There's this car that I know of that has low compression in 1 cylinder. I did a leakdown test on it and sure enough, it was dropping about 30% of the air. As I raised the PSI though, all of a sudden, it sealed up and held all of the pressure. Sticky valve is what first came to mind, but I wonder if a damaged ring could act like that?

 

i would think it would be a valve problem unless the air pressure moved the piston passed some damage in the cylinder.

 

Na, we did it 5-6 times, each time the exact same thing. I doubt I was lucky enough to get the piston in the same spot each time. Also had it in gear with parking brake on.

 

probably a ring to be honest.

 

Very possible!! But I would still go with the valves first. but if your that far apart might as well pull the other head do them all and re-ring the bottom end. You know red-neck rebuild if your broke!!!

 

Redneck it if your not wanting to keep it too long!!

 

valve, repair appropriately.

 

Oil could be spashing it and sealing it up??? I know when I check cylinder I squirt some oil in there to see if it makes a difference in compression. If it does the rings need to be replaced.

 

Oh fudge.....

 

+!