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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.
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
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.
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.
Last edited by dom14; 23rd August 2016 at 01:38 AM.
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.
Last edited by dom14; 2nd September 2016 at 12:50 AM.
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?
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. )
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.
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.
Last edited by dom14; 2nd September 2016 at 01:40 AM.
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.
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.
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.
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
Last edited by dom14; 23rd August 2016 at 02:07 AM.
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.
Last edited by dom14; 2nd September 2016 at 12:52 AM.
Originally Posted by GeeYou8
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