Compression test - Snowblower Forum : Snow Blower Forums
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post #1 of 3 Old 02-16-2019, 02:21 PM Thread Starter
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So I bought a compression test kit form Amazon. Im getting only 23psi on a cold Tecumseh lh318sa. It's a 9hp snow king.

Is this legit? I understand these engines have a pressure release on the camshaft to allow for easier starting.


I tried the test again using the electric start. I'm hitting 80psi.

Last edited by Harry Doyle; 02-16-2019 at 02:36 PM.
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post #2 of 3 Old 02-16-2019, 03:29 PM
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That's lower than I've gotten on my Tecumsehs, I've had 40-45 with the pull start. Jumping to more like 80 with the electric start. One was an OHV, after just setting valve clearances, and confirming the bore was ok.

Compression releases complicate the readings. You could check your valve clearances. If the exhaust valve clearance is small, the compression release might be opening the valve a bit too far.

Make sure you aren't using any unnecessary adapters. Your want to minimize the air volume that you're adding, by adapters, hose extensions, etc. Any added volume (even the tester itself) will give artificially lower readings then what the cylinder sees.

And keep pulling until the reading stops rising, don't just pull once, for instance.

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Last edited by RedOctobyr; 02-16-2019 at 04:30 PM.
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post #3 of 3 Old 02-16-2019, 04:15 PM
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I agree with RedOctobyr 100%, I can't add anything, just confirming what he said to you other than as long as its starting fine, it's ok. When the valves, especially the intake, starting becomes harder.

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