david.perl
Well Known Member
Rapid drop in Cylinder compression -exhaust valve culprit
I have a Lycoming IO 360 M1B engine with 350 hours of air- time on it over six years. The number one cylinder was giving a slightly low compression reading of 68 psi. We could hear that the air was escaping from the exhaust valve during the test.
The engineer suggested I run it hard for an hour or so in-flight which I did and we then retested within 10 minutes of landing whilst the engine was still hot. The compression on the cylinder dropped to 61.
We left it for a couple of hours and the compression dropped further to 54
I have a Lycoming IO 360 M1B engine with 350 hours of air- time on it over six years. The number one cylinder was giving a slightly low compression reading of 68 psi. We could hear that the air was escaping from the exhaust valve during the test.
The engineer suggested I run it hard for an hour or so in-flight which I did and we then retested within 10 minutes of landing whilst the engine was still hot. The compression on the cylinder dropped to 61.
We left it for a couple of hours and the compression dropped further to 54
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