Hi there I've got a track Evo9 (Ex Garage HRS car) with a Evo8 Tomei crate engine running Tomei H11 studs,Tomei 1.2 stopper head gasket, and all the go fast bits for 450 WHP Arms 7693 turbo, 272 Poncame etc. After a couple of track sessions I noticed the water temp exceded 110 deg C. Nursing the car back to the pits water temp went back to 85 deg C and after it cooled sucked all the remaining water from the overflow tank back into the radiator that it didnt chuck out when out on the track, When cooled I added atound 1.5 Litres to top it up to where it should have been.
On idle when hot it pushes out and sucks back coolant when cooling as it should. This just seems when driven hard. Its got a big alloy race radiator which keeps it cool at around 85 Deg C when out on the track, and has always been purged of air. Oil cooler and track oil temps of no more than 120 deg C
Car has a new water pump, coolant lines and runs water wetter with de mineralised water, and radiator is shrouded and cooling fan works fine with a 1.3 bar radiator cap
Thermostat opens at 92 deg C.
No water in oil or oil in water, no steam and car idles and runs fine.
Compression 170 PSI +- 5 PSI across all cylinders when hot and throttle open.
Thoughts and reccommendations?
Thanks for reading :-)

 

i believe i have/had this issue, but during a dyno session. the shop pressurized the cooling system but no sign of leaks. we're hoping its just the old Skunk 1.3 bar cap. this was the first time i didnt idle the car while topping off the radiator tho. I just didnt have enough time. fingerscrossed.

 

I'm hoping its just the thermostat and changing to a high flow one that opens around 65 Deg C... Rather than 95 Deg C would help, as it never gets that hot on the track.
We made sure air was purged from the radiator (Big funnel that was over fill and let the water displace bubles when thermostat opened on idle

 

If you have “disappearing” water from the cooling system then it’s most likely leaking.
I would do the bleeding procedure again and try and test again. Another option is to use a compression leak test kit, this detects hydrocarbons in the cooling system.
Basically, if you have hydrocarbons in the water/coolant, then you know your head gasket is compromised

https://amzn.to/3GTbC6h

 

yup looking into that too today

 

we used this kit too. It turned out my radiator separated at the bottom, we were not sure if this is the cause or the effect. i brought my old radiator and the car seems fine now but when they used this kit it indicated its picking up fumes but very little (dark blue turned dark green, but not yellow). now the builder wants to replace the headgasket and (assuming the gasket arrives monday), we have 1 day to get it done. i hate that test kit lol

 

Cheers Blake, pretty much waht we were thinking too :-(

 

If you have that much coolant loss without a visible leak, and you're not seeing white smoke out the exhaust, I would bet a good amount of money an old/defective cap is at least part of the problem. Late last year I was chasing a decent-size leak (losing probably around 250ml per week, daily driven street car) with no evidence of leaking that I could find anywhere. Replacing the cap solved 95% of the problem, I'm guessing the remainder is a very small leak in the radiator itself that is evaporating before it reaches the ground.