Porsche Track Car Part 18 – Engine Problems

My last outing of the year in the Porsche 944 track car was at Carolina Motorsports Park (CMP).  It did not go well in that the engine started spewing water out of the coolant pressure tank on the 3rd lap and, at idle, I had a knocking sound from the engine that didn’t sound healthy.  I was able to drive the car back into the pits and on to my trailer.  I towed it home and came back for the Sunday portion of the HPDE with my E-Type.  Yes, I know it sucks to have an E-Type as my backup car but sometimes life really does give you lemonade instead of lemons!

Interestingly enough, when I started up the cold 944 and drove it off the trailer, everything seemed fine.  The next weekend, I started it up and after it was warmed up a little the knocking noise appeared again at light throttle.  At that point, I decided it was time to start my winter R&R effort.

In one very long Saturday effort I had the engine pulled and torn down.  I found that the #2 rod bearing had definitely spun.  I had never seen a spun bearing before but it was pretty obvious. The “tangs” on the bearing shell that locate it were torn off and the bearing shell was worn down to a reduced thickness.  The journal on the crankshaft was also scored.

I also suspected that I had overheated the engine in my last session at VIR.  I checked the cylinder head with a precision straight edge.  I found it to be warped about 0.006″ at the #2 combustion chamber.  This may not sound like much but it is 3 times the Porsche allowable spec value.

My premise is that the head was warped at VIR, then when I got the engine up to temperature at CMP I had a head gasket breakdown that introduced water, combustion gases, and oil to each other in a very negative way!  I’ll never know for sure.

I did a little research and decided to trust my machine shop work to T-Hoff in Raleigh, NC.  I had 2 good used crankshafts so they are simply going to evaluate the best one and clean it up to put into service.  They are going to do a light skim cut on the head to get it flat.  They are going to put in new valve guides and do a 3 angle valve job.

In the meantime, I am going through the entire drivetrain and suspension.