Jump to content
SAU Community

Recommended Posts

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

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.

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

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.

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.

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. :)

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 by kwazza11

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.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • I came here to note that is a zener diode too base on the info there. Based on that, I'd also be suspicious that replacing it, and it's likely to do the same. A lot of use cases will see it used as either voltage protection, or to create a cheap but relatively stable fixed voltage supply. That would mean it has seen more voltage than it should, and has gone into voltage melt down. If there is something else in the circuit dumping out higher than it should voltages, that needs to be found too. It's quite likely they're trying to use the Zener to limit the voltage that is hitting through to the transistor beside it, so what ever goes to the zener is likely a signal, and they're using the transistor in that circuit to amplify it. Especially as it seems they've also got a capacitor across the zener. Looks like there is meant to be something "noisy" to that zener, and what ever it was, had a melt down. Looking at that picture, it also looks like there's some solder joints that really need redoing, and it might be worth having the whole board properly inspected.  Unfortunately, without being able to stick a multimeter on it, and start tracing it all out, I'm pretty much at a loss now to help. I don't even believe I have a climate control board from an R33 around here to pull apart and see if any of the circuit appears similar to give some ideas.
    • Nah - but you won't find anything on dismantling the seats in any such thing anyway.
    • Could be. Could also be that they sit around broken more. To be fair, you almost never see one driving around. I see more R chassis GTRs than the Renault ones.
    • Yeah. Nah. This is why I said My bold for my double emphasis. We're not talking about cars tuned to the edge of det here. We're talking about normal cars. Flame propagation speed and the amount of energy required to ignite the fuel are not significant factors when running at 1500-4000 rpm, and medium to light loads, like nearly every car on the road (except twin cab utes which are driven at 6k and 100% load all the time). There is no shortage of ignition energy available in any petrol engine. If there was, we'd all be in deep shit. The calorific value, on a volume basis, is significantly different, between 98 and 91, and that turns up immediately in consumption numbers. You can see the signal easily if you control for the other variables well enough, and/or collect enough stats. As to not seeing any benefit - we had a couple of EF and EL Falcons in the company fleet back in the late 90s and early 2000s. The EEC IV ECU in those things was particularly good at adding in timing as soon as knock headroom improved, which typically came from putting in some 95 or 98. The responsiveness and power improved noticeably, and the fuel consumption dropped considerably, just from going to 95. Less delta from there to 98 - almost not noticeable, compared to the big differences seen between 91 and 95. Way back in the day, when supermarkets first started selling fuel from their own stations, I did thousands of km in FNQ in a small Toyota. I can't remember if it was a Starlet or an early Yaris. Anyway - the supermarket servos were bringing in cheap fuel from Indonesia, and the other servos were still using locally refined gear. The fuel consumption was typically at least 5%, often as much as 8% worse on the Indo shit, presumably because they had a lot more oxygenated component in the brew, and were probably barely meeting the octane spec. Around the same time or maybe a bit later (like 25 years ago), I could tell the difference between Shell 98 and BP 98, and typically preferred to only use Shell then because the Skyline ran so much better on it. Years later I found the realtionship between them had swapped, as a consequence of yet more refinery closures. So I've only used BP 98 since. Although, I must say that I could not fault the odd tank of United 98 that I've run. It's probably the same stuff. It is also very important to remember that these findings are often dependent on region. With most of the refineries in Oz now dead, there's less variability in local stuff, and he majority of our fuels are not even refined here any more anyway. It probably depends more on which SE Asian refinery is currently cheapest to operate.
    • You don't have an R34 service manual for the body do you? Have found plenty for the engine and drivetrain but nothing else
×
×
  • Create New...