TOOSLO5

Could not make up my mind where to post so here goes. My 98 with a D1SC, Patriot heads and Cometic gaskets is having some issues, but only under boost. I can run the car all day unless I get into 2-3 lbs of boost or higher. At that point I run into pressurization of the cooling system and start forcing coolant from the radiator into the overflow. I have no coolant in the crankcase.The mods were done by EPP per preivous owner and at the time there were no leaks. This is something that just started recently and I only noticed it when the temp shot up one day after a blast. The temp shot up and would not come back down. After I got home and checked the radiator and overflow I noticed the coolant level was low. I also noticed the overflow tank was full and had overflowed, coolant had been running off of the intercooler hoses under the car. Has any one run into anything like this? Most of The cometic leaks I have been seeing seem to be external not internal.

CHRISPY

Blown headgasket. You'll need to pull the heads (check the heads for straightness and mill very slightly if necessary) and replace the gaskets.

It would also be a good time for ARP headstuds.

Do not beat on the car. You probably need to retune the car as it might be lean detonation causing the headgasket to fail.

TOOSLO5

Engine is already studded and I have never had any KR on the scanmaster but I guess anything is possible. The car was also built by EPP so its not like some kid put the thing together. The engine has only been together in the configuration for about a year and when I purchased the car there was no leak, it just started all of the sudden about a month ago. Isnt that how it always goes though!

Stu'sWS6

iTrader: (3)

I would suggest replacing the headgaskets, checking the heads for straightness and torqueing the arp head studs to 80 to 85 ft-lbs. I have seen the cometics fail when using arp head bolts/studs torqued to 65. It is also possible that you cracked a sleeve
in the block.

Amount of Boost? Injectors/fuel pump? How is the tune? Does the car run as well as it should? At least log some runs and post up the data. I'd probably look into getting the car tuned again if all of the right parts are in place.

TOOSLO5

8 lbs of boost, 255 pump, 42 lb injectors, car was tuned with LS1 edit, very conservative tune. No KR and O2's are usually in the 880 -900 range all of the time. The KR and O2 numbers come from my scan master. Car also runs great unless you get your foot into enough to make some boost, even under boost it seems fine. It just pushes enough coolant to get warm, not hot just a little hotter than the 184-186 or so it usually runs. After some coolant is lost into the overflow the temps will run in the 205-212 range and stay there. If I stay out of boost the temp never goes up past the 184-186 mark.

CHRISPY

You could have any number of things happening to cause detonation and headgasket failure.

1) pump starting to fail causing a lean condition
2) voltage problem to the pump or injectors
3) clogged fuel filter
4) faulty regulator
5) too much timing and too lean AF for summer heat

Let us know when you find out what is wrong.

strokedls1

iTrader: (1)

.880-.900mV on the o2 is way too lean for a blower car. That translates to 13.0-13.2 afr. You need to be around 12.0 to high elevens. Those heads need to come off and see whats going on before you smoke the motor.