[steve25]

Sorry but the tool has its place for certain and especially if you use it on all of your motors cylinders just after break in and then every 1000 miles in terms of a street motor it provides good guidance.

If you don’t think that using it has any merit then your left with what you read with cylinder pressure measurements and making very accurate compression ratio calculations.

[Schurkey]

Originally Posted by steve25

Sorry but the tool has its place for certain...

...If you don’t think that using it has any merit then your left with what you read with cylinder pressure measurements and making very accurate compression ratio calculations.

I've been doing cylinder leakdown testing since about 1988-ish. For decades, I used a Snap-On MT324 single-gauge leakdown tester. It was unusually sensitive--Iron Duke-powered cars would drive into the shop and show 80% leakage on the cylinders. Newly-rebuilt engines would show ~20% leakage. (Eventually, I found debris in the main orifice. Once cleared-out, it began giving results more in-line with the other leakdown tester.)

In 2012, I bought an aviation-style two-gauge unit with a Continental Teledyne-style Master Orifice built-in. The Master Orifice helps to "test the tester"; and to calibrate expectations.

I never said that leakdown testing wasn't useful. I said that picking out a percentage number and saying that it was "good" or "bad" didn't make sense. Because that number depends on both the actual leakage AND the construction of the test equipment, the test equipment itself can skew the results--the INDICATED leakage. And typical automotive leakdown testers have NO standardization for the crucial component--the main orifice.