222 – How an Engine Cylinder Went From 25/80 to 75/80!

Airplane Owner Maintenance - By Dean Showalter

I inspected another A36 Bonanza recently, and one of the cylinder compressions was too low… lower than the minimum prescribed by Continental using the master orifice tool.

I had two options:

Option One: Remove the cylinder for repair or replacement.

Option Two: Make the exhaust valve seal better and improve the compression result in hopes of saving the cylinder from premature amputation.

I chose Option Two.

It was at least worth a try…

… and the result was stunning!

After lapping the valve in place and installing a new rotocoil, I ran the engine again and rechecked the compression.

It was 75/80!

The lowest cylinder on the engine was now the highest cylinder.

I also lapped the exhaust valve in cylinder #2, and that one improved from 49/80 to 63/80.

If you’d like more info about valve lapping, click here for episode 109.

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Another surprise during the inspection was a cracked / leaking exhaust riser.

Here’s a close-up view of the bad area:

Also in this episode, I talked about some other squawks that were repaired during the inspection. Be sure to listen to the audio for all the details.

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In Part Two of this episode, I talked about our most recent trip in the King Air. It was quite an adventure navigating some weather situations!

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