Engin's running too cold?

Hey Guys,

My RB30(Carby dual fuel) was kinda running bit too 'cold" yesterday, if I'm correct about that.
I was driving for about couple of hours in the evening and the temperature gauge doesn't seem to be
going as high as it usually did.
It's a fairly cold evening last night, for around 4-5 degrees in Melbourne, but
I've never seen the temperature gauge dial going this low even in colder days, after driving for that long.
I was running the heater on and off, but I do that in winter anyway.
I did "fiddle" with AFR mixture screw on the carby to get the petrol to run previous days back, but it wasn't
running on petrol yesterday and won't be for a while. So, it was on LPG.
It didn't make much difference whether I was stationary on idling or doing 80km/h on the highway.

I didn't think carby AFR setting mattered that much for LPG anyway, or does it?
LPG mixer has it's on AFR setting which I've never touched.

So, I didn't think the engine's running bit cold due to running too rich, or is it possible with my "fiddling"
with carby AFR screw??!!

When I started and warmed up before I took off yesterday for the drive, the engine was purring initially,
but didn't sound like as much purring on the highway. Kinda sounded bit rough, while I was keeping any eye on the seemingly low
temperature reading on the temp gauge.

So, I'm guessing,
1)Running too cold/too rich possibly due to my carby "fiddling" with the mixture screw? or
2)Coolant thermostat is in early stages of dying?

I took the picture while idling after I got home yesterday.
It idles around 950-1000rpm on LPG atm. I don't seem to be able to get it down to 850ish, warm or cold on LPG
Any advice please guys?

Thanx

thermostat is morethan likely sticking open a bit and letting the coolant flow too much at low temps

Cold weather does weird things to these carby motors mate!

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Originally Posted by Throbbinhood

Cold weather does weird things to these carby motors mate!

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I would agree Dom. From what I have been reading about your weather over there, I would just let it go untill you have a big thaw and see if the temps come back to normal. And BTW, your correct in the GAS AFR is set in the regulator.
Cheers Tony

Was the heater temp hot when in the hot position or luke warm.
Just saying as mine takes ages to get to temp lol

Remember trucks used to have a blind in front of the radiator grill to maintain temperature.

It's been cold here and worse down your way according to my sister in law, so could be down to ambient being so low.

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Originally Posted by Throbbinhood

Cold weather does weird things to these carby motors mate!

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Absolutely mate. Especially, these old beat up carbies can't handle sudden cold weather fluctuations.

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Originally Posted by threedogs

Was the heater temp hot when in the hot position or luke warm.
Just saying as mine takes ages to get to temp lol

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Nah, it's kinda annoying, 'cos when I turn the heater all the way up, then it was getting too warm inside the car.
I was bit too brain fogged to realize that I could've simple play with the temp control slider to keep the desired temperature inside the car. :)

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Originally Posted by billyj

thermostat is morethan likely sticking open a bit and letting the coolant flow too much at low temps

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Yeah, just to be safe, I reckon I should pull it out soon and test it outside the car with boiling water.

Regardless of outside temperature, the thermostat should not open until the engine is up to temperature. Exactly the same thing happened to my TB45, the first thing I noticed was that on long downhill runs the engine would get slightly colder, changed the thermostat and all good.

I did a good 25 minute drive just before. Temperature still sits at the lower end of the dial reading.
But, I have no trouble heating up the inside of the vehicle via the heater.
I'll have to see how it goes.
Overall, it takes bit longer for the engine to get into the healthy coolant temperature by the looks of it.
I reckon, even in Melbourne cold winder, 10 minutes of driving should be enough for the engine to get to the
healthy temperature, provided the thermostat is doing it's job & the gauge is not faulty.

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Originally Posted by JME_GU

Regardless of outside temperature, the thermostat should not open until the engine is up to temperature. Exactly the same thing happened to my TB45, the first thing I noticed was that on long downhill runs the engine would get slightly colder, changed the thermostat and all good.

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Exactly! That's what I experienced yesterday. I'll replace the thermostat anyway.

I dunno, I get the theory of thermostat keeping it that way..But my rig did the same with an old and a new thermostat. Going on a long downhill run it'd cool down a bit. My old Hilux did the same. They'd do the same if I just left them idling for ages, they'd just keep cooling down slowly. I don't know if once open, they don't close fully until a certain point or what, but it hasn't worried me.

What I have noticed now is that the auto choke (which I've had issues with previously, but thought i'd adjusted it enough to sort it) I believe is coming back on after a drive in cold weather, as it idles high for a bit when I come back to a standstill until the carby seemingly warms up a bit again and the idle lowers. Might wind the auto choke off a bit further.

Having just fitted an extra water temp gauge, I can tell you
the after market gauge and the Ecu-Talk are pretty even
BUT when the OE dial shows the motor at running temp it is in fact
only 60-70 degrees on the gauges, well below my 85-88 operating temp
Hope that made sense lol

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Originally Posted by Throbbinhood

I dunno, I get the theory of thermostat keeping it that way..But my rig did the same with an old and a new thermostat. Going on a long downhill run it'd cool down a bit. My old Hilux did the same. They'd do the same if I just left them idling for ages, they'd just keep cooling down slowly. I don't know if once open, they don't close fully until a certain point or what, but it hasn't worried me.

What I have noticed now is that the auto choke (which I've had issues with previously, but thought i'd adjusted it enough to sort it) I believe is coming back on after a drive in cold weather, as it idles high for a bit when I come back to a standstill until the carby seemingly warms up a bit again and the idle lowers. Might wind the auto choke off a bit further.

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Yeah, playing with the auto choke can help during the Melbourne winter, or any season in Melbourne, considering we tend to get all four seasons in a single day sometime.
But, RB30 and TB45 electric auto choke is not that smart or effective all the time. Auto choke opens up by heating bimetal coil electrically via alternator trigger line activated auto choke relay, not by responding to engine, carby or intake air temperature. Once the auto choke flaps are opened, it tend to stay that way. AFAIK, the the bimetal spring doesn't unwind itself in cold weather to cause the mixture to become richer. This is why sometime it can help turning the auto choke either way, depending on the weather/climate.
It is possible to improve the auto choke further to make it more "intelligent" to respond to intake air temperature and engine temperature, but I reckon the effort is probably put into a better use with an EFI conversion.

Quote:

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Originally Posted by threedogs

Having just fitted an extra water temp gauge, I can tell you
the after market gauge and the Ecu-Talk are pretty even
BUT when the OE dial shows the motor at running temp it is in fact
only 60-70 degrees on the gauges, well below my 85-88 operating temp
Hope that made sense lol

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So, I shouldn't take the OE dial reading as accurate?
I do have an aftermarket coolant temperature gauge with an alarm buzzer, but have never got around to install it.
May be it's about time I install it.

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Originally Posted by dom14

Once the auto choke flaps are opened, it tend to stay that way. AFAIK, the the bimetal spring doesn't unwind itself in cold weather to cause the mixture to become richer. This is why sometime it can help turning the auto choke either way, depending on the weather/climate.

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Thanks for the info Dom. Hmm, interesting. Might have to do some tinkering. Something's definitely going through a hot/cold phase though, just not sure what. Anyway, I think you've had enough of my hijacking your threads :P

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Originally Posted by dom14

So, I shouldn't take the OE dial reading as accurate?
I do have an aftermarket coolant temperature gauge with an alarm buzzer, but have never got around to install it.
May be it's about time I install it.

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The OE gauge isn't very accurate, and the ones that are are still lazy. I've installed a gauge, with the reading coming from the top hose. It's much faster to respond and gives me a much better idea of what's going on.

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Originally Posted by Throbbinhood

Thanks for the info Dom. Hmm, interesting. Might have to do some tinkering. Something's definitely going through a hot/cold phase though, just not sure what. Anyway, I think you've had enough of my hijacking your threads :P

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Nah, it's good you brought it up. As far as hot/cold hiccups with RB30, I reckon you explained it pretty well above with RB30 carbies are prone to quirks with sudden weather changes. It's probably not possible make them run perfect in every weather situation. Probably, some tinkering with the choke and tuning may be necessary from time to time.

I had the same issue with my tb45. Thermostat wouldn't close all the way, stayed open about 2 mm. Once replaced all good. Just got back from driving around in tempts that didn't pass 8 degrees during the day and tempts were fine.

Sent from my XT1068 using Tapatalk

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Originally Posted by jay see

I had the same issue with my tb45. Thermostat wouldn't close all the way, stayed open about 2 mm. Once replaced all good. Just got back from driving around in tempts that didn't pass 8 degrees during the day and tempts were fine.

Sent from my XT1068 using Tapatalk

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But it did get to normal operating temp didnt it ?????lol

@dom14 heres some 12mm "Ys" for your gas system , they will make your system
more efficient with less cavitation, If you need 10mm yell out as I have a link for them as well

http://www.ebay.com.au/itm/281878696...%3AMEBIDX%3AIT

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Originally Posted by threedogs

But it did get to normal operating temp didnt it ?????lol

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Yeah, with the new thermostat. When the old one was in it took longer to get to temp and when driving in he mornings during winter the tempts dropped only when on the freeway.

Sent from my XT1068 using Tapatalk

I recommend you test the new thermostat before fitting it as I have had a brand new one fail.

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Originally Posted by mudnut

I recommend you test the new thermostat before fitting it as I have had a brand new one fail.

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Was it an OEM or aftermarket one?

After market. But I still check any that I have bought since the failure.

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Originally Posted by mudnut

After market. But I still check any that I have bought since the failure.

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Ok, cool. I just remembered. I have two spare ones hiding somewhere. One is brand new, but can't remember whether it's OEM or aftermarket.
The other one is a used one I pulled out from a R31 Skyline from PickaPart few years ago. I just have to find them. :)

What is your method of testing them? Is it possible to test them on a bench that they function at the proper temperature rating?!

most would just place in a pot of water and bring them to the boil.
I have a good working OE thermostat here if required???

Just boil some water with the unit in it and watch it open, then close when you take it out. It just lets you know it won't get stuck as you can't pressurise the water to get the temp above 100 degrees.

Quote:

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Originally Posted by threedogs

most would just place in a pot of water and bring them to the boil.
I have a good working OE thermostat here if required???

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I'll see if I can find the ones I'm suppose to have here somewhere. If not, I'll drop in. :)

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Originally Posted by mudnut

Just boil some water with the unit in it and watch it open, then close when you take it out. It just lets you know it won't get stuck as you can't pressurise the water to get the temp above 100 degrees.

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If I understood you correctly, a pressurized test may be necessary to be conclusive?!

I have a pressure cooker, but I can't see what happens inside.
I guess, I can let the pressure vent quickly( and safely ) and see whether the thermostat stays stuck open afterwards?!

Wouldn't the thermostat be fully open before 100c anyway? As such you won't need it to be pressurized to see it's full range of movement and where it gets stuck.

Edit: looking online, rb30 thermostats open at 76.5. I can't find what temp they are fully open. Highest I've seen on my gauge is 84, which was towing a trailer up a long hill on a 43c day, at which point the clutch fan kicked in and brought it back down. It normally sits between 78-80 unless she's copping a flogging, then she goes to 82c.

Yep. Dom, please don't get too technical. It is just to see that the mechanism moves freely. After I got stuck on the side of a highway with a boiling engine, I test the thermostats to see if they open. I'm sorry I mentioned the pressure.

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Originally Posted by mudnut

Yep. Dom, please don't get too technical. It is just to see that the mechanism moves freely. After I got stuck on the side of a highway with a boiling engine, I test the thermostats to see if they open. I'm sorry I mentioned the pressure.

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Ok, cool. I've never seen how exactly the thermostat performs it's task. I presumed it opens up incrementally to control the temperature.
So, I thought other than getting stuck open, they can go faulty other ways as well.
Of course, I should do the boiling water test before getting into any more details.

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Originally Posted by Throbbinhood

Wouldn't the thermostat be fully open before 100c anyway? As such you won't need it to be pressurized to see it's full range of movement and where it gets stuck.

Edit: looking online, rb30 thermostats open at 76.5. I can't find what temp they are fully open. Highest I've seen on my gauge is 84, which was towing a trailer up a long hill on a 43c day, at which point the clutch fan kicked in and brought it back down. It normally sits between 78-80 unless she's copping a flogging, then she goes to 82c.

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Thanx for posting the above info mate.

Do you have an aftermarket temp gauge fitted?
Shouldn't the "healthy" temperature be bit higher than 84?
I've been thinking all this time it should be around 90 degrees or so.

Another question popped into my head is that I haven't been aware the fan clutch is a temperature controlled type.

Can you please confirm it mate?

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Originally Posted by dom14

Thanx for posting the above info mate.

Do you have an aftermarket temp gauge fitted?
Sure do. I've never trusted the stock ones in any of my fourbies. They're just too lazy, often by the time they start reading hot, your already well over 100c. My old hilux once got to 130c on my aftermarket gauge, the dash gauge only showed 3/4.

Shouldn't the "healthy" temperature be bit higher than 84?
I've been thinking all this time it should be around 90 degrees or so.
Not too sure, but it's the right thermostat for the motor. As long as your using the recommended oils it shouldn't be an issue. Newer motors often run at higher temps. I for one am happy it runs so cool anyway.

Another question popped into my head is that I haven't been aware the fan clutch is a temperature controlled type.
Yeah they are temperature controlled. There is a bimetal spring type thing on the fan. Not sure how exactly it works, but when this heats up it causes the clutch fan to start locking up. So after a good flogging mine will come on for 30 seconds to a minute depending on how hard she's copped it and how hot it is, once it cools down the clutch goes back to slipping and it slows down and goes quiet.

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Quote:

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Originally Posted by mudnut

Yep. Dom, please don't get too technical. It is just to see that the mechanism moves freely. After I got stuck on the side of a highway with a boiling engine, I test the thermostats to see if they open. I'm sorry I mentioned the pressure.

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Dont be sorry. I'm glad you mentioned it. We need to understand these things properly, so we know what we are doing, as we are not professionals in this field.
How the pressurized system works, as opposed to nonpressurized cooling system is pretty interesting.
I'm hearing the idea that we need to replace the thermostat more frequently than we do. Mine hasn't been touched for nearly four years.