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  #1  
Old 04-18-2022, 10:56 PM
jcarne's Avatar
jcarne jcarne is offline
 
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 2,346
Question Sulfur deposits on exhaust valve?

Soooo... having a borescope is a gift and a curse at the same time.

Would this yellowish-greenish area on the valve be sulfur deposits? It shows up on #3 and 4 but not 1 or 2. Also only shows up inside exhaust passage and not on the face of the valve.

Anyone know if this is an issue? I'm guessing not but I don't know what I don't know. Thanks!
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  #2  
Old 04-19-2022, 06:11 AM
BH1166 BH1166 is offline
 
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If it is, nothing u could do about it right? Lean always till it hurts… change oil regularly. Fly often. Quit the playing with the scope…:-)
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  #3  
Old 04-19-2022, 09:25 AM
larryMar larryMar is offline
 
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Location: C77, Il
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Great clarity! What set up are you using?
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  #4  
Old 04-19-2022, 09:49 AM
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BillL BillL is offline
 
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#1 - you can not depend on the color rendering of the scope to be accurate. If you want to get a scare look at your throat.

#2 - It is just lead deposits.

#3 - don't get too excited about what you see in the scope until you have some more experience. Keep posting . . .

#4 - the resolution IS really good, is it the new VA-400?
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  #5  
Old 04-19-2022, 10:42 AM
gasman gasman is offline
 
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Location: Sonoma County
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If you want it to look like new....... Just run Propane....

plus, it's only 4.2 lbs per gallon. But the weight of the tank makes up for it...
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  #6  
Old 04-19-2022, 01:19 PM
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jcarne jcarne is offline
 
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Location: Worland, Wyoming
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Thanks for the replies guys, I'm just trying to learn as much as I can when using the borescope and it seems the only way to really do that is ask people with more experience than myself. Just seemed odd that it appears on the back two cylinders and not the front.

Normally wouldn't scope this cylinder but I'm checking each oil change now to see if my exhaust valve is rotating on #4 or not.

The scope is a VA-400 I purchased about a year ago. Never did look to see if it is their new version or not.

Quote:
Originally Posted by BillL View Post
#1 - you can not depend on the color rendering of the scope to be accurate. If you want to get a scare look at your throat.

#2 - It is just lead deposits.

#3 - don't get too excited about what you see in the scope until you have some more experience. Keep posting . . .

Bingo, that's why I keep posting my pics, just trying to learn

#4 - the resolution IS really good, is it the new VA-400?
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Last edited by jcarne : 04-19-2022 at 01:21 PM.
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  #7  
Old 04-19-2022, 07:52 PM
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Greg Arehart Greg Arehart is offline
 
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Very little chance it is sulfur. Sulfur is quite volatile at low temperatures so unless your CHTs are in the 200 degree range any sulfur would go out the stack. Since its an exhaust valve, highly unlikely it would be at temperatures low enough to condense sulfur. My semi-informed position as a geochemist that dealt with sulfur for many years.
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  #8  
Old 04-20-2022, 08:04 AM
TAB TAB is offline
 
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Location: Florida
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Default CHT

Check the CHT on each cylinder at cruse, they should be +/-10 degrees of each other. I balance the CHT by trimming or adding aluminum tape to the inlet baffling at cylinders 1 and 2 (lycoming). Your back cylinders may be hotter than the front two; add tape to the front baffling. The factory RV baffling is very well designed and should only require a 1/8" to 1/4" adjustment across the cylinder to make a 20 to 50 degree difference. It takes a couple of iterations to reach an even temperature across all cylinders. You should notice the valve look the same once you achieve equal CHT, provided all cylinders are the same age.
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  #9  
Old 04-20-2022, 09:04 AM
von_flyer von_flyer is offline
 
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Location: Metamora, Michigan
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This will make you feel better...
(not mine)
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  #10  
Old 04-21-2022, 10:16 AM
rongawer rongawer is offline
 
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Location: Brentwood, CA
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Quote:
Originally Posted by jcarne View Post
Soooo... having a borescope is a gift and a curse at the same time.

Would this yellowish-greenish area on the valve be sulfur deposits? It shows up on #3 and 4 but not 1 or 2. Also only shows up inside exhaust passage and not on the face of the valve.

Anyone know if this is an issue? I'm guessing not but I don't know what I don't know. Thanks!
It appears to be a loaded up valve (carbon and lead combustion byproducts). As others have mentioned, brutally lean the engine on the ground - to the point that it stumbles in ground idle, and then just add a touch of mixture to keep it running. Ground idle is the main culprit in fouling plugs and valves due to the lower temperatures and cylinder combustion pressures.

A couple hours of running at full power should help clear it up, but as long as compressions are good, I wouldn't worry about it. Consider running LOP.
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