Engine Overheating After Prolonged Boost

[kwazza11]

My car has developed the rather annoying problem of overheating when its subjected to lots of high rpm full acceleration. basically its fine in day to day driving, even hot days peak hour traffic it doesnt skip a beat but as soon as i'm in the hills or do a lap or two it starts to cook and if left unchecked will just keep rising! i've tried pretty much everything, thermostat is new, water pump is new, radiator was stripped and cleaned, all hoses were also changed 2 months ago, tried different coolants, oil cooler, fully wrapped exh, manifold, turbo and oil lines insulated etc. nothing seems to help.

so i got thinking and thought mabye theres air being pushed into the cooling system through where the manifold butts to the head, i know its a long shot but has anyone heard of this happening?

would the pressure difference be enough to blow the gasket? 14psi boost v 12psi rad pressure...

any oppinions/ideas?

Cheers

Karl

[Al]

How much is the temp raising to?

[Pablo]

Is the radiator a factory match to the engine?

By the way, there is a LOT more pressure than 14psi in the engine... 14psi is just the pressure of the air being taken up into the engine. once it is in the cylinders the pistons then compress the fuel/air mix.

[kwazza11]

just using the stock temp gauge for the moment and it gets to 3/4 to full and to the point of boiling in the overflow tank if i'm not quick enough to shut it down.

radiator is 10-15mm thicker than the one that initially came on the car

as for whether its entering through the combustion chamber, well i'll do a gas test on the coolant tomorrow and see what i get from that.

[blind_elk]

Are you still running the factory fan?

Do you still have the small undertray under the radiator?

Do you have a thick FMIC?

Any other things not "factory"?

[PHATR32]

yeah i was gonna say that the fan wasnt mesnioned in the items replaced.

maybe the clutch is shot?

steve

[Roy]

yeah i was gonna say that the fan wasnt mesnioned in the items replaced.

maybe the clutch is shot?

steve

I dunno...but a fe things you may want to look at are, like someone else said the clutch fan. Also you have an R31, and their front bars arent great for airflow. So how big is the intercooler up front of the radiator...can you be sure you are actually getting decent airflow up there?

Lastly the tune. My car was tuned 'conservatively' for a period of time. It ran hotter then usual in traffic and when up it, it got hotter a lot quicker. Turns out the ignition was retarded so much that the A/F mix was still burning when the exhaust valve opened throwign a lot of heat into the water jacket. Well that was the theory and when i had the car re-tuned with the if it "blow it blows tune" it ran much cooler.

Could be a combinaiton of all these things

[Bl4cK32]

well mine sits at just over half on the temp gauge. But the factory gauge can be misleading, as just over half can mean anywhere from 82 - 105. Only then will it go up to the overheat )top of the line)

Might be something simple like my car is experiencing atm. I can run around no porbs, but if i go for a long drive with the overflow full, itll bubble out, and suck it all back in.

Solution i think is that the radiator cap is old and needs replacing as it isnt holding pressure in the cooling system properly.

[Ceffy_SA]

Thats an interesting problem you have. I have had the same sort of problem with my RB20DET A31 Ceff, as soon as i installed a large'ish intercooler i found that when thrashing the car through the hills the water temp would rise quite a bit and get close to boiling point.

Turned out that it was my std clutch fan that was not engaging anymore due to it being worn out, i replace that which solved all my troubles.

Still the std water temp gauge in my experience is hardly accurate, i just purchased a Auto Meter water temp gauge, and basically when the std gauge hits half way the autometer gauge is reading around 72-75 Degrees.

[grim32]

Did you bleed the cooling system properly when changing the radiator and the hoses

[ferni]

What kind of power are you making (helps to know so we have some idea of the heat being created)... Bigger HP car will create more heat.

[Cubes]

Still the std water temp gauge in my experience is hardly accurate, i just purchased a Auto Meter water temp gauge, and basically when the std gauge hits half way the autometer gauge is reading around 72-75 Degrees.

I see the same with the pfc connected.

Half is anywhere from ~72 right up to 109degree's. I quite like the stock guage like this to be honest. Nothing worse than a stock temp guage that constantly reads up and down.

[Busky2k]

Yeah I think the whole reason why the needles in factory cars like to sit rock solid center is so that the varying conditions dont worry a n00b driver.

[kwazza11]

Are you still running the factory fan?

Do you still have the small undertray under the radiator?

Do you have a thick FMIC?

Any other things not "factory"?

The car has a 16" thermo fan mounted 5mm back from the radiator with the OE shroud, but its just a cheap repco jobby so probably not the best for flow, intercooler is a modded 33 GTR one so not overly thick and yep the undertray is still there.

Lastly the tune. My car was tuned 'conservatively' for a period of time. It ran hotter then usual in traffic and when up it, it got hotter a lot quicker. Turns out the ignition was retarded so much that the A/F mix was still burning when the exhaust valve opened throwign a lot of heat into the water jacket. Well that was the theory and when i had the car re-tuned with the if it "blow it blows tune" it ran much cooler.

Could be a combinaiton of all these things

could be a winner on that one, the car is tuned very rich (mid 10s past 5k) and havent checked the timing up top, still waiting on a certain tuner in adelaide to get Fcon V software before i can do much about that though... :

will get it back on the dyno this week and get the timing checked and see if anything can be done.

Did you bleed the cooling system properly when changing the radiator and the hoses

yep!

Cheers

Karl

Edited March 24, 2006 by kwazza11

[blind_elk]

In my expeience, thermo fans are the primary cause of these engines overheating when pushed. Partucularly when combined with FMICs that weren't there in the original design of the cooling system.

Put the factory fan back - it's not worth an engine for the few kW a thermo fan releases.