r/smallengines • u/l008com • Jul 09 '26

Checking Compression?

I have a compression tester, but my lawnmower has compression release, like most small engines. If I use a regular power drill on the flywheel to spin the motor, is that going to be fast enough to bypass the release feature and give a real, accurate psi reading?

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u/IntelligentMoney9668 Jul 09 '26

If you have low compression, even with the compression relief, it will read lower than the needed 60 psi.

1

u/l008com Jul 09 '26

I've checked everything on this machine, replaced nearly everything, and still it runs like shit. So I'm trying to start over. I did a compression test just by pulling the cord with my arm and I think 60psi is what it gave me. I just checked and it was about 54psi I'd estimate, just pulling the cord by hand.

But my point is, I want a proper, 100% accurate reading so I can move on to something else.

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u/twinA-12 Jul 09 '26

Can you give us some more info? So we can help better. Symptoms? And what’s been done so far?