I just did a leakdown test on my 2.0L 12.5:1 engine. I used a Snap-On gauge. I turned compressor on and set the gauge to 100psi. Connected it to the enigne and the needle for leakdown percent stayed below 0%. Does that mean everything is OK? I was able to hear the air inside also though and VERY VERY VERY faintly able to feel some of it come off the crankcase, I mean I had to sit there for a few minutes before I was sure if it was air. The thing that I don't understand is why I felt the air? Is it just to relieve it self like crankcase pressure? The leakdown needle stayed under 0% the whole time and never showed any signs of leakage.

 

Were the valves closed on the cyl. you were checking? Posible if intake valves were open that some air could go threw the evac and into the motor.

 

Valves were closed, positive of that. It was at TDC and valves closed. I even did a rotation of the engine to make sure, when the valves oped the leakdown read 100%, it had so much pressure I couldn't even rotate it back to TDC. Everyone I've talked to so far has told me a little air blow by is fine, I'm not talking a whole lot, VERY VERY little. I even upped the pressure and it still read 0% leakage.

 

Anyone else?

 

Just getting a little past the ring gaps. Happens on most motors. Haven't tryed it on a gapless ringed motor yet.

 

I just redid it setting the PSI to 100psi before putting the gauge on. After I did that it read:

1- 1.5%
2- 1%
3- 1.5%
4- 1.5%

This engine only has around 10 miles on it also so I don't know if the rings are fully seated, I had people follow me when I was driving it and no one ever saw any type of smoke or smelled anything. I think I'm in the clear now.