing,
Replacing the thermostat cured it, each time.

It wasn't sticking open when I bench tested it. But, I'm suspecting now, it might be opening up too early, as it's pointed out to me in earlier posts.

I'll get a higher temp thermostat and see how it goes.
But, before that, as you advised, I should install the sensor in an appropriate location and get a proper temperature reading first.
I will post the outcome tomorrow.
The sensor wire need to be extended manually. Hopefully, that won't throw the accuracy of the gauge reading too far, but I will find out on a bench test first before I fit it to the coolant system.

Thanx mate.

[dom14]

I wouldn't be using any of the gas hoses for engine temp readings

Yeah, I wouldn't have either. I only opted for that location 'cos of the short sensor wire. My original idea was to stick it near the cylinder head coolant port, where the stock temp sensor is. It will be done that way tomorrow and I will get a far more accurate reading of the coolant temperature.

[dom14]

Yeah correct but if the op has the sensor on the outlet side of the converter, the water temp there will be cooler that the water going into the converter....

Yeah, it's logical to picture it that way.
But, my test above says otherwise. It's even more bizarre, 'cos the coolant line I thought the IN line T joint is producing a slightly less temperature than the OUT line from the LPG converter.
So, it's confusing for me atm.
Obviously, I don't have a good understanding of the coolant circulation system, especially how and where the water pump fits in the diagram and how things are plumped in and out of the water pump, as well as other lines inside the engine block.

It looks like I need to do some homework on that before drawing any diagrams as in the OP.

[kbchez]

Hi Mate, extending the temp wire will make no differance to the reading at your gauge. you said that you moved the sensor to a differant place on the engine. you need to put the sensor in its correct place so it gets the correct coolant reading, then all will be ok.

[mudski]

dom14 Have you got a service manual for the GQ? Haynes etc or the downloadable pdf? I'm sure theres a pic in one of those things showing a diagram of the water flow directions.

[Throbbinhood]

I've got mine installed on the top radiator hose, which is drivers side on my vehicle. Not sure if it's the right spot, but my temps are reliably between 77-82c depending on weather/load/conditions. About right for my thermostat. It's a mechanical gauge for what it's worth. Think it was a $25 speco meter jobby. Tested it in a boiling pot before fitting and read 100c at boiling so is close enough for me.

[jay see]

I find it to have any sensor as close as possible to the original the most practicable and efficient way of getting the correct reading.
Don't know how different your engine is to mine (tb45), but I've got mine just before the thermostat right next to the original one.

Sent from my XT1068 using Tapatalk

[dom14]

I find it to have any sensor as close as possible to the original the most practicable and efficient way of getting the correct reading.
Don't know how different your engine is to mine (tb45), but I've got mine just before the thermostat right next to the original one.

Sent from my XT1068 using Tapatalk

Stock temperature sensor is on the coolant out port on the cylinder head as in below picture.
Today, I extended the aftermarket sensor wire and fitted the sensor right next to the stock one.
Extending the sensor wire didn't upset the temperature reading accuracy that much. About three quarters of
a degree lower than the reading before, so it's ok.
I ran the engine for about ten minutes on idle and temperature didn't go above 63 degrees.
So, it's even worse than the readings I've got before from the T joints of the heater core/LPG converter.
I'm assuming the the thermostat hasn't opened up. So, I'm gonna take the vehicle for a drive tonight and see how it goes.
I'll post the outcome.
If the temperature is still low, then my last temp sensor installation spot is inside the thermostat housing.
If the temperature reading is still low, then I think I would have to say the engine's running bit cold, either due to
thermostat opening up too early or water somehow leaking through the thermostat opening valve/housing.

[dom14]

I've got mine installed on the top radiator hose, which is drivers side on my vehicle. Not sure if it's the right spot, but my temps are reliably between 77-82c depending on weather/load/conditions. About right for my thermostat. It's a mechanical gauge for what it's worth. Think it was a $25 speco meter jobby. Tested it in a boiling pot before fitting and read 100c at boiling so is close enough for me.

So far, I've got 63 degrees from the same spot. I'll take it for a spin tonight and see whether I can hit the temperature at least to be around 75 degrees.

[dom14]

dom14 Have you got a service manual for the GQ? Haynes etc or the downloadable pdf? I'm sure theres a pic in one of those things showing a diagram of the water flow directions.

Thanx mate. I'm having a look right now, both in Haynes and Gregory's.

[dom14]

Hi Mate, extending the temp wire will make no differance to the reading at your gauge. you said that you moved the sensor to a differant place on the engine. you need to put the sensor in its correct place so it gets the correct coolant reading, then all will be ok.

Thanx mate. I read 99 degrees in boiling water after I extended the sensor wire about an extra meter. Previously it was reading 99.7 in boiling water, so that minor difference is no problem at all for my needs. Yeah, I realized now extending the sensor wire won't make a huge difference to the sensor voltage/resistance difference to throw out the reading accuracy too much.

[jay see]

Stock temperature sensor in on the coolant out port on the cylinder head as in below picture.
Today, I extended the aftermarket sensor wire and fitted the sensor right next to the stock one.
Extending the sensor wire didn't upset the temperature reading accuracy that much. About three quarters of
a degree lower than the reading before, so it's ok.
I ran the engine for about ten minutes on idle and temperature didn't go above 63 degrees.
So, it's even worse than the readings I've got before from the T joints of the heater core/LPG converter.
I'm assuming the the thermostat hasn't opened up. So, I'm gonna take the vehicle for a drive tonight and see how it goes.
I'll post the outcome.
If the temperature is still low, then my last temp sensor installation spot is inside the thermostat housing.
If the temperature reading is still low, then I think I would have to say the engine's running bit cold, either due to
thermostat opening up too early or water somehow leaking through the thermostat opening valve/housing.
If you're running for 10 minutes on idle and only getting a maximum of 63 degrees I think the thermostat is stuck open. It only needs to be a little bit. Mine was stuck open by 1-2 mm and that was enough for my temps to stay quite low.

I've never seen a sensor installed in the actual hose like that before don't know if it makes a difference or not to the temperature.

Sent from my XT1068 using Tapatalk

[dom14]

Hi guys I'm not sure that I'm following all this but the water to the gas converter isn't to cool the converter but to heat it up as when the gas changes from liquid to gas (converts) in the converter, it cools and can freeze. Therefore the converter is heated to keep the gas in a vapour.


Sent from my iPad using Tapatalk

When you start the engine the water is pretty cold, so there isn't any heat from water to help the converter but rather the other way around. But, yes even cold water circulating through the LPG converter is better than no water, 'cos the high pressure side of the LPG converter can still absorb some heat from that water, since the LPG(liquid) absorbs whatever the heat it can from the immediate surroundings when it changes to gas state.
Below( as in pictures) happened when I started the engine started burping it.
Obviously the reason for the frost build up on the LPG converter was it wasn't getting any water circulated through it until the air bubbles inside the hoses get burped out. But, it was impressive to notice that, 'cos it didn't happen with this converter before.

[dom14]

If you're running for 10 minutes on idle and only getting a maximum of 63 degrees I think the thermostat is stuck open. It only needs to be a little bit. Mine was stuck open by 1-2 mm and that was enough for my temps to stay quite low.

I've never seen a sensor installed in the actual hose like that before don't know if it makes a difference or not to the temperature.

Sent from my XT1068 using Tapatalk

It's an easier and quicker way to install the sensor. Yeah, I wouldn't wanna leave it like that permanently. I will get a swagelock and fit it properly by tapping a location on the metal, either on the cylinder head coolant port housing or next to thermostat housing. But, I'm pretty sure the reading is accurate. If I dip the sensor in boiling water, it yields an accurate reading, so it should be the same when I inserted it in the coolant hose.

I'm not too sure whether the thermostat stays stuck open. It came out pretty good with the bench tests I did. Only downside was that i was using a crap thermometer, but I manually adjusted the temperature reading(in my head of course) I read from the gauge, as in below pictures. I know , the 71 degrees still bit lower than what's printed on the thermostat(76 degrees), but I thought I should still get a big higher reading than 68 degrees at the heater core inlet joint or the 63 degrees at the cylinder head coolant port.
So, it appears the stock gauge on the dashboard may be not that bad after all(or the stock sensor).
It may be the thermostat after all.

Approx 71 degrees opening temperature may be enough to keep the engine running "cool" at 68 degrees or so as I saw from the spots I installed the aftermarket sensor so far.

After the last test near the thermostat, I will be pulling the thermostat out and I will replace it with the same type thermostat or one that opens up bit higher. I'm also thinking towing the van to see if the temperature hits the desirable point.(say 80+ degrees).

So, I think you are right. My issue must be in the thermostat. I just need one more temperature test near the thermostat before I pull it out.

[GeeYou8]

Davis Craig sensors for thermo fans tucked the sensor into the hose with a rubber wedge in a similar way, they do make a tapping point that you put into the top hose (great for low coolant sensor).
Graham

[dom14]

70 degrees is as high as it showed with the sensor in the cylinder head coolant port.
That's when I was idling the engine at the supermarket for few seconds.
It runs at 66-68 degrees when I drive.
I will get the final reading from the thermostat housing engine block entry port tomorrow.

[Throbbinhood]

Is the sensor getting enough flow where it is mounted? Mine is just one of those adapters, cut a section of the top hose out, put adapter in, screw the gauge into that.

FWIW. My rb30 takes forever to warm up. Just idling, even for ten minutes, only gets the temp up to 65-70. It did it with two thermostats I've had in it. A 5-10minute drive gets it up to temp pretty quick though, don't rely on just idling it to get it to temp.

Yours would take even longer as it's losing temperature to the gas converter as well.

[dom14]

Is the sensor getting enough flow where it is mounted? Mine is just one of those adapters, cut a section of the top hose out, put adapter in, screw the gauge into that.

FWIW. My rb30 takes forever to warm up. Just idling, even for ten minutes, only gets the temp up to 65-70. It did it with two thermostats I've had in it. A 5-10minute drive gets it up to temp pretty quick though, don't rely on just idling it to get it to temp.

Yours would take even longer as it's losing temperature to the gas converter as well.

Thanx mate. I wish you've told me that bit earlier! :D
I think the flow is good. I inserted it a fair bit in with a bit of wire inside the hose as well.
Yeah, to be honest, I'm not too fussed about engine not heating to normal operating temperature after idling for ten-fifteen minutes.
I'm only slightly concerned about it running at that temperature on long trips.
I know, the way it is can be an advantage in big red during the summer time, but not right now though.
I reckon, I can switch the thermostat to fit the season.
As a matter of fact, I'm beginning to believe that what we should be doing with thermostats. Since we seem to be getting somewhat to extreme ends of the temperature spectrum in Melbourne during summer and winter, the thermostat may need to be adjusted accordingly, 'cos I don't think there's such thing as "smart thermostats".

Can you please post a picture of your sensor adapter thingy here?!!
That would help me a lot to get some idea how you plugged in the sensor to the rubber hose.
Thanx.

[threedogs]

Is the sensor getting enough flow where it is mounted? Mine is just one of those adapters, cut a section of the top hose out, put adapter in, screw the gauge into that.

FWIW. My rb30 takes forever to warm up. Just idling, even for ten minutes, only gets the temp up to 65-70. It did it with two thermostats I've had in it. A 5-10minute drive gets it up to temp pretty quick though, don't rely on just idling it to get it to temp.

Yours would take even longer as it's losing temperature to the gas converter as well.

Same here my patrol takes ages to get to temperature Id say a good 10-15 Kays
dom14 you need to bleed the air from that hose on the condenser,

[dom14]

Same here my patrol takes ages to get to temperature Id say a good 10-15 Kays
dom14 you need to bleed the air from that hose on the condenser,

What condenser mate? Did you mean the radiator??!!

BTW, the reason you're still seeing T-joints at the back of the coolant intersection to the heater core/LPG converter is that, I did get Y joints, but they are taking up a fair bit of room and looks pretty cumbersome. So, I was thinking re-doing it in a series like setup or something without having to use T or Y joints. The thought has crossed my mind while ago, hence the reason for not putting Y joints there. Now, the member @garett (http://www.nissanpatrol.com.au/forums/member.php?32502-garett) kinda indicated that's how he would do it as well.

So, I'm thinking getting a couple of joiner pieces and a piece of hose and converting it from parallel setup to series setup, as depicted in below diagrams.

Any thoughts, ideas?!!!
ATM, I can't see any advantage of this existing parallel setup other than being a PITA with extra T-joints and extra headaches that come with it.
Please correct me me, if I'm about to do the wrong thing.

[Throbbinhood]

Can you please post a picture of your sensor adapter thingy here?!!


Hey mate, don't have a pic of it installed, but this is basically what I bought. Should give you an idea.

http://www.ebay.com.au/itm/like/161306026253?lpid=107&chn=ps

[jay see]

Hey mate, don't have a pic of it installed, but this is basically what I bought. Should give you an idea.

http://www.ebay.com.au/itm/like/161306026253?lpid=107&chn=ps dom 14

If you want one of these I've got a brand new aeroflow one that you can have.

http://www.nissanpatrol.com.au/forums/images/imported/2016/08/228.jpg

Sent from my XT1068 using Tapatalk

[dom14]

I installed the temperature sensor in the coolant port right next to the thermostat housing.

I went for an uphill drive in Mount Dandenong and the temperature went up to 71 degrees and that was it.

[Throbbinhood]

Where does that coolant line go?

Why not leave it in the top hose and work from there. That way at least you've got some Continuity in your testing.

[dom14]

Where does that coolant line go?

Why not leave it in the top hose and work from there. That way at least you've got some Continuity in your testing.

The hose I attached the sensor in above picture goes to the heater core/LPG converter. The coolant line the hose joins comes directly out of the engine block water jacket behind the thermostat(not after it). The thermostat hose in the picture carries "cold" water from the bottom hose of the radiator. So, it's lot "colder" than the coolant outside the thermostat until the thermostat opens.

[dom14]

Now I'm pretty sure now it's the thermostat that causes the coolant temperature to run bit low in mine.
I'll be replacing the thermostat with higher temperature setting one.
But, the existing one is also opening up few degrees lower than it should be.


I haven't heard anything from anybody so far about my idea or re-routing the coolant lines to the heater core/LPG converter, from parallel setup to a series setup as in above diagrams and as I pasted it below again.

So, where is everybody? No opinions, ideas, thoughts, advice on that at all????!!!!!

BTW,
The original heater core/LPG converter coolant re-routing diagram of mine was slightly misleading 'cos I made it painted like I'm taking the coolant outlet line directly from thermostat housing coolant line, which it is NOT.
Corrected diagram is as below.

[GeeYou8]

The hose I attached the sensor in above picture goes to the heater core/LPG converter. The coolant line the hose joins comes directly out of the engine block water jacket behind the thermostat(not after it). The thermostat hose in the picture carries "cold" water from the bottom hose of the radiator. So, it's lot "colder" than the coolant outside the thermostat until the thermostat opens.

I thought that the thermostat controlled the hot water leaving the engine into the top of the radiator to be cooled then pumped from the bottom of the radiator through the block (pump assisted thermo syphon).

[dom14]

I thought that the thermostat controlled the hot water leaving the engine into the top of the radiator to be cooled then pumped from the bottom of the radiator through the block (pump assisted thermo syphon).

Yes, that's right. That's why I had to install the sensor behind the thermostat in the block. The way to do that is to use the pipe that comes out of behind the thermostat that leads the hose to the heater core/LPG converter. That's what I've done in above picture in post number 36. Until thermostat opens, there is no flow. So, the water in the engine block+cylinder head stays there without flowing into the radiator and circulating. Obviously if the radiator is not full, some water will flow into the radiator via the water pump action, but that would be minimal and can even help engine warm up bit quicker. This is how the "burping" works as well. As we pour water into the radiator it goes into the cylinder head, then into the engine block while air bubbles coming out of the radiator with the help of water pump speeding it up. Some air bubbles may get trapped at the coolant lines between thermostat and radiator. That's why it's important to "burp" the coolant system until the engine is warmed up enough to open up the thermostat, so the whole circulation cycle completes while pushing out any air bubbles.

[Robo]

1) replace the thermostat for a new Standard one.
also you may be surprised to find genuine should be a competitive price.
Don't use a hi flow thermostat unless you have a mods to suit, I tried that approach and it actually ran to hot.

Personally don't like the idea of just routing the coolant to converter then heater core then finally back to block.
Winter you will probably notice cab not as comfy as it should be.
Coolant re-entering the block will be to cold all year round.
If it was best practice to do it that way it would be done that way instead of using a tee pce.
There will be a whole host of reasons why the T is used and not plumbed without it.

Just replace the thermostat you'll find it's fixed and gauge will read in the middle again.
cheers

[dom14]

1) replace the thermostat for a new Standard one.
also you may be surprised to find genuine should be a competitive price.
Don't use a hi flow thermostat unless you have a mods to suit, I tried that approach and it actually ran to hot.

Personally don't like the idea of just routing the coolant to converter then heater core then finally back to block.
Winter you will probably notice cab not as comfy as it should be.
Coolant re-entering the block will be to cold all year round.
If it was best practice to do it that way it would be done that way instead of using a tee pce.
There will be a whole host of reasons why the T is used and not plumbed without it.

Just replace the thermostat you'll find it's fixed and gauge will read in the middle again.
cheers

Thanx mate. I was considering it following another member's comment. I'm sure there's a reason for T(or preferably Y) pieces were used. I was open to the idea of re-routing it 'cos some of the LPG conversion work(electrical wiring work) on this vehicle was well below
standards. So, I was contemplating on the possibility of sloppiness by the installer with the coolant plumbing as well.
It's obviously too easy to plumb the coolant hoses to the LPG converter & heater core without T joints. So, there must be a reason for the extra work of using T pieces.
I've been trying to find some relevant information online on coolant plumbing specs on LPG, but haven't been able to so far.

BTW, I don't have to route the coolant first into the LPG converter. It can be into the heater core first and then into the LPG converter as well. By following the way the coolant valve work on the heater core


, I'm pretty sure now that shutting the coolant valve by sliding the dashboard heater controller to cool direction doesn't mean shutting the water flow then and there on the heater core.


It must be flowing back into the block(or LPG converter, depending on the plumbing priority)regardless of whether the hot coolant goes through the heater core or not. Having a valve that shuts the coolant flow in the heater core can't be a good thing. I think the way HVAC(particularly heater control valve) works in the RB30 Patrol is as in below diagram.

http://i128.photobucket.com/albums/p174/Buggin_74/Subaru%20conversion/Commodore_heatertap.jpg

Thanx

P.S. I said "I'm pretty sure" in the writing in red above. But, actually I'm now fairly certain I was wrong about it. So, the statement in RED is INCORRECT.
The reasons are explained in the next post and more details are in the following posts.

[dom14]

It appears the heater core coolant flow control valve is apparently a single cable operated valve on the coolant entry pipe on the heater core, as depicted in below picture from Gregory's manual.

It also explains the reasons for using parallel coolant routing setup with two T joints for the heater core & LPG converter. A series setup would've created a coolant flow blockage for heater core, LPG converter or both of them when the coolant entry valve to the heater core is shut.

[Throbbinhood]

Well, if it's pumping it FROM the bottom of the radiator, to the thermostat, your reading is always gonna be low isn't it? Won't your reading be cold, with the colder water coming from the radiator that's being cooled as you drive?

If it's on the top hose, you'll get the hotter reading no? The water would be coming out of the engine, and into the radiator no? I've noticed since changing the thermostat in mine, it sat a little higher temperature wise (80-82), used to sit on 78-80, both 77c thermostats, though I was towing a camper and had a kayak on the roof..

I guess, as a final question, if the coolant flow is coming out of the engine to the top hose of the radiator, then down to the bottom, through the thermostat and back into the engine, wouldn't the thermostat be closing because of the cooler water coming from the radiator? Or do I have this all backwards?

[dom14]

Well, if it's pumping it FROM the bottom of the radiator, to the thermostat, your reading is always gonna be low isn't it?

Not always. The reading will be the highest you get until the thermostat opens. When thermostat opens, you notice a 'sudden' drop in temperature for few seconds. then it will rise again.


Won't your reading be cold, with the colder water coming from the radiator that's being cooled as you drive?

Yes, that is a valid argument. That's why the temperature sensor is inside the ancillary hose next to the thermostat housing, which comes directly out of the engine block behind the thermostat.
So far, I've got the highest reading from the current location, which is behind the thermostat in the engine block.
I believe the test speaks for itself.


If it's on the top hose, you'll get the hotter reading no?

Yes and No. Yes, because the hot water from the block rises to the head via thermosiphoning & pump assistance.
But, the heat obviously spread around the aluminium head quickly. So, NO because of "thermal efficiency" of the the aluminium head. That's why I believe the temperature reading I got from the coolant port on the cylinder head(from the radiator top hose) wasn't any better than the reading I've got from the port behind the thermostat on the engine block.


The water would be coming out of the engine, and into the radiator no?

Yes, just as I painted in my rough sketch.


I've noticed since changing the thermostat in mine, it sat a little higher temperature wise (80-82), used to sit on 78-80, both 77c thermostats, though I was towing a camper and had a kayak on the roof..

You did it right.

I'm simply more interested in getting the temperature reading from more than one place to device a good failsafe idiotproof warning system(for the idiot, which is me, 'cos I'm pretty good at "falling asleep" on the wheel or daydreaming while the engine's getting cooked from overheating. it's genetics, don't blame me. ;) :D)


I guess, as a final question, if the coolant flow is coming out of the engine to the top hose of the radiator, then down to the bottom, through the thermostat and back into the engine, wouldn't the thermostat be closing because of the cooler water coming from the radiator? Or do I have this all backwards?

No, it's a pretty damn valid intelligent question. The 'cold' water that enters from the bottom of the radiator into the thermostat housing aren't that "cold" after all. Then there's enough heat behind the thermostat 'cos the pump circulates water inside the engine block(and head) from front to back. That would be enough heat to keep the thermostat opened once it's opened.
And yes, if the outside the temperature is sub zero, thermostat can shut from the "cold" water entering from the radiator, and that's way it should be, so the correct temperature inside the engine block & cylinder head can be maintained. But, that's not likely to happen in Melbourne(don't take my word on it though, I ain't gota degree in engineering thermodynamics yet ;) ).
Overall, it's a reasonably efficient cooling system design, 'cos lot of thermodynamic experiments precedes these cooling system designs.

Imagine if they design it the other way around. Coolant enters the engine from cylinder head coolant port and travels down to the engine block towards the thermostat on the engine block. That won't do a lot of good in this particular engine design, I think, 'cos this aluminium alloy cylinder head is NOT that good with handling temperature fluctuations and can crack over time from thermo metal fatigue.(my wording). So, that's why I think Nissan engineers designed the direction of coolant flow the way it is.
Having said that, there are engine designs out there where the thermostat is on the cylinder head and the direction of coolant flow even may be the other way around. It all boils down to the way the engineers design the coolant system accommodate the thermal efficiency of whole engine.

Another thing is that even though these coolant system designs are good for what we pay for the vehicle, we can improve it a lot by installing aftermarket systems like "Davies Craig Temperature Control Systems" using electric water pumps and clever electronics. These things are in the market, I think, 'cos good engine performance and longevity comes down to heat management at the end of the day(This is why I might have come out as a bit pedantic with this temperature measuring thing). Browse through below links for more info.

https://daviescraig.com.au/switches-controllers

https://www.sparesbox.com.au/davies-craig-electric-water-pump-lcd-controller-kit-8000?gclid=Cj0KEQjwouW9BRCN0ozIifTI6_cBEiQAD9gNsVb JxHohOJRn7NuF1Huhdc89RghdkQzf-X36DTNIStcaAlsn8P8HAQ&gclsrc=aw.ds

https://daviescraig.com.au/media/921/1431648020.8000-DigitalController14.01.15.pdf


One last thing I thought I should mention here is that the thing we do by pumping cold water into a leaking and overheated cooling system is many times the very thing that can cause the cracking of the aluminium alloy cylinder head or even the cast iron engine block. I've seen that happened more than one time(yes, I have seen a cracked cast iron block from pouring cold water into it). As a matter of fact, I believe that's how I managed to crack few places of my cylinder head back in 2011, when it overheated due to a burst coolant hose leaking the coolant. I grabbed the cold water from the back of the car and poured it straight into the badly overheated cylinder head through the radiator. That must have caused further damage by suddenly cooling down the badly overheated cylinder head. The best thing we can do to an overheated engine is to stop it and let it cool down by itself. NOT pouring cold water into it to cool it down.

P.S.
Your question still makes sense. I just discovered the coolant flow direction that I sketched in the diagram earlier was NOT correct between the heater core and engine block. The ancillary coolant port next to the thermostat on the engine block actually receives water from the heater core(not sending water out of it). I've corrected the final diagram as below.
I will also move the sensor from front ancillary hose port to the back ancillary hose port of the engine block, and see whether it can yield a slightly higher temperature reading. Logic says it should, as the current spot at the return line of the heater core should be slightly cooler. I will update the outcome soon.

[dom14]

It's quite possible to remove the water pump & thermo fan and then install a Davies Craig system with electric pump+electric thermo fans. Helps with removing the drag from the mechanical water pump & mechanical thermo fan. Not to mention it will maintain the engine coolant temperature in the optimum level.

[Robo]

Thanx mate. I was considering it following another member's comment. I'm sure there's a reason for T(or preferably Y) pieces were used. I was open to the idea of re-routing it 'cos some of the LPG conversion work(electrical wiring work) on this vehicle was well below
standards. So, I was contemplating on the possibility of sloppiness by the installer with the coolant plumbing as well.
It's obviously too easy to plumb the coolant hoses to the LPG converter & heater core without T joints. So, there must be a reason for the extra work of using T pieces.
I've been trying to find some relevant information online on coolant plumbing specs on LPG, but haven't been able to so far.

BTW, I don't have to route the coolant first into the LPG converter. It can be into the heater core first and then into the LPG converter as well. By following the way the coolant valve work on the heater core, I'm pretty sure now that shutting the coolant valve by sliding the dashboard heater controller to cool direction doesn't mean shutting the water flow then and there on the heater core.
It must be flowing back into the block(or LPG converter, depending on the plumbing priority)regardless of whether the hot coolant goes through the heater core or not. Having a valve that shuts the coolant flow in the heater core can't be a good thing. I think the way HVAC(particularly heater control valve) works in the RB30 Patrol is as in below diagram.

http://i128.photobucket.com/albums/p174/Buggin_74/Subaru%20conversion/Commodore_heatertap.jpg

Thanx

P.S. I said "I'm pretty sure" in the writing in red above. But, actually I'm not sure yet.

Just use the T pcs mate, reversing the flow direction to heater core firstly will reduce the optimal level of heat needed for the conversion of lpg to vapor, the reverse of previous statement, less heat for cabin for the cooler months.

see how you go with the thermostat and let us know how you go, cheers.

[dom14]

Just use the T pcs mate, reversing the flow direction to heater core firstly will reduce the optimal level of heat needed for the conversion of lpg to vapor, the reverse of previous statement, less heat for cabin for the cooler months.

see how you go with the thermostat and let us know how you go, cheers.

Yeah mate. You were right about T pieces being there for a reason. And I was wrong about heater core coolant entry having a four way valve as above anyway. I've corrected that in a post after that, and I'm just about to post all the details, pictures from the factory manual and Gregory's manual about it.
T joints were put there 'cos there's no other way to do it. Series setup would've cut the coolant flow to LPG converter or heater core or both depending on which one I plumb the coolant entry first. When the tap inside the heater core is shut by sliding the dashboard heater slider to cold, that will cut the coolant flow completely, which won't be a good thing for the LPG converter to start with.(and may even create cavitation air bubbles on the coolant return line to the engine block, which would "help" to create cracks in the cylinder head in no time, so it's definitely a bad idea)

I will replace the thermostat with a brand new stock one (76 degrees) to start with and see how it goes, 'cos the current one is opening up at around 70 degrees or bit less, which I think the major reason for low temperature. If the new one still yields low temperature then I will install a one bit higher, like 80 degrees or so.

I will also replace T pieces with Y pieces soon. I've been told it's better for the flow and helps reduce cavitation(air bubbles inside coolant).

Cheers
Dom

[dom14]

Factory manual excerpts & Gregory's manual excerpts below indicate there a "water control cock rod" and the "temperature control air direction flap valve", in which appears both are controlled by the cable attached to the temperature control slider on the dashboard.

[Robo]

Yeah mate. You were right about T pieces being there for a reason. And I was wrong about heater core coolant entry having a four way valve as above anyway. I've corrected that in a post after that, and I'm just about to post all the details, pictures from the factory manual and Gregory's manual about it.
T joints were put there 'cos there's no other way to do it. Series setup would've cut the coolant flow to LPG converter or heater core or both depending on which one I plumb the coolant entry first. When the tap inside the heater core is shut by sliding the dashboard heater slider to cold, that will cut the coolant flow completely, which won't be a good thing for the LPG converter to start with.(and may even create cavitation air bubbles on the coolant return line to the engine block, which would "help" to create cracks in the cylinder head in no time, so it's definitely a bad idea)

I will replace the thermostat with a brand new stock one (76 degrees) to start with and see how it goes, 'cos the current one is opening up at around 70 degrees or bit less, which I think the major reason for low temperature. If the new one still yields low temperature then I will install a one bit higher, like 80 degrees or so.

I will also replace T pieces with Y pieces soon. I've been told it's better for the flow and helps reduce cavitation(air bubbles inside coolant).

Cheers
Dom

Forget about installing a thermostat with a temp you think may be the right temp setting.
Ask Mr Nissan for a thermostat to suit your vehicle VIN number.
Then ask him what'c the temp setting that's stamped on it?.
Don't quote me, I believe the Gen p/No is 2120042L01W and about $45.

Cavitation from a t piece--- doubt it.
The Y would reduce back pressure for sure, just insure you get the flow direction correct.
that is the stem feeds the y on the hot side too heater and lpg mixer
and the y part feeds back from the heater and lpg mixer to the stem on return .
I tried Y's on GQtb42 lpg, didn't see any difference at the gauge , you may get a deg or two difference if you spend $20 per joint on a Y.
Then again it may allow the water to flow to fast through the lpg and heater cores to allow sufficient time for more heat transfer who knows!.
The speed of flow needs to be just right to allow time to cool off, to fast and water retains more heat.
Again this gets back to the job of the thermostat helping to control flow.
See how you go with the thermostat first hay. cheers.

[dom14]

Forget about installing a thermostat with a temp you think may be the right temp setting.
Ask Mr Nissan for a thermostat to suit your vehicle VIN number.
Then ask him what'c the temp setting that's stamped on it?.
Don't quote me, I believe the Gen p/No is 2120042L01W and about $45.

Cavitation from a t piece--- doubt it.
The Y would reduce back pressure for sure, just insure you get the flow direction correct.
that is the stem feeds the y on the hot side too heater and lpg mixer
and the y part feeds back from the heater and lpg mixer to the stem on return .
I tried Y's on GQtb42 lpg, didn't see any difference at the gauge , you may get a deg or two difference if you spend $20 per joint on a Y.
Then again it may allow the water to flow to fast through the lpg and heater cores to allow sufficient time for more heat transfer who knows!.
The speed of flow needs to be just right to allow time to cool off, to fast and water retains more heat.
Again this gets back to the job of the thermostat helping to control flow.
See how you go with the thermostat first hay. cheers.

Cool, thanx mate.
Yeah, I'm not too fussy about Y pieces, but I bought them while ago and it's somewhere in the stash of crap. :)
The reason I didn't install them 'cos Y's are bit cumbersome, comparing to T's.
They are obviously bit better for the flow. Cavitation thing is a suggestion by a forum member. So, I went by that advice.

I think my rig's been running low temp for a quite a while without me noticing it.
I'm guessing the excess blow by is probably from that, causing bit of extra wear on piston rings or so.

Thanx for emphasizing the importance of the flow speed above mate. I now know the engine cooling system is far more complicated than I would like to believe. I still understand very little of it, but at least I'm aware of my ignorance now, so I won't muck around with it without doing the due homework. :). It's good to know that i don't know. :D. We usually end up in trouble when we don't know that we don't know. :cheers:

Cheers
Dom

[Robo]

I'm no expert by any means, picked up on a few bits over the yrs and trying to help out if I can, do unto others.
Hate to see someone having trouble, we've all been there hay.
And yes the Y's take up a bit more room than the tee's for sure.

[dom14]

I just discovered the coolant flow direction that I sketched in the diagram earlier was NOT correct between the heater core and engine block. The ancillary coolant port next to the thermostat on the engine block actually receives water from the heater core(not sending water out of it). I've corrected the final diagram as below.
I will also move the sensor from front ancillary hose port to the back ancillary hose port of the engine block, and see whether it can yield a slightly higher temperature reading. Logic says it should, as the current spot at the return line of the heater core should be slightly cooler. I will update the outcome soon.

These are the final and accurate diagram(s) of RB30 Patrol coolant flow. The second one is taken out of R31 Skyline(RB30 engine) coolant flow diagram and slightly modified to suit RB30 Patrol(carby) engine. Previous diagrams in the previous posts of this thread were already corrected to reflect below diagrams.

[Throbbinhood]

Forever impressed by your work dom14. Your diagrams make life much easier to visualize things.

Also, tried messaging you back, but your inbox is full :)

[dom14]

Forever impressed by your work dom14. Your diagrams make life much easier to visualize things.

Also, tried messaging you back, but your inbox is full :)

Yeah, mate. Just been busy "upto my arse". Need to do bit of housekeeping with my email box. Cheers.

P.S. It's not easy, 'cos most of the email, if not all, are really important communication with members. :), I just have to forward them to another email box or something. :)

[dom14]

Coolant system Myths

I picked below said coolant myths from an article on the web.

Coolant can be pumped too fast through the engine for it to absorb enough heat, or
Coolant can be pumped too fast through the radiator for it to cool properly, or
Cooling can be improved by slowing the flow of coolant through the radiator so it cools more completely.

The detailed article that explains why the above are myth is below.
http://www.pirate4x4.com/tech/billavista/Cooling/


Relevant part from the long article above, that relate to the myths above, is below.


Myths

For those that cling tenaciously to myths, I am going to take one last crack at forever dispelling the Granddaddy of them all when it comes to cooling systems.

The myth is stated as either:

Coolant can be pumped too fast through the engine for it to absorb enough heat, or
Coolant can be pumped too fast through the radiator for it to cool properly, or
Cooling can be improved by slowing the flow of coolant through the radiator so it cools more completely.
NONE of these is true. The simple truth is that higher coolant flow will ALWAYS result in higher heat transfer and improved cooling system performance.

The reason the myth is so persistent, is that: a) without knowledge of fluid dynamics and laws of thermal conduction it does make a kind of intuitive sense and b) it is based on a tiny kernel of truth, but that kernel of truth does not explain the overall system behaviour and so, interpreted out of context, leads to a completely erroneous conclusion.

So, let's start with the tiny nugget of truth. If you had a sealed rad (no flow) full of hot coolant, and subjected that rad to airflow, yes, the longer you left the coolant in the rad, the more it would cool. However, if you were to plot that cooling over time, you would find that the RATE at which the cooling takes place is an exponential curve that decreases with the temperature difference between the hot coolant and the air. Put another way - when the temperature difference (delta-T) between the hot coolant and the airflow is large, heat transfer (cooling) initially takes place very, very quickly (almost instantaneously). But as that happens, and the coolant cools, the delta-T becomes less, and the RATE at which further cooling happens gets less and less until the point where the coolant and air are almost the same temperature and continued cooling takes a very long time. This is Newton's law of cooling. To illustrate this, recall my "quenching steel in a bucket" analogy.

A good example of this law can be seen when quenching a red-hot piece of steel in a bucket of water. At first, the temperature difference (delta-T) between the red-hot steel and the water is huge - therefore the initial heat transfer occurs at a great rate - the steel initially cools very fast - almost instantaneously. However, after this initial cooling, the delta-T is much smaller, so the remaining cooling occurs much more slowly. If you removed the steel after a second or two - it has cooled a lot - but it will still be warm. To continue cooling the steel to the temp. of the water, you have to leave it in there quite a bit longer - because as it cools - the rate of cooling continually decreases as well. In short - initial cooling is fast, but subsequent cooling occurs more and more slowly until cooling that last little bit takes a long time.

So what does this mean? Basically it means, the longer the coolant stays in the rad, the less efficient the cooling that takes place is - to the point that the rate of cooling is so slow as to be detrimental to overall system cooling. Better to dump the big load of heat right away and go back quickly for another load than hang about waiting for a last little bit of insignificant cooling to happen.

To understand fully, we have to put our rad back into the whole system where coolant is flowing and consider the effects of flow rate on the system as a whole.

Slowing the coolant in the rad may allow that coolant (the coolant in the rad) to dissipate a little more heat (but not much), and at an ever decreasing rate (exponentially decreasing) BUT since the cooling system is a closed-loop system, you also have to consider what’s happening outside the radiator if you slow the flow - especially to the coolant in the engine. If you slow the coolant through the rad, you slow the coolant through the engine too. And this coolant is subject to the same laws - the greater the initial temperature difference between the engine and the coolant, the greater the rate at which the coolant absorbs the heat from the engine. BUT - if we leave the coolant in contact with the engine for longer by slowing the flow through the rad, the delta-T between engine and coolant decreases and with it the rate at which the coolant in the engine absorbs the heat from the engine. Meanwhile the engine is banging away producing heat, but the coolant is absorbing it at a slower and slower rate - that heat has to go somewhere, and since the slow coolant is becoming less efficient at absorbing it - it stays in the metal - and the metal overheats!

Meanwhile, back at the rad, you're wasting time trying to shed the last little bit of heat when the delta is small instead of carrying away the “big chunks” of heat. And the situation just gets worse and worse in a downward spiral.

Imagine emptying a truckload of sand using a small wide-mouth container vs. a larger narrow-mouth container. The job will get done quicker by making more trips with the smaller container that takes less time to fill and empty, rather than taking the time to fill the larger narrow-mouth container and then taking the time to empty it – that extra in the larger narrow-mouth container isn’t worth it – better to dump the load and go back for more.

Or, how about this for those who are fans of elaborate metaphors
Imagine a circular train track with two stations opposite each other and rail cars that fill the whole track. One station has an endless supply of passengers trying to get on and the other is where they get off and disperse. Your job as the train driver is to move as many people as possible to keep them from accumulating at the embarkation station and crushing each other. Now imagine the passenger cars are funnel-shaped on the inside. This means the first big batch of people can get on and off quickly, but completely filling the car takes a lot longer as people have to squeeze into the narrower portion.
So, you could drive the train slowly, only moving along after each car has completely filled and completely emptied… but efficiency will be greatly reduced as it takes so long to get those last few people on or off the car – meanwhile the never ending supply of people at the embarkation station never stops and the system backs up and the people get crushed because, even though more people get on or off each car, the whole system is less efficient.


OR

You could drive the train fast, quickly loading and unloading the big, easy-to-fill, portion of each car, forget about the smaller portion, and keep picking up and dumping off a large group of passengers as fast as you can. In fact – the faster you go, the better…the more efficient at moving large numbers of people the system will be. Screw the last stragglers – they’re insignificant and won’t help you – just move the big chunk and move on, going back for more, more often.

So – you want high flow / high (turbulent) speed so it picks up and dumps off the most heat quickly – it’s inefficient to try and shed the last little bit of heat when the delta is small, and can lead to overheating because you’re wasting time not carrying away the “big chunks” of heat.

[Robo]

m2cw.
Real world , were ambient air temp varies, vehicle speed , air flow speed through rad varies, then also factor in- head wind, up hill etc.
We still need the system to operate as it was designed to, or have extra capacity to compensate for any increases in thermal load placed upon it from load & or worked engine etc.
Some may think a std rad is up to the task, that's only due to some extra capacity factored in for hot weather (real world) & to prevent warranty claims, no-one buys cars new that overheat easily.
And a given, the thermostat needs to be working correctly.

So how are the temps going in your's now?.

[dom14]

I haven't had a chance to test it yet, but I moved the temperature sensor into the coolant port on the rear of the block.

I'm dealing with ways to cut down blowby atm.
I'm making a catch can setup( a home made cheap one) to start with and monitor oil mist output.
Actually, I'm thinking two catch cans for each breather out of the rocker cover and plumb then into the PCV input & air cleaner, the way it's connected in the factory setting.
I'll open a different thread on that as well.
If it works, then I can consider buying a proper aftermarket catch can.

I'll post the outcome of the thermostat & temperature reading soon.
The engine's definitely running tad cooler, and the thermostat is definitely the biggest contributor to the 'problem'.
I guess running closer to 70 degrees may not be that bad during warmer months as it may run bit hotter as it's coming to Spring and Summer now. I'm more worried about engine's not reaching it's temperature quickly enough.
The most of the condensation buildup under the rocker cover(near the oil filler cap) is I think from engine oil NOT getting hot enough to vaporize the moisture.
I think, if I can get the engine to reach the operating temperature quickly enough and maintain the temperature around 80 degrees celisus or so, then I would be happy.

Yeah, it makes sense to me that there is such thing as "coolant can flow too fast" through the coolant system, 'cos if not temperature, the pressure will be affected(which may be a bad or good thing, depend on each situation). :)
One thing is obvious though. Coolant system is far more complicated than it looks, and lot of "hard physics" go into making them.

It's definitely a pretty complicated subject.(namely the "heat management").

I mentioned in a lengthy post above that "pouring cold water into an overheated engine" is a bad idea and the best we can is to stop the engine and let it cool down normally, 'cos pouring cold water, especially too much cold water can cause the overheated head and block to crack by sudden drop of temperature. I also heard literature against that, saying the temperature of the head and block even rises more as soon as we stop the engine(because whatever the left of the coolant stops flowing).

But, I think that temperature rise does minimal damage 'cos

1)It will be for a very short period
2)It's a far cry from stopping the engine and then pouring lot of cold water into the engine which has a lot higher probability of damaging the engine.

I think, one thing we can do is to open the radiator cap(if it can be opened safely), and pour water a little bit at a time and run the engine to keep the coolant flowing. But, that can be way too dangerous.
Opening an overheated radiator cap with hot steam in it ain't a good idea, regardless of any safety precautions that we can take.

Best thing we can do is to stop the overheated engine and let it cool down by itself, IMO.

[Throbbinhood]

Just out of curiosity, your viscous hub isn't locked on or anything like that is it?

Also, does your thermostat have a little bypass nipple on it? I know this is a weird question, and my rb30 has the nipple on it and runs 78-82. But when chasing an issue with my xr6turbo where it simply wouldn't heat up quickly, and would cool down on long freeway stretches (to the point the heater was cold). Turned out to that it had one of those nipple holes in it for some reason. Put one without the nipple thing and it's been perfect since.

[UncleFrosty]

Thanks for your masterclass Dom (elaborate metaphors n all)!
Wish I'd had such practical explanations a coupla decades ago. Might've saved me failing Thermo a few times...
Eastop and McConkey is still on my shelf somewhere... stopping the dust from resting on that bit of shelf.
Cheers

[dom14]

Just out of curiosity, your viscous hub isn't locked on or anything like that is it?

Also, does your thermostat have a little bypass nipple on it? I know this is a weird question, and my rb30 has the nipple on it and runs 78-82. But when chasing an issue with my xr6turbo where it simply wouldn't heat up quickly, and would cool down on long freeway stretches (to the point the heater was cold). Turned out to that it had one of those nipple holes in it for some reason. Put one without the nipple thing and it's been perfect since.

Yeah, all the thermostats come with that little nipple thing or similar device afaik. It's basically a bypass valve to allow any expanding steam, water, ice etc to escape from the engine block into the low pressure side of the coolant system.

The ones that doesn't come with the nipple thing on the thermostat comes with a different setup that works with the engine block thermostat hole cavity, I think.
I'm guessing in your xr6turbo, the problem would've caused by the "nipple" valve being stuck open or something, which would constantly leak the water into the low pressure side of the coolant system(coolant entry hose from the radiator to thermostat/engine block). That would mess with engine temperature control and constantly remove the engine heat from the engine and prevent the engine from reaching the operating temperature. As far as installing a thermostat without the bypass valve? I'm not if that's a good idea though. Freezing of coolant is not likely to happen in Melbourne, but I reckon it's still handy with letting any steam bubbles to get out of the engine block, in case they develop by overheating(thermostat stuck closed) or bit too "feisty" water pump action, etc. I reckon the bypass nipple valve is a good "fail safe" redundancy device. If the engine block coolant system is designed to have a thermostat with a bypass "nipple" valve. then it's a good idea to replace with a one just like the factory one.

Make sure the thermostat you replaced on your RB30 has that bypass nipple on it. It can save the engine in a not so common situation(like a situation where a faulty thermostat stays stuck closed).

[dom14]

Just updating guys,
I put the temperature sensor in the rear coolant port on the engine block.(as in the diagram below).
Temperature goes upto 73 degrees celcius of so(the highest so far).
And this was from driving on the highway, freeway and uphill for few hours.
So, the thermostat is definitely not upto scratch(which I already know from all the "fiddling" so far).
Obviously I haven't replaced the thermostat yet. I wanted to finish all the temperature "sensor spot testing",before I replace it
with a brand new.
Next job is to replace the thermostat and also install the the second aftermarket temperature gauge/sensor.
I haven't figured out where to install it yet. I'm thinking cylinder head or engine block(not in the coolant system).

[dom14]

Thanks for your masterclass Dom (elaborate metaphors n all)!
Wish I'd had such practical explanations a coupla decades ago. Might've saved me failing Thermo a few times...
Eastop and McConkey is still on my shelf somewhere... stopping the dust from resting on that bit of shelf.
Cheers

Hey RossKal,
I just found out what you meant by "Eastop and McConkey".
If you've been through Engineering Thermodynamics books like that, then you understand the cooling system quirks far far better
than I would ever do. :)
I've never got into Engineering Thermo, but if you wanna debate, Quantum mechanics and relativity, I'm your man. :D

BTW, here is a link to download the "Eastop and McConkey", in case you've already stepped into the 'space age' & read books as ebooks on tablets, as I do these days. ;)
I won't get into Engineering thermo like you did though. The subject gives me headaches and constipation, as you've seen from my long posts in this thread. :clapping: ;)

https://onedrive.live.com/?cid=4816EE26585699D9&id=4816EE26585699D9%21331&parId=4816EE26585699D9%21111&o=OneUp

or here

http://www.mediafire.com/download/tpr4t7a3u443iqh/Applied+Thermodynamics+and+engineering+Fifth+Editi on+By+T.D+Eastop+and+A.+McConkey.pdf

[dom14]

Just out of curiosity, your viscous hub isn't locked on or anything like that is it?


Nah. I checked it while ago. Viscous fan moves freely, though I can't say for sure whether the viscosity/resistance of the silicon liquid inside it is in the same condition as it was years ago or not.

I've been thinking...it would've been great if the viscous fan has as some kinda better thermo liquid & switch that prevents it from spinning the fan until the thermostat opens up?!!
I guess there's no such thing. Even if there IS, it's lot simpler to use electric thermo fan system.
Without a fully contained fan shroud, it would've been not too safe to have a fan that comes on like that anyway, even if the fan starts turning gradually.

I'm thinking, down the track some day, to come up with an electric fan cooling system, including an electric water pump, just like Davies Craig system, except I will be building it myself from scratch, except the electric water pump, which I would have to buy. The rest of the electronics and fan system is not to hard to build from scratch.

http://daviescraig.com.au/electric-water-pumps

I like to think these efficient coolant systems can add quite a few years of good life to the engine's lifespan.

https://www.youtube.com/watch?v=ew9Dn9NnwSo

[UncleFrosty]

Hi Dom
Thx for the link. I'm still old school paper version, though interestingly it's still 5th Ed 20yrs later! I pretty much hated Thermo at the time, but it was one of the units required to pass... P's make degrees (in my case anyway...)
No fear of QM debate bud - my scant knowledge only covers what the LHC is an acronym for! As far as quarks/neutrinos etc - no idea at all, but it is interesting stuff.
Now onto the really interesting stuff...
A simple paddle-type flow switch on top side of thermostat, with a relay to an air-con type clutch attached to fan (somehow replacing viscous coupling) or relay to elec fan, should cover your needs?
More stuff to go wrong IMO, but could delay fan enough to stop things cooling down too quickly?

[GeeYou8]

I was thinking of running a PWM controller for radiator fans on speedway car, a bit more elegant than the bang on bang off of a relay.
Would need a bit of tuning to get gain, derivative & integral mixing right.
Graham

[dom14]

Hi Dom
Thx for the link. I'm still old school paper version, though interestingly it's still 5th Ed 20yrs later! I pretty much hated Thermo at the time, but it was one of the units required to pass... P's make degrees (in my case anyway...)
No fear of QM debate bud - my scant knowledge only covers what the LHC is an acronym for! As far as quarks/neutrinos etc - no idea at all, but it is interesting stuff.
Now onto the really interesting stuff...
A simple paddle-type flow switch on top side of thermostat, with a relay to an air-con type clutch attached to fan (somehow replacing viscous coupling) or relay to elec fan, should cover your needs?
More stuff to go wrong IMO, but could delay fan enough to stop things cooling down too quickly?

Yeah, that's true. But, that's nature of the animal, isn't it? More electrics/electronics, more things can go wrong.
Efficiency comes at a price, always. I like the idea of a system like Davies Craig with all electric/electronic cooling system, but as you pointed out, the control unit, electric thermo fans and electric water pump add more failure points.
Which, obviously means I can't go cheap on those parts, which is the way i usually prefer to do it with new ideas for budget related issues.
I think, decoding what you're saying above, I leave the things alone as it is for the time being. :D

[dom14]

I was thinking of running a PWM controller for radiator fans on speedway car, a bit more elegant than the bang on bang off of a relay.
Would need a bit of tuning to get gain, derivative & integral mixing right.
Graham

I can only pretend to understand what you were saying above, mate. :)

[Robo]

The viscus fan.
How far does it spin when you give it a good spin by hand 1/4 1/2 3/4 full turn.
Remember a viscus hub thread or read on forum somewhere.
(only spin about 1/3 to 1/2 if I remember correctly! )

[GeeYou8]

PWM: Pulse Width Modulator, a DC motor speed controller that maintains torque, like when you run a cordless drill at low speed you can hear a high pitched whine from the PWM.
Gain:The fan speed for a particular temperature, ie at 60C fan runs at 20%, at 70C fan runs at 60%
Derivative: (Rate) Looks at the rate of change in temperature, so if temperature is rising fan speed increases above what the gain would have set and slows the fan as the temperature.
Integral: (Reset) Increases the fan speed when a steady state higher temperature is detected, so if temperature was 70C the fan would slowly ramp up to 100%(until the temperature starts to drop then the gain & derivative kick in and slow the fan).
Similar to driving a car, we push the accelerator to accelerate then start to lift as we approach the speed we want, then if the car slows we push the accelerator more and more to maintain speed, then lift off as the car exceeds the speed we want.
Graham

[UncleFrosty]

I think, decoding what you're saying above, I leave the things alone as it is for the time being. :D

Nah, not at all. Someone's gotta be the first!!! Just a view from my corner using the KISS principle... ...and a strong, irrational belief in Murphy's Law (esp. when compounded by the tyranny of distance).

[dom14]

The viscus fan.
How far does it spin when you give it a good spin by hand 1/4 1/2 3/4 full turn.
Remember a viscus hub thread or read on forum somewhere.
(only spin about 1/3 to 1/2 if I remember correctly! )

It can spin about 1/4th of a full turn with a good quick spin with hand.

[dom14]

Nah, not at all. Someone's gotta be the first!!! Just a view from my corner using the KISS principle... ...and a strong, irrational belief in Murphy's Law (esp. when compounded by the tyranny of distance).

I think, adhereing to KISS principle is probably a good idea, until I understand the cooling system little bit more. :D
I wouldn't mind an online crash course in Engineering thermo. It's that I'm struggling with time atm. :)

[dom14]

I'm quoting below post from another forum. It's about how to diagnose a fan clutch for any issues.

Fan Clutch test

First, lets discuss what the fan clutch does and why it is there. The fan clutch is just what the name says, it is a mechanism that will clutch the fan on and off depending on the need for more or less cooling air to flow thru the radiator. It is a thermostatically controlled device that when operating normally will vary the fan speed independently of the engine speed. When cruising down the road at freeway speeds, with outside temperature less then desert conditions, the fan should be merely be idling along, turning just fast enough to add a little air flow when needed, in this way the fan noise and drag on the engine is greatly reduced. When reducing speed, the fan clutch will sense higher temperatures thru the radiator and “clutch up” thereby increasing the fan speed to help maintain constant engine temperature. It may in fact, cycle as the temperature of the air thru the radiator changes depending on airflow. If the fan clutch operation is normal, when first starting the car, the fan clutch should “clutch up” and an increase in noise and airflow should be obvious. After about 60-90 seconds, the fan will un-clutch and the noise and airflow will drop. The fan will continue to turn but at a much reduced speed. As the engine warms and the thermostat opens to regulate the temperature, the air thru the radiator gets hotter and the clutch will sense this, thereby increasing the speed of the fan to maintain a normal operating temperature.
First signs of trouble:
A normal temperature indication at freeway speeds and an increasing temperature as the vehicle slows is one of the first indications of trouble. Many other things may give this indication but if the temperature seems to be stable at speeds but climbs in traffic or while stopped, this is a good indication that the fan clutch isn’t working correctly. As the temperature continues to climb, the auxiliary electric fan should start but may not provide enough air to keep the engine from overheating.
Another sign of trouble is if the fan noise is high and never decreases after starting, and is there anytime the engine RPM is higher then idle, this means that the fan clutch is “frozen” and is not releasing. Although this will not result in immediately serious trouble, it will load the engine continually and gas MPG will be reduced. Load on the fan belt(s) will be higher and shorten the life of that component also.
Fan modifications:
It has been suggested that other models of BMW fans can be substituted to reduce the noise and load of the fan. This is NOT recommended! If the fan clutch is working properly, there should be no need to replace with a lesser fan. The noise and load of the fan should only be there when it is “clutched up” and the fan speed needed to keep that big V-12 cool. BMW designed it this way and it is never a good idea to alter the cooling system and in particular where alloy engines would be effected.
Testing the fan clutch:
If you have reason to suspect that the fan clutch is defective, here is the recommended procedure to verify the condition of the fan clutch.

1. Start the car (cold) with the hood open and note if the fan is turning, increase the engine RPM and note if the fan turns faster and the noise increases, if it does, first good indication, if it does not increase speed/noise, clutch is bad and needs to be replaced. (Remember, this must be tested after the car has been off for and extended period, over night etc.)

2. Leave engine running and note if the fan starts to slow down after 2-5 minutes, speed/noise should diminish and even raising the RPM, the fan should not make as much noise as when first starting, if it does slow, this is the second good indication. If speed/noise does not decrease, clutch may be “frozen” and should be replaced.

3. Leave the engine idle and watch the temperature indicator. When normal operating temperature has been reached, some increase in fan speed/noise should be noted, in particular when the RPM is increased. If temperature is fairly stable and the fan noise/speed increases or cycles, third good indication. If temperature indication continues to increase, with no increase in fan noise/speed, clutch is defective and should be replaced.

4. After the engine is at normal operating temperature or above, is the only time that the “rolled up newspaper” test that many people talk about should be performed! Take some newspaper and roll it up into a long narrow tube. Be carefull, keep hands and fingers away from the fan while performing this test! With the engine at full operating temperature and idling, take the rolled up paper and insert it on the back side of the fan and try to reach the hub of the fan avoiding the blades until close to the hub. Push the rolled paper at the fan increasing the friction to the hub area of the fan. If the fan can not be stopped easily this is the fourth good indication, if it can be stopped the clutch is defective and should be replaced. Again, this test can only be performed when the engine is at or above full operating temperature.

Testing can be performed in any order but just make sure the conditions during testing are those that are specified for that specific test.
Do not continue to operate the engine if the temperature continues to rise and certainly stop if the temperature approaches “redline”.

[Robo]

It can spin about 1/4th of a full turn with a good quick spin with hand.

Only 1/4 turn, its should be ok then, going by the spin by hand test.