black951

Hi and thanks for reading. I am having a difficult problem with my 951. I have a 60k block that i recently re sealed and installed in the car with a new head gasket. After about 1500 miles i noticed the car started to run warm- it never overheated just ran warm. the car Ran great- no white smoke out exhaust. i have a wide band and data logged everything carefully- egt and AFR are perfect. im only running 11psi right now. So i bled and bled the car and realized it was not an air bubble. So i did a block test and it confirmed that i had exhaust gas in the coolant system. So i figured that i must have torqued the head down wrong or maybe the head was not flat. no water in the oil- no oil in the water. upon disassembly, i found no evidence of head gasket failure- the plugs even looked ok. i looked around for a crack in the block and found none.
Anyway, i sent my spare good head to LR for a stage one re build with orings and installed it with a steam vent kit. after all this work- i took the car for a spin and discovered it still does the same thing. air bubbles in the cooling system- no matter how much i bleed it- after a hard drive bubbles appear.
I thought maybe it was possible that the gas was going through the turbo water jacket- so i removed the water cooling system temporarily and bled the car thoroughly- no joy- i still have air bubbles in the car. so i tried another block test- and its still a positive for exhaust gas in the coolant (although i did not get around to flushing the car thoroughly so i don't know how accurate this test is). I just tried a compression test for fun and all 4 cylinders are an even 90 psi with the throttle wide open. i know this is a low compression number so im thinking maybe my gauge is off or somehow all 4 cylinders are leaking the same amount (doesn't this rule out a cracked block?). the plugs looked evenly covered in white residue this time- the car is not running lean according to the wide band- and actually its running great- it feels super fast- faster than ever- but it just starts running warm after a while- it has never overheated. bleeding helps once it cools down on idle but then after a bit of hard driving its full of air.
So i am totally at a loss here. maybe my head studs are bad? cracked block? warped block? I really dont want to tear into the head again- as im sure you all can imagine how much fun doing the head is for the third time. but i cant think of anywhere else exhaust gas can mix with coolant. It seems after all this work that the ran runs better (valve job) even though air enters the system faster than before i installed the LR head.
Anyone have any other ideas or something i could have missed? i cant believe this has been so hard- its just a head gasket!! ive been wrenching my whole life. im starting to think this car is just cursed-
thanks for the help!

ilikemy944

Are you getting this 90psi warm?

90 across all 4 is pretty weird...

black951

yes the car was warm- throttle open.....

ilikemy944

Try a different gauge.

I'm thinking maybe some freak pin hole somewhere is letting air into your coolant system - how is coolant pressure after a run? Leaky cap (this sounds rediculous, but...)?

JohnKoaWood

With motor cold, pull all 4 plugs, and pressurize the coolant... repeat on hot engine... pull all 4 plugs... look for coolant leaking into the combustion chambers... maybe a cracked head, with the cracks opening up on a hot engine....

When LR did your head work did they magnaflux or X-ray your head, or just rework it?

Willard Bridgham 3

Did you check the block for square/flat? Did you check the head for square/flat?

Whose head gasket?

Tom M'Guinn

Go to Sears and get their coolant pressurizing tester. Then test the system to see where it is leaking. The cooling system has a fixed volume. Air can't get in for long without coolant coming out somewhere -- either as an external leak or into the bores or oil. I'd guess you have a sneaky leak somewhere that will make itself evident if you pressurize the system to 15psi.

black951

ill try another gauge tomorrow. The coolant pressure seems normal to me. no leaks visible. i would be stoked if i just had a leaky cap- what the heck ill borrow a frends and try it. ill check the pressure tomorrow also.

black951

i tried this test earlier on a hot engine- i could not see any coolant. im going to try again tomorrow with the hot and cold test. im not sure about a cracked head- this is the same problem on 2 different heads- the first was a powerhause head i had rebult myself- the one thats on now is a low miles head i sent to LR. I not sure if there inspection process includes magnaflux or anything else. they claim to inspect the heads before doing the rework.
thanks for the ideas

black951

I did not check the block for square/flat. Is this something that is always done? even when a car has not overheated? i also did not check the head- i assumed that LR would do a good job. in hindsite now i wish i had checked everything out really close. the gasket is victor renz wide fire.

black951

thanks for the ideas, ill get a tester tomorrow. i hope you are right about the sneaky leak. but the block test giving a positive test result for exhaust gas makes me wonder...

Tom M'Guinn

Whenever I have the head off, I check the deck with a precision straight edge. However, if you're problem were a bad head gasket seal, you would see other problems -- one steam cleaned spark plug, heating up after boosting, white exhaust, lumpy idle at start up, milkshake in oil cap, mixing, etc. If you don't have ANY of those symptoms, your head gasket is almost certainly sealing.

This write-up gives some of my tips for pin-pointing a bad gasket: http://members.rennlist.com/tom86951/headgasket.htm

DLS

I have the exact same problem.
my head have been of 2 times and no signs what so ever on the headgasket but still pushes out water
In my case i think it´s either a faulty headstud because that was it the last time or a crack in the head/block.

It would be interesting to see what caused your problem.

boost feen

I would also remove anything needed to check all head studs with torque wrench before going further for teardown. Retighten them all to 5lbs over spec to confirm they are all even and some are not pulling out? Once you crush those head gaskets and use them you cant remove and then reuse and toque down again. At least I wouldnt anyway, Porsche supplies a thinker headgasket however I am not sure its wide fire ring?

black951

Update: bought a pressure tester weds on lunch... it didn't work once i got it home... took it back today... new tester should be in tomorrow.. haha!