Post-Rebuild Pre-Start Compression?

[David Inc.]

Originally Posted by 911 SLANT

I was always told to do leak down with motor hot and after rings have seated. Is this not true?

I think my results were much higher than they would have been hot with the engine fully oiled up, but it helped me to identify inconsistencies between cylinders. When 1, 2, 3 and 5 were all the same at just under 20, but 4 and 6 were ranging from 40-60%, big difference!

[911 SLANT]

You have some very knowledgeable mechanics chiming in on your post Jeff, Ian, ect..Your in good hands.

[Jeff Alton]

Originally Posted by 911 SLANT

I was always told to do leak down with motor hot and after rings have seated. Is this not true?

Ideally, yes. But we leak down the motor to ensure all went well, no broken rings, and valves are seating. Even cold with no miles we see leakage of around 6-12% which tells us we are good to install and start the break in process. Its a quick check to ensure all assembly steps up to that point went according to plan....

Cheers