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  #31  
Old 01-03-2013, 08:50 AM
jimpappas jimpappas is offline
 
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Default Ouch

About all I can say.... Ouch!!
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  #32  
Old 01-03-2013, 09:00 AM
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Quote:
Originally Posted by turbo View Post
scott, do you have any info on the borescope you are planning on getting. cost, contact? thanks
Sure. I just ordered the first piece of junk off of Amazon that I found. We'll see if it works out with modifications. If not, my plan B is the ATS Borescope, which I may very well get anyway.

Amazon: "Sewell USB IntraOral Oral Dental Camera, 2 MegaPixel, 4 LED"
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  #33  
Old 01-03-2013, 09:04 AM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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While we're on the subject of diagnosing things, can someone provide a link to an engine idiot on HOW to conduct a compression test that might uncover these sorts of things. and thanks!
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  #34  
Old 01-03-2013, 09:15 AM
Rupester Rupester is offline
 
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Location: Mahomet, Illinois
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Default S'cuse me , Bob, but ...

did you want a link TO and engine idiot, or a link FOR an engine idiot?

(sorry, couldn't resist.)
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  #35  
Old 01-03-2013, 09:20 AM
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zilik zilik is offline
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Quote:
Originally Posted by LettersFromFlyoverCountry View Post
While we're on the subject of diagnosing things, can someone provide a link to an engine idiot on HOW to conduct a compression test that might uncover these sorts of things. and thanks!

http://v2.ez.org/cp63-p7.htm

The above link is one of many if you search the internet. Have someone who knows how to perform the DC test walk you through the first time.
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  #36  
Old 01-03-2013, 09:26 AM
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MCA MCA is offline
 
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Well Scott, if you replace the e-bus diode, polish the fetzer valve, and reverse the master switch polarity this should not happen again!
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  #37  
Old 01-03-2013, 10:52 AM
grub0927 grub0927 is offline
 
Join Date: Aug 2012
Location: Newberg, OR
Posts: 18
Default Burnt valve

Scott,
Lycoming exhaust valves have rotator caps that sit on top of valve stem and allow the valve to turn each time it opens. The one darker spot on that valve indicates a place where the valve was not transferring heat to the seat (should be a solid ring all the way around). I'm curious that the valve may have stopped rotating due to build up of carbon in the guide; Lycoming has all sorts of bulletins about sticking valves and reaming guides.
Mike Busch did a webinar for EAA that has info related to exhaust valves and it's worth 45 minutes of your time. I think it was last spring sometime.
Post a picture of the rocker box area around the spring seat so we can see if there is evidence of high heat around the guide.

Keep 'em flying.

Grub
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  #38  
Old 01-03-2013, 11:44 AM
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miyu1975 miyu1975 is offline
 
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so, is the valve replaced or the entire cylinder?
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  #39  
Old 01-03-2013, 12:08 PM
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rv7boy rv7boy is offline
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Quote:
Originally Posted by scard View Post
... That point came this past weekend when Tanya wanted to go do a dog rescue for pilots-n-paws and I said "Sorry, you can't go", as I held my head in shame...

... Feel sorry for Tanya, she has to write the checks .
Scott, I think the least you could have done for her was to rent a Cessna or Piper for her to complete the PnP mission!
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  #40  
Old 01-03-2013, 12:26 PM
grub0927 grub0927 is offline
 
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Location: Newberg, OR
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Default Valve replacement

Ryan,
I think the exhaust valve would be replaced because at 500+ hours the chrome flashing has worn off the valve stem and I suspect has some abrasion from carbon built up inside the valve guide. Guide could be reamed and then dimensionally inspected; if worn it would be replaced. Valve seat should be fine as long it is ground/cut so the new valve has a proper seating surface.
Lycoming's transfer most of their heat through the valve stem as opposed to the seat like a Continental does. Lyc SI 1200A details the need for a very smooth surface finish on the guide so you have good stem-to-guide contact to enable heat transfer.
No need to replace the cylinder, just tidy it up as above.

Grub
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