Variable Leakdown Results
 

I did a leakdown baseline on my recently rebuilt engine (2 k miles, new P&C, rebuilt heads).

3 cylinders were at 0%. One was at 16%. I took the valve covers off, popped the valves, spun the engine around again, always 16%. Had difficulty hearing where it was coming from. Then, rechecking again with pressure at 100 psi, suddenly the cylinder went to 0 % leakdown. 2 other cylinders exhibited this behaviour as well - 15 to 20 % leakdown, and once a certain pressure got reached (80 - 90 psi in these cases), leakdown went to 0 and stayed there on the way back down.

Before I installed new P&C's, I never had this "variable leakdown reading" happen.

Is this a feature of the rings on the nikasil pistons? Is this a feature of fairly new cylinder bores? Is it a feature of my very special "lucky" (cursed?) engine? Anyone else experience this?

Thanks

some freaky thing going on...you could not have a real problem then have it disappear...!
So i am guessing not serious ..Valves too tight?

possible that your first reading was at too low a pressure for the rings to seat.

Now thats a good point !

I like that answer. First, it makes sense, and second, it means nothing is wrong. :)
Thanks!