A little background first, a 94 with 83,000 miles but for the last 13 years, the stock engine has been mostly track driven around NorCal. I drive up there, hopefully beat on it for 1 1/2 hours and drive home. I'd estimate it's got over 200 track hours between 4000 and 5800 RPM. The engine has been very reliable......until my last time out.

The car overheated on the track big time; I smelled the coolant first and by the time I looked down it was 270F. There was tremendous blowby in the cooling system and when I pulled the plugs, water poured out of #5. Compression tested out at 120-130 in every cylinder after a lot of cranking with throttle open.

When I took the intake manifold off, there were broken teeth and small bits from the cam sprocket that drives the water pump gear in the intake galley mostly near #1 and less near #2. As I looked through the machined holes in the front of the block, I could see broken gear teeth. I believe the car overheated because the teeth that drive the water pump broke off. When I drained the oil, water poured out first but there wasn't that much metal on the magnetic drain plug; mostly gear teeth but some other funny stuff too.

Well, here's the part I don't understand yet. When I pulled the heads(had to cut the fricken steam tube!!) I fully expected to see the head gasket near #5 breached but it's totally intact! The other gasket didn't show any breach either! No obvious cracks on the heads or block. Water in the oil, exhaust in the coolant; where is it coming from?

 

If the gaskets are solid, and no cracks in the block, the entry of
coolant into the oil system may have been allowed by warped heads
(??).

 

Thanks, that makes sense.