No compression cyl #5 need advice
 

:confused:
Today I took my 1976 930 out for a drive. After driving a half hour, I visited a friend for a cup of coffee. I started the engine and it was still hot. After 5 minutes I took her for a fast acceleration in 2 gear and I took her all the way up to the rpm limits cuts off the engine. I have done that many times, of course only when the engine is warm, I know the head studs could break. But after this acceleration engine starts to make a weird sound. Like a pft pft pft and a tik tik tik tik noise from the left side of the engine, and is as the car only drives on 5 cylinders. There was ignition at all the spark plugs. I did a compression test, NO compression cyl #5!! S Car Go Racing did a rebuild 8k miles ago with 3,2 cylinder and Mahle pistons, 993 twin turbo head studs.

Is there and suggestions what could had happened?

Burned piston?
Burned or broken valve?
Broken head studs?
Broken rocker arm?

Best Regards
Jesper Damm

best to do a leak down test instead of guess.

if i had to guess i would say you bent a valve.

Check the rocker arm
If overrev, there could be a broken rocker arm.
Normally it would give great leak test, but it could be stuck and holding the valve open.

That happened to my previous 930 when I missed a gear shift when accelerating.