1994 Integra GSR, OEM Rebuild, P73 pistons. Engine break-in complete. High rpm pull through 1-2 gears, car starts to overheat badly. I pull over and shut down engine, restart immediatley and temp starts to fall back down to normal. Happens every time. Coolant gets forced out of reserve bottle everytime.

other than that, car runs fine all day, daily driving. No coolant leaks, no coolant/oil contamination, no smoke, residue, normal plug and cylinder colors. no problems before rebuild. car and components are in excellent shape.

what do you guys think? leaking headgasket under high pressure?

 

Yup.

Mis-torqued headbolt sounds like the culprit.

 

so i'm guessing that high pm combustion pressure leaks into the cooling system, forcing all the coolant into the reserve and out of the bottle. the cooling system has insufficient coolant level, thus overheating.

But what about when i turn the emgine off for a sec and restart, the temp cools down to normal?

Any other theory?

 

well, i gonna rule out headgasket, i had my shop pressure test the cooling system and held fine, no water/oil mixture. i wonder what it could be? like i said the car runs fine idle and daily drive, fuel mixture is fine, fans run, new water pump and mugen low temp thermo.

 

Hey John, I bled the sytem for an hour. but the whole time, I keep getting continuous air bubbles. Where could all the air be coming from? Anyway, I put the cap back on and drove around slowly, brought up to bout 5-6 rpm slowly, and began to overheat....., after i got home and popped the hood found the reserve bottle full of coolant, (it was at min when i started). Thanks for your help.

 

Perform a compression check to reexamine that head gasket. If the compression is uniform, then check your thermostat.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by andyrew500 &raquo;</TD></TR><TR><TD CLASS="quote">well, i gonna rule out headgasket, i had my shop pressure test the cooling system and held fine, no water/oil mixture. i wonder what it could be? like i said the car runs fine idle and daily drive, fuel mixture is fine, fans run, new water pump and mugen low temp thermo.</TD></TR></TABLE>

Don’t rule out head gasket yet. A cooling system pressure test may not show a small leak in a head gasket. The cooling system pressure test is MUCH lower pressure than what happens inside a cylinder. When you rebuild your motor did you re-use your head bolts? I found on my race car (stock B18b1) if I re-use my head bolts I will get some combustion leakage past the head gasket at high rpms, and get a similar situation(I push out about 1-2 cups of water per 30 min) You’re only going to see coolant in the oil if you have a large leak of coolant into your cylinders.

BTW unless your ECU is tuned for the lower temp Thermo take it out.. your just confusing the ECU and it will never think the car has reached operating temp.

 

thanks for the advice, i am using Arp's headstuds