Another Post On Sticky Exhaust valves.

[bryancobb]

Hey Guys:

A couple of weeks ago I had a cylinder with "0" compression.
Pulled the engine to fix it, and decided to go ahead and get all 4 checked and yellow-tagged.

The cylinder shop had to replace 1 exhaust valve that had a problem. He said ALL of the guides were extremely tight, so he reamed them. I ordered him a NEW table-of-limits from Lycoming.

It said that if you have 1/2" exhaust valves, then it's OK to go 0.003" over the I.D. called out for the guide during the first 300 hrs and 0.001" every 100 hrs thereafter, up to a max oversize. (I don't recall what max was)

He took that into account when he reamed them.

In hindsight, my engine DID give me a few "taps-on-the-shoulder" to let me know something was wrong, but I failed to notice.

Several times during the past 3 years, when in a hover before departing, I'd lose a little power requiring me to set it partially down to get my RPM back. Then it would run perfectly for the rest of the flight.

I just felt it was a little burp so I paid little attention. Well I now think that my tight valves were intermittently having problems closing which would explain the power losses.


Bryan

[richard]

same problem.its the nature of the lycoming engine