Carl Froehlich
Well Known Member
I'm helping a neighbor work and engine problem. The plane has been idle for several months and he is getting it ready for conditional inspection. The compression check for #1 cylinder is 5/80, the other three cylinders are in the mid 70s. There is perhaps 300 hours on this engine.
Bore scope showed nothing of interest. The valves and valve seats look fine, and both valves are fully closing. The cylinder walls looked normal. I could find no cracks on the cylinder head or barrel (some areas are obscured).
On engine run up the engine is smooth and all four cylinders CHT and EGTs are tracking (as in normal temps). After a long high (for the ground) RPM run we did the compression check again and it was still at 5/80.
I can hear the air leaking out of the cylinder and noted that a little air was coming out the #3 cylinder spark plug hole (plugs were removed for compression checks).
My only guess are the rings have failed - but I would have expected to see some evidence of this on the cylinder walls.
Other ideas?
Recommendations for next step?
Carl
Bore scope showed nothing of interest. The valves and valve seats look fine, and both valves are fully closing. The cylinder walls looked normal. I could find no cracks on the cylinder head or barrel (some areas are obscured).
On engine run up the engine is smooth and all four cylinders CHT and EGTs are tracking (as in normal temps). After a long high (for the ground) RPM run we did the compression check again and it was still at 5/80.
I can hear the air leaking out of the cylinder and noted that a little air was coming out the #3 cylinder spark plug hole (plugs were removed for compression checks).
My only guess are the rings have failed - but I would have expected to see some evidence of this on the cylinder walls.
Other ideas?
Recommendations for next step?
Carl