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What does bad compression sound like?

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Old 12-28-10, 09:13 PM
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What does bad compression sound like?

As above, what sounds does a rotary with poor compression on a rotor make?
Old 12-28-10, 09:20 PM
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usually no sound at all on the face with bad/broke seals. there's no real description of the sound. if u spin one on the starter with plugs removed, u can immediately tell a difference in the pressure of the air coming out of the plug hole on a rotor that differs in compression between faces.
Old 12-29-10, 08:22 AM
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Like money leaving your wallet.

On a serious note it is pretty obvious as mentioned with the plugs removed. By a $20.00 compression tester and find out for sure.
Old 12-29-10, 10:00 PM
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Originally Posted by djseven
Like money leaving your wallet.

On a serious note it is pretty obvious as mentioned with the plugs removed. By a $20.00 compression tester and find out for sure.
can u buy any compression tester
... and where do u find this compression tester
Old 12-30-10, 03:28 PM
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Originally Posted by anees
can u buy any compression tester
... and where do u find this compression tester
Many parts places like Napa will have compression testers, that is a great tool to add to your tool box. You don't have to buy the most expensive one either.
Old 01-01-11, 10:12 AM
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u can use piston engine compression testers. u just need to either remove the schreider valve or hold it in when doing the test. u don't want it holding the compression, it needs to release it. that's the only way to measure the compression on each rotor face.
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Old 01-01-11, 11:54 AM
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LOL...like money leaving your wallet...that was a pretty good description.

On a serious note, I split 2 apex seals out of my rear housing back in spring of '09. It ran on 1 rotor, but vacuum was all over the place (fluttering around 15in Hg) and it had absolutely no power whatsoever, obviously. Trust me, you'll know if you blew a seal that affects compression. :P
Old 01-01-11, 02:52 PM
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my exhaust makes popping noises by it self on a steady idle.
hmm, i can say its like a popcorn popping noise.
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