Exhaust valve problem options
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- blsewardjr
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Exhaust valve problem options
During my annual this week my mechanic discovered that my #1 cylinder had a compression of 45/80 warm. Upon borescoping it he found that the exhaust valve was showing early signs of wear. Faced with pulling the cylinder to the tune of several AMUs, he offered the option of "lapping" it. The operation was successful, getting the compression up to 63/80 cold. We're going to look at it again in 25 hours. My mechanic runs a podcast on aircraft maintenance and I was the subject this week. If you're interested it's at http://airplaneownermaintenance.com/109 ... od-option/ Bernie
Bernie Seward, IR, AGI
2003 DA40 N377DS
KCHO Charlottesville, VA
2003 DA40 N377DS
KCHO Charlottesville, VA
- waynemcc999
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Re: Exhaust valve problem options
At my last annual, I had a burnt exhaust valve... decided to replace with a new full cylinder kit at cost of $1200 parts and a few hundred dollars labor. At the time the aircraft had 1800 tach hours and that was the first valve problem and therefore first cylinder replacement.
Last edited by waynemcc999 on Sat Feb 09, 2019 10:40 pm, edited 1 time in total.
Wayne McClelland
PPL/IR, 2008 Diamond Star DA40-XLS 40.922, KSBA
Photo logs of PilotsNPaws | Flying Doctors | Angel Flight | YouTube @GeezerGeekPilot
PPL/IR, 2008 Diamond Star DA40-XLS 40.922, KSBA
Photo logs of PilotsNPaws | Flying Doctors | Angel Flight | YouTube @GeezerGeekPilot
- blsewardjr
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Re: Exhaust valve problem options
650
Bernie Seward, IR, AGI
2003 DA40 N377DS
KCHO Charlottesville, VA
2003 DA40 N377DS
KCHO Charlottesville, VA
- Pilot55
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Re: Exhaust valve problem options
Usually the valve seat problem starts with valve guide wear. The valve now does not stay concentric with the seat and when the valve is seated does not make enough contact with the seat to pull the heat out of the valve. It also puts higher point loading on a smaller area of the seat and causes the seat and the valve to pound out in that area. The lapping will help for a period of time but if the seat is worn it will return.
- blsewardjr
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Re: Exhaust valve problem options
Bret- That what my research revealed as well so I had my mechanic check the guides. He says he didn't find any slop in them. That said, I agree that the problem will probably eventually return. Nonetheless I'm trying to follow Savvy's Mike Busch's advice to do whatever you can before pulling the cylinder. Busch believes that pulling cylinders can, if you're not extremely careful, result in much more serious engine problems. See
https://www.savvyaviation.com/wp-conten ... afraid.pdf Bernie
https://www.savvyaviation.com/wp-conten ... afraid.pdf Bernie
Bernie Seward, IR, AGI
2003 DA40 N377DS
KCHO Charlottesville, VA
2003 DA40 N377DS
KCHO Charlottesville, VA
- blsewardjr
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Re: Exhaust valve problem options
We did the re-check and as Bret predicted the valve guide is now very wobbly and low compression has returned. We’re going to pull the cylinder. Any experience with re-build vs Lycoming vs Superior vs ECI? Thanks. Bernie
Bernie Seward, IR, AGI
2003 DA40 N377DS
KCHO Charlottesville, VA
2003 DA40 N377DS
KCHO Charlottesville, VA
- Steve
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Re: Exhaust valve problem options
Sorry, can't give any advice about what kind of cylinders...
Lycoming recommends checking the valve guides every 400 hours on our engines. I've only done it once (at around 500 hours, and it was OK). There is a Lycoming SB to do the test:
It requires the use of a ridiculously expensive tool. I, being an inveterate eBay surfer, was able to get one for much less than the list price several years ago:
If anyone needs to do this SB, and their mechanic doesn't have the tool, I would be willing to loan it out...
Steve
Lycoming recommends checking the valve guides every 400 hours on our engines. I've only done it once (at around 500 hours, and it was OK). There is a Lycoming SB to do the test:
It requires the use of a ridiculously expensive tool. I, being an inveterate eBay surfer, was able to get one for much less than the list price several years ago:
If anyone needs to do this SB, and their mechanic doesn't have the tool, I would be willing to loan it out...
Steve