Quote:
Originally Posted by lvporschepilot
Also note that different leakdown testers can post different results. An older Snapon Mt324 is the most sensitive tester I've ever seen, and any number under 15% is great with that particular tester. Same cylinder tests at 6% with a different brand 100psi tester.
Let's not all beat ourselves up over leakdown testing being under 5% etc too. The FAA leakdown standard is very specific, anything under 25% is airworthy using a tester with a .040 aperture and 80psi. The lower the psi tester, the higher the leakage shown on the guage is my experience. So a 15psi tester showing 20% leak is not the same as a 100psi tester showing 20% leak, they will show totally different results. It's all a bit fuzzy using such low psi as well considering peak power is generally over thousand psi in any given cylinder, so how is just 80-100psi going to tell us much. It's better than nothing, just keep an eye on peak power and oil burning.
But I digress;yes, you can expect a difference once the rings have seated and everything is up to temperature.
|
Yep, the question is really about leakage before rings seat...
I did the test to make sure there wasn’t something absolutely wacky, like one cylinder with 50% leakage or something...
Was using a higher end tester...
At low psi, there was very little leakage, and it went up as psi went up...
For example, at a 40 psi input, cylinder would be 39 psi... at 60 psi, maybe 58 psi...
At 80 psi, perhaps 75 psi..
At 100 psi, 90-96 psi... (4-10% leakdown)...
Oddly, the two cylinder with the 10% leakage had the best leakdown before the rebuild...