ok did the old leakdown test. came out between 10-20% for all cyls. compression is 198-205psi and the motor is 9:1 static compression.


when doing the leakdown i could hear the air coming out of my catchcan with the oil fill cap on, and it came out the oil fill cap hole with it off. ive always done leakdowns with the cap off so ive never heard it from the catchcan before. what would air leaking out of those spots indicate? bad rings? it came out of these places with every cylinder. thanks

 

If you can hear the air coming out of the crankcase, then the rings are the source of the leakage.

Did you get the motor up to operating temp before doing the leakdown? If not, try it again with the motor warmed-up.

 

Yea did you warm up the engine? Built boosted motors run loose clearances so up until it warms up it will have some blow by.

 

wouldn't that be the valves? in the catch can and oil fill cap...
that would be the top end
given the catch can woul leak from the bottom end as well depending on how it is set up...
but i'm dislexic so... i could be wrong on this one...

 

No, you would not hear the valves leaking into the crankcase because they can't.

If the intake valves were leaking you would hear it out of the intake manifold.

If the exhaust valves were leaking you would hear it out of the exhaust manifold.

 

cool thanks for clearing that up

 

motor was warm, coolant was around 170 and oil temp was about 160.

ring gaps are a tad big, .022 top ring and .025 second ring. its a benson sleeved 84mm with cp pistons. bottom end has about 9k miles of 400+ hp, headgasket was changed once.

 

Isn't .022 a little tight and cause blow-by?

 

yeah 20% seems a tad on the high side but if its not getting worse rock it.

 

the compression hasnt gone down at all. leakdown was about 10% when the motor had 1000 miles on it, so it got a lil worse. im not planning on going to the track or anything with it anymore, just wanted to really see what the air in the catchcan has to deal with.