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Exhaust valve bore scoping


kmyfm20s

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@alextstone posted a thread showing his exhaust valve failure. I also attached an article from Mike Busch. In the article he says you should be able to identify a failure 100 to 200 hours before it happens. I didn't want to add all this to his but felt like others would like to see it. 

https://www.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2010-08_exhaust-valve-failures.pdf

I scope at every oil change and while I'm there I do a compression check and rotate my spark plugs. I wanted to show how great bore scope photos come out doing it on your own. I went down and took these just this afternoon after reading his thread. These valves have 578 hours on them. I will look up the name of the camera but it has been mention here before.

WIN_20200329_17_20_55_Pro.jpg.7a68c82ad6d7a2e2d88feca8f69317c1.jpgWIN_20200329_17_27_55_Pro.jpg.0ac038f2e74856108c71fae3a44fc682.jpgWIN_20200329_17_37_02_Pro.jpg.09e457740349d79a8dac115572aae8ac.jpgWIN_20200329_17_45_44_Pro.jpg.449d6828d3dd5f014d1450c89eb62638.jpgWIN_20200329_17_48_35_Pro.jpg.39b496225e2901ad78529304e0ecb70b.jpg.WIN_20200329_17_09_05_Pro.jpg.ee1262b1e63535beb2f085d077b3b6de.jpg

 

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Great pics, k!

The nice circular pizza image on each valve is key!

When the valve stops rotating, the hot spot shows up on the edge... and grows inward over time...

The ability to scope each cylinder each time the plugs come out is really interesting.

Uneven cooling, / uneven heating... can change the shape of the part, and the strength of the metal...

 

Thanks for sharing the details... :)

Best regards,

-a-

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4 hours ago, MooneyMitch said:

Yes, please do let us know the camera equipment

Often the Vividia Ablescope VA-400 is mentioned.  If you buy via Amazon, remember to include the Amazon Smile donation to the Mooney Foundation.  But do wait for kmyfms20s to share which camera was used before buying.

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I’ve never scoped my own engine until last week, prior done my MSC and have no clue what I’m looking at. My friend who helped me does his and thought mine were fine, any response would be greatly appreciated 

CC6DB7A5-1CE9-4FA3-8694-3DDA2868103A.jpeg

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8786EF84-F60E-4401-9AAF-170B627AE14A.jpeg

75222584-91EB-45E7-9182-A5ACC7B63DAB.jpeg

3A28F14B-1C42-458C-B9F2-663E09DC51A2.jpeg

5BF3CA69-B2E6-4F91-9F97-2D268E75D874.jpeg

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5 hours ago, tmo said:

Often the Vividia Ablescope VA-400 is mentioned.  If you buy via Amazon, remember to include the Amazon Smile donation to the Mooney Foundation.  But do wait for kmyfms20s to share which camera was used before buying.

Same here, great resolution and bright pictures posted by KMYFMS20S.  I also use the the VA-400 but my pictures never look as bright or detailed as those posted, so maybe it is not just the camera used but also the software used. 

My valve pictures look more like yours, which by the way do not seem to indicate any abnormalities, assuming you are showing the four exhaust valves and not one or more repeats of the same exhaust valve(s) from different orientations. The two intake valve pictures appear to show some but not abnormal carbon deposits.

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My technique,

  1. Preform on cool engine (lens can fog if engine is hot)
  2. remove top plug only ( I find if both plugs are out and it’s bright outside picture quality is hazy)
  3. position piston in the down position, bottom dead center
  4. clean lens and make sure it illuminated 
  5. Insert camera and turn lens 180 degrees.

 

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2 minutes ago, MooneyMitch said:

Thank you.   Another question please.....what end equipment and app are you using please?  

Your laptop will have a camera app built in for the built in camera. You will have to select the USB camera from the built in camera.

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8 minutes ago, kmyfm20s said:

Your laptop will have a camera app built in for the built in camera. You will have to select the USB camera from the built in camera.

Thank you.  No laptop, but I do have Android SamsungTablet A.  Per Amazon information, that should work. 

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@Danb

Things to look for...

Six exhaust valves are the most important... they get the hottest...

Check the circular pattern the carbon build up makes...

  • looks like a pizza, good...   waves from something dropped in the center...
  • looks like some kind of edge effect...  waves from something dropped near the edge... (not so good)

Of the six valves in your post...

Four have good round pizza looking pics... one is hard to see a good portion of the valve... and the last doesn’t have the usual pizza image...  (was that an exhaust valve?)

intake valves are usually cleaner, as they get washed with cool air and fuel...

overall no bad edge effects noted...

For improvements... next time... try to get the whole valve in the pic... to see all of the edges... :)

PP thoughts only...

-a-

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Just now, MooneyMitch said:

Thank you again.

I use a free android app called CameraFi2.     There is an older version called CameraFi, and either works.    It's a generic app and works with my good Vivia Ablescope as well as the $20 cheapie endoscopes that I keep around.

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FWIW, I use VLC (VideoLAN) both on tablet and laptop (Ubuntu, but also available for Windows).  Not sure about i-devices (Apple).

If possible, I'd like to resume the main subject - can those with experience tell the rest of us what to look at on the most representative valve pictures?  I know it is all in the EAA article, but specific examples are priceless.

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Typical exhaust valve...

pizza look...

 

4158C449-B468-4208-9B5F-6239159861F0.jpeg
 

Very symmetrical...

note the intake valve in the pic... nice and clean...

Extra cleanliness is typical of being new or flying LOP...

 

Alex’s chipped valve...

note the strong edge coloration caused by no longer distributing heat evenly...

The chip probably happened after the edge discoloration began...

Alex’s data only showed a flight or two where this may have begun... it was Not hundreds of hours...

52BAC93B-CEE3-492F-BE85-13FAEDE96A48.jpeg.82d0b7a2cd03c48245706294632efb7c.jpeg
 

some oddities in the pics... mirror images up the cylinder walls are funky... views out the spark plug holes are funky as well...

 

Alex flys a TC’d Lycoming and K has an NA Continental...

PP thoughts only...

-a-

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Here is my #2 exhaust valve from last October. While I was bummed to have to install a new cylinder I was happy that it was discovered via inspection, at home. No performance problems and not AOG at a far away location.

Larry

WIN_20191025_16_57_55_Pro.jpg

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On 3/30/2020 at 6:26 AM, Danb said:

I’ve never scoped my own engine until last week, prior done my MSC and have no clue what I’m looking at. My friend who helped me does his and thought mine were fine, any response would be greatly appreciated 

CC6DB7A5-1CE9-4FA3-8694-3DDA2868103A.jpeg

 

CC8EC677-0D7B-4F19-B6C9-986A1D519AC4.jpeg

 

 

 

3A28F14B-1C42-458C-B9F2-663E09DC51A2.jpeg

 

Your photos above show beginnings of exhaust valve seat erosion. Note the clear areas where the valve meets the seat. 

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Philip and Rich... and others...  (general question)

 

 

When valve seat erosion occurs...

1) was there a way to avoid this? Or it just happens while operating an engine?

2) Can Dan use the standard method of changing out the valve seats and guides (valve, valve seat, guide...?)

3) does that get done as needed, or do all six sets because this is wear that is occurring similarly to all cylinders?


PP thoughts only, I have very limited knowledge at this depth.... :)

Best regards,

-a-

 

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1 hour ago, carusoam said:

Philip and Rich... and others...  (general question)

 

 

When valve seat erosion occurs...

1) was there a way to avoid this? Or it just happens while operating an engine?

2) Can Dan use the standard method of changing out the valve seats and guides (valve, valve seat, guide...?)

3) does that get done as needed, or do all six sets because this is wear that is occurring similarly to all cylinders?


PP thoughts only, I have very limited knowledge at this depth.... :)

Best regards,

-a-

 

All good questions. I don’t have enough data to call myself an expert. It would be good to talk to a tech at a cylinder shop. 

Ive heard that poor alignment of the rocker arm can accelerate valve guide wear. I think these decisions have a lot to do with how much time is left on the engine. 

I would just fix the bad one and keep an eye on the rest.

That being said, once you take enough stuff off to pull one cylinder, it is easy to pull the rest.

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