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Can you evaluate my boroscope pics?

agent4573

Well Known Member
First annual and I'm questioning one of my exhaust valves. Any input would be appreciated. 175 tach hours on the motor, compressions came back 79/78/78/77 on a cold motor.
 

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Probably just fine. See this article:


"The first sign of a healthy valve is a symmetrical pattern on the valve face.

Unburned byproducts of combustion frequently leave red or orange deposits on the valve face. These colorful buildups tend to be thickest at the center of the valve (where the temperature is relatively cool). The cooler the valve, and the richer the fuel/air mixture, the thicker the deposits are going to be.

Don’t be alarmed by the reddish color of these buildups. As long as the pattern is symmetrical and resembles an overcooked pizza, it’s probably healthy."


And this chart:

 
Appreciate the quick response. I was concerned about the brown deposits on the edge of the valve, but that aopa diagram makes it sound like that isn't a huge concern. The color pattern is symmetric so maybe I'll pull a little fuel out of cylinder 3 and make it run a bit hotter to prevent additional deposits.
 
Everything looks good and great photos. Which horoscope are you using?

Vividia ablescope VA-400 connected to a Pixel 2XL phone. It's usable on any laptop or android phone. Not compatible with iphones or ipads.
 
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Vividia ablescope VA-400 connected to a Pixel 2XL phone. It's usable on any laptop or android phone. Not compatible with iphones or ipads.

They do offer an addon WIFI box that makes em work with iPhones and iPads. Not the best solution but it works.
 
Exh valves look good. However, I do not think that I have ever seen the rust colored deposits on an intake valve. Pretty confident it is just deposits (valves are SS), but a new color for me. Maybe others have seen this. The deposits on the intakes usually range from light beige to light grey. Are you using any additives in the gas?

Larry
 
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Exhaust valves look normal to me. The exhaust you have two pictures of of may be running a little hotter but not on on the heating diameter which is the important area.

Does this engine have the 3 angle valve job on the intakes like the 340?
 
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Hmmm

Third photo, the exhaust valve (that's the smaller valve), there is a brown patch on the lower right edge. Anything asymmetric on exhaust valves is a caution, particularly near the edge. I'd want to keep an eye on this. Maybe re-check that one in 10 hours. If it actually is a problem they can go south quickly.

Engine monitor? If so upload data to a free account at Saavy and see if the EGT signature is happening.
 
They look OK to me. I think that brown patch is just some lead build up. But no harm in checking at next oil change.

Vic
 
Exhaust valves look normal to me. The exhaust you have two pictures of of may be running a little hotter but not on on the heating diameter which is the important area.

Does this engine have the 3 angle valve job on the intakes like the 340?

I'm actually not sure if it's a 3 angle valve job or not. It's a standard build from aerosport, but I don't know if I ever actually asked them this particular question. I'll email Darrell and find out. What's special about a 1 vs 3 angle valve job for what you're seeing in the pics?


Third photo, the exhaust valve (that's the smaller valve), there is a brown patch on the lower right edge. Anything asymmetric on exhaust valves is a caution, particularly near the edge. I'd want to keep an eye on this. Maybe re-check that one in 10 hours. If it actually is a problem they can go south quickly.

Engine monitor? If so upload data to a free account at Saavy and see if the EGT signature is happening.

They look OK to me. I think that brown patch is just some lead build up. But no harm in checking at next oil change.

Vic

Our hot cylinder is 4, and the one with the funny build up is cylinder 3. Temps have been pretty consistent since break in, but I'll look into the Saavy account. The brown patch is what I was mostly concerned about. Our engine monitor is a g3x, so I'll have to go back and see what has vs hasn't been logged. The 10ish hours previous to the annual we're all spent on formation training, so a lot of low altitude, running rich, throttle transients. I'll pull this plug at the next oil change and see if it's changed at all.
 
The more informed can correct me if I'm wrong, but I don't think there's necessarily a correlation between "hot cylinder" and exhaust valve issues. I'd actually think a leaking exhaust valve (if you had one) would result in cooler CHT as some of the heat is leaking out. Anyhow that's my hunch.
 
The more informed can correct me if I'm wrong, but I don't think there's necessarily a correlation between "hot cylinder" and exhaust valve issues. I'd actually think a leaking exhaust valve (if you had one) would result in cooler CHT as some of the heat is leaking out. Anyhow that's my hunch.

The aopa article on the first few posts seems to indicate there's a correlation between the "crust" buildup and a cold cylinder. I don't think there's a significant difference in our cylinder temps, but no air cooled engine is ever perfectly balanced. We also had some cooling issues during break in, and still do during the summer, but overall we're operating where most of these should be.
 
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