js86944

I've looked to see if anyone has had this issue but have found nothing online. After the car reaches near operating temperature I can see air bubbles coming through the head studs and not sure what to make of it. I bled the cooling system and ran the car again and still air bubbles from the head studs. Also, light white smoke from the exhaust after a new head gasket (2nd new one). I'm stumped and it seems to me the only way to find out what is going on is to pull the head off again .

CorsePerVita

the head studs shouldn't have any air coming through them unless contamination from the combustion chamber is getting past a gasket and getting up past the threads. white smoke = coolant.

so you've done 2 head gaskets, was anything done prior to installing them? (machine work etc)

Almost sounds like you've got a high spot or a low spot on the head or block if you've done 2 gaskets, did you have either machined and measured prior to doing this? Had the car overheated at any point? etc..

also - when you did the gasket, did you use new head studs/bolts?

limerocket

I recall seeing this before after torquing down the head, and I wrote it off to residual assembly oil being present on the threads being pushed out due to air pressure communication from the cavity around the headstud in the block through the threads. There is a spiral leakage path along the threads and heat will build pressure in gasket sealed stud cavity. Make a determination of what the bubbling fluid is before you tear into the engine again. If it is assembly oil, it will dissipate like mine did.

js86944

The head was done by LR - nothing done to the block except cleaning. I'm not sure if the car has overheated in the past. All I can tell you is that when the head first came off, it had to have been the original head gasket because it was in bad shape - failed on cylinder 4. The water pump was also original - rusted to hell. There was coolant contamination everywhere.

The first new head gasket did not seal around cylinders 2 and 3 if I recall correctly as evidenced by water found on top of the pistons on disassembly and scarring shown on the head surface. This second head gasket has me stumped with the symptoms I stated in the original post.

Is there anything I can do before I disassemble again? It's not a big deal taking the head off - it only took me 3 hours last time - will probably go faster this time. However, the issue is spending money again on another head gasket and going down the same road when it seems that the issues is somewhere else.

js86944

This makes sense to me and I will grab a q-tip to determine what it is, I had not thought of it being oil from assembly.

CorsePerVita

i believe Cometic MLS gaskets are reusable and last I checked they did make them for the 944.

Aside from what lime suggested, once you find out what it is, if it doesn't dissipate and you end up with issues and end up having to do the gasket again.. make sure you double check to make sure there is no highspots/lowspots. one easy way is to take something flat and level but soft (you don't want to scratch/dent/hurt the head) and see if it's level from one end to the other and see if it's flat, or if it can move/rock you can also visually see if any low spots are there that way. aside from a machinist looking into it. if you do not for sure know if everything is flat/smooth/good to go and it's questionable, it may be worth your money and time to have a machinist at least inspect it (some will inspect it for free) to make sure that may not be causing issues.

limerocket has a good point though if it's something that could dissipate like oil etc. usually white smoke is coolant though.

aren't head gaskets fun!