Ill start with what is done to the car: Z6, T3 turbo, Oem head gasket (2K miles), ARP studs (2K miles), OEM water pump (2k miles), OEM timing belt (2k miles), OEM thermostat (4k miles). JDM obd1 B16 ecu. Stock heat range NGK spark plugs. obd0 to obd1 conversion worked great with the P28 ecu that is at phearable being chipped. No CEL ever present on the P28. Drove it 1600 miles to VA and back at the beginning of April. No engine issues the entire trip.

B16 ECU throws a code to which I try to check but do not get any flashes. It lights solid. Car runs terribly bad when the CEL is on, both before and after the turbo install. It runs as if the timing is off and does not accelerate well at all when it is on.

Today I get the car up and running. Finished putting all of the turbo equipment in and fire it up. Still running the JDM B16 ecu. The VW Scirocco radiator does not have a fill neck so I pour coolant in the upper hose until it spills a little out than connect it to the neck on the front of the head (did this before I started it.) Idle is good, no leaks.

I go to take the car to the muffler shop to have them weld up the rest of the exhaust. I get a decent coolant leak but the car does not overheat. I leave there to return home. I give it a little gas after warming it up and bring the boost gauge to -1 inches vac and the CEL comes on. Car runs bad and I noticed that the temp gauge shoots up near "H" when putting the car under any form of load without going into boost. I pull off and pop the hood. No coolant pouring into the overflow bottle, a drip of coolant every few second from previously mentioned leak. Upper hose is hot. Lower hose is hot, but you could still hold onto it without risk of burning yourself like you would on the upper hose.

Flat tow the car home. Check oil, looks as fresh as it did when I opened the bottle. Drain coolant. Swap radiators. Put in an EG half rad with 12" slim fan and shroud. Fill with coolant and let it idle, without the radiator cap on to bleed the system, for about 20ish minutes. All is well. Fan is wired to ignition switch so its on anytime the key is on. Temp gauge never exceeds 3/8.

Leave to go to the gas station. Pulling up to a red light about 1/4 mile from my apartment the CEL comes on. Temp gauge still at 3/8. Turn onto main road giving a little throttle (vac gauge at -3 inches) and the temp gauge starts to rise quickly. Pull into gas station, temp gauge at 3/4, turn car off but leave ignition on so the fan stays on. Again, upper hose too hot to hold, lower hose hot, but you could hold it without worry. Overflow bottle has coolant past the "max line" almost near the cap. 3 minutes later I start the car. No CEL, temp gauge sitting at about 1/4. Leave gas station to return home. Go very easy on the car. Rpm's never exceed 2200 or so rpm and vacuum never exceeds -6 inches. Did have to go up a small hill putting the car under a slight load. CEL stays off the entire ride home and the temp gauge never exceeds 3/8. Get home and all seems to be very well.

I think I cooked the head gasket but am not sure since nothing seems to be repetative. Closest to boost I have gotten is -1 inches vacuum on a brand new Autometer gauge. The temp gauge goes past the halfway mark only when under a load and only when the CEL is on. The car cools down from 3/4 to 1/4 in 3 minutes. However the last time it got hot there was coolant going into the overflow bottle. No water in the oil, no foam or anything in the radiator cap or overflow bottle. No smoking from anything in the car. No smoke out of the exhaust which is 2.5" downpipe, flexpipe, resonator, turn down under the back seat. Upper radiator hose is too hot to hold, Lower radiator hose is hot but you could hold it without burning yourself. Car has never Warmed past 3/8 until these 2 instances today and that is with either ECU and even with the B16 ECU and the CEL on putting the car under a load prior to the turbo install.

I am going to bleed the system again tomorrow and refrain from driving it until my p28 comes in. I would like to convince myself that its a combination of the B16 ECU and air in the coolant system, but really believe I blew the head gasket some how. Anyone have any insight as to what they think the issue is, or wish to confirm my thoughts?

 

it is possiable that maybe you are getting air pockets in your coolant so it makes air pockets which tend to heat up the motor, but not to that extreme, also i think the ecu has to do with it alot, maybe it was badly programmed or has been tampered with before you bought it. this is a tough and odd situation your dealing with. i hope someone has some more insight on this. good luck

 

wait till the ECU comes in and see if anything changes. you might need to replace the HG if your boosted and overheating (even tho youve not seen any boost yet). Usually the air pockets go away after bleeding the system. Good luck and let us know if you get it figured out.

also i think your not getting any codes cause its a JDM ecu?

 

it really sounds like theres air in your coolant lines but the CEL. hmmm...