Leakdown testing:

Folks,

Does anyone have a guideline for analyzing cylinder leakdown results?

How do you determine if you have lousy piston rings or excessive valve leakage?

Thanks,

Rog

where is the air coming out?

for example, the dipstick probably means rings (or piston :()

belteshazzar wrote: where is the air coming out? for example, the dipstick probably means rings (or piston :()

this. put your ear by the intake to listen for bad intake valves, and likewise with the exhaust. if its very drastic it could be something like a bent/burnt valve, a slow and/or intermittent leak could point to a spinning seat. the best advice i can give is use your logic

With the leak down tester installed listen for the air leakage. In the intake, intake valve(s). Hear the hissing in the exhaust, exhaust valves. If you remove the oil cap and hear it, then it's the rings. Sometimes the sound is tough to hear, in that case, do a wet test. Same as compression testing, if the leak down is less (compression higher) with some oil poured into the cylinder, then it means the rings are in question.

I think the baseline is nothing over 20% leakdown.

If this is from your spitfire engine, then, take off the oil filler cap. Listen, hear air escaping/whistling? Bad valves. Pull the dipstick, feel/hear air? it's the rings. Make sure you do the test on the compression stroke with both valves closed.