Ok, a couple months ago my son and I started running his '89 Daytona 2.5L turbo intercooled. Head is ported and has +1mm valves. The head was milled for flatness when the valve job was done.
Ran it for several months then the turbo stopped spooling. So we pulled the head and put a stock Garrett turbo on. One gotcha was the compressor housing clocked incorrectly and prevented the head from seating. We discovered this after starting to torque it. Untorqued the head bolts, clocked the turbo and retorqued the headbolts. (also put in a new tank, fuel pump and level sender.) Ran it that way for several days, then just as he got to school one day he noticed a cloud behind him.
The cloud looks white, but it lingers... So I am not sure if it is coolant or oil. He did notice the coolant blowing out of the radiator cap when he popped the hood. I wasn't 100% sure, but sounded like a blown headgasket... So we put a fresh headgasket on it. The headgasket looked ok. There was a lot of oily residue on the exhaust output of the turbo. I also noticed that the turbo had a lot play in the shaft on the compressor side. Looking up stream there was some on the exhaust-to-turbo junction. Pulling the turbo and there was a lot of oil in the exhaust manifold.
So I decided that the turbo was not this problem, but likely would have to be replaced soon. So I moved ahead with putting things back together. Initially thought things were fixed. I forgot to connect the TPS and IAC so the engine was racing (~2500 RPM) and there was a little smoke at start, but it seem to clear up. After connecting the TPS and IAC and restarting the smoke was definitly back...
So on to more diagnostics. I pumped up the cooling system pressure to 10psi. It held for more than 10 minutes. Started the car and noted that pressure did go up to 12psi. Shut the car down and let it sit. 5-6 hours later the pressure in the system was 5-6psi.
So I am thinking that despite the smoke appearing white (ie. coolant) it is actually oil. Then question is what is the source?
My thoughts questions right now are:
Can a turbo sling oil back into the exhaust manifold?
Would a bad valve stem seal cause a lot of white smoke? didn't see much residue in the cylinders, so I am guessing it is not the intake valve stem seals..
Any thoughts or opinions?