My new Leak down tester faulty?

PTmowerMech

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Using the new leak down tester. Read the instructions a couple of times. Watched a couple of video's til I thought I had it down.

First off, warmed the engine up, than drained the air compressor to about 90lbs. Then without pulling the valve covers, I put my thumb over the spark plug hole until it was pushing air out, found TDC with a pencil in the plug hole.
Hooked up the tester as it says, with a wrench on the fly wheel to keep it from turning, the reading on the cylinder leak side stayed in the "SET" position It dropped off of zero a little. Right on the 10% mark.

Funny thing, I can hear air from the oil fill tube on both cylinders. A steady flow of it. So shouldn't the cylinder leakage gauge show it actually leaking?

What am I doing wrong here?
Open the valve all the way, hook up the air hose to it. Turn the dial to zero. Then plug into the hose going to the plug hole.
 
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StarTech

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If after setting the tester to zero and it is now showing 10% leakage rate then the cylinder are good and tight. The air you here is normal as some air will always leak pass the rings due to the end gaps. The last Briggs twin that I did a leak down test registered 10% too on both cylinders. Now that; of course, was after I loosen the overly tight valves (a couple with zero clearance) the leakage rate was 80%. But normally I see a lot of 15-20% on fairly new engines.

If you are worry about the tester not working set it @ 10% and if you now get a higher leakage rate.
 

PTmowerMech

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Gonna switch this over to the thread this is about. Here.
 
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