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My first borescope

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prkaye

Well Known Member
Today I did the 10-hour oil change on my newly overhauled engine (actually IRAN, but replaced all 4 cylinders with reconditioned cylinders). I looked into each cylinder with my new VA400, and took three pictures of each. (1) valves, (2) piston face and (3) cylinder wall.
I think the valves look like they should. Should be concerned that the brownish colour of the cylinder walls indicates glazing? I don't know how i could possibly be glazed- CHTs never got over 400 and i don't seem to have high oil consumption.
Would any of you folks with experienced eyes mind having a look at my images? Links to folders with images for each cylinder on my onedrive:
Cyl 1: https://1drv.ms/f/s!Ai6PWykPTN6oqo5tQJ_tkeiJWALPKg?e=9ZVIjt
Cyl 2: https://1drv.ms/f/s!Ai6PWykPTN6oqo5yuTHT80SD_KDd5w?e=MiEkLm
Cyl 3: https://1drv.ms/f/s!Ai6PWykPTN6oqo52e-9tcbshnxiEYQ?e=ZgIaVt
Cyl 4: https://1drv.ms/f/s!Ai6PWykPTN6oqo56rkA8pSU5n8di8g?e=LW6Wyg
 
I wonder if the brown look is just something with the bore scope. Mine does it too to some degree and I only burn about 1-1.5 qts every 25 hours. Valves look good
 
That's a artifact of the borescope. If they were glazed you'd be using a lot of oil. That's assuming you are past the ring set phase. Oops only ten hours, maybe not yet. Run it hard!
 
Looks like mine do at 35 hours. I changed oil at 13 hours as the consumption was almost nil. I think the rings seated in the first 2-3 hours.
 
Looks like surface rust that the rings have polished off to me. Are the cylinders nitrided or coated like chrome or cermi nil? If coated ignore the rest of this. If nitride, did it sit for a while before you used it? It really looks like rust to me. Black dot or black speckles in the brown would be rust pits, which would mean that the corrosion was a bit worse than just plain surface rust. Couldn't see if any were present with your pics. Either way, if it is rust it kinds looks like it has been polished off by the rings and likely won't be a problem if the peaks of the rust are gone. Pitting won't hurt anything either as long as the rings were not worn to the pint of being a problem. Which is unlikely if your oil consumption is stable and not excessive.
Good Luck,
Mahlon
 
I can't see how it could possibly be rust... these were freshly reconditioned cylinders installed by Aerosport Power about a month ago! They wouldn't have given me rusty cylinders (?), and i can't imagine how rust could have formed in one month!
They're superior millenium cylinders, which i think are just through-hardened steel, nothing fancy...
 
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What borescope are you using? I use a Vividia Ablescope VA-400 and never have any issue with brown artifacts. You could possibly sneek a peek at a small portion of the cylinder walls just looking in the spark plug holes with a small flashllight and see if you see any hint of brown tinge.
 
mahlon_r said:
Looks like surface rust that the rings have polished off to me. Are the cylinders nitrided or coated like chrome or cermi nil? If coated ignore the rest of this. If nitride, did it sit for a while before you used it? It really looks like rust to me. Black dot or black speckles in the brown would be rust pits, which would mean that the corrosion was a bit worse than just plain surface rust. Couldn't see if any were present with your pics. Either way, if it is rust it kinds looks like it has been polished off by the rings and likely won't be a problem if the peaks of the rust are gone. Pitting won't hurt anything either as long as the rings were not worn to the pint of being a problem. Which is unlikely if your oil consumption is stable and not excessive.
Good Luck,
Mahlon
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My first guess is rust also, as it is just too orange to be glazing and can't imagine what else it could be. Pits tend to be black in color in my experience and have never really seen orange on cyl walls. Cross hatch angles seem pretty shallow to me also.
 
prkaye said:
I can't see how it could possibly be rust... these were freshly reconditioned cylinders installed by Aerosport Power about a month ago!
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when they installed them is not the question, but rather WHEN they were reconditioned and how long they sat before installation, as well as whether or not the shop put oil on them after honing. Would like to think that aerosport would not install cylinders with corrossion, but you never know.
 
I wonder if the tint could be the oil? I scoped it within a couple of hours after a flight. The oil on the dipstick was brownish when I did the oil change and borescoping... Might a film of brownish oil on the cylinder wall reflect the light from the scope and appear that way?
 
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prkaye said:
I wonder if the tint could be the oil? I scoped it within a couple of hours after a flight. The oil on the dipstick was brownish when I did the oil change and borescoping... Might a film of brownish oil on the cylinder wall reflect the light from the scope and appear that way?
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I have borescoped at least 20 different engines and have never seen orange. Each of those engines used oil for lubrication. I also use the VA-400. Not saying it is bad, as I am still uncertain what it is, but it is not liquid oil you are seeing. WHile a glob of oil on a dipstick may look brown, it will NOT look brown when it is an .001" coating on a cyl wall.
 
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I personally think you are seeing reflection off of the deposits on the cylinder crown. Good idea to ask Aerosport though. They are good about responding.
 
I personally think you are seeing reflection off of the deposits on the cylinder crown.
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Aerosport just got back to me and that's exactly what they think. Here's what they said:
It looks to me that you’re seeing the reflection of the top of the piston on the cylinder walls. Borescope pictures can be deceiving when you don’t have anything to compare to. Try shining a flashlight in a spark plug hole and seeing inside with just your eye to see what your borescope is ‘seeing’ so you get a better visual comparison.

If you compare the cylinder walls to the top of the piston as a mirror image you’ll notice the colouring and markings look very similar. This is very evident when you compare the images of the cyl. wall and piston top on cyl1 pic3, cyl2 pic1, cyl3 pic1, and cyl4 pic1. The cylinder walls may be shiny and cross-hatched, but are acting like a mirror so they look brown.
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Lighting

Looks to me like the camera lighting. Same color on your valves and pistons , both would be either black or light in color depending on your LOP or ROP setting in cruise. No oil usage is a good thing.
 
Well, I learned my lesson about diagnosing via pics. Phil, the key with borescopes is learning to adjust the lighting output as well as constant movement, using different angles when viewing an area of the cyl. These cameras have a few issues and the dark environment can create all sorts of illusions. Generally it is pretty easy to get valve looks, but the cyl walls are a real challenge with the lower quality scopes.
 
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ARG, now Aerosport is telling me i may have glazed the cylinders. After those previous pictures I changed the oil and flew for an additional 12 hours. THen i changed the oil again yestereday and looked in cylinder#1 with a flashlight as was suggested. The yellow/tan colour was still very visible, but it did shift and change when i moved the light in a way that is suggestive of reflections. I sent them this picture of the piston (i was wondering about those two raised bits that i have another thread about):
https://postimg.cc/PLW3KZXn
Aerosport said the wet appearance suggests oil getting past the rings, even though my oil consumption is good.
Oil consumption seems to be 12hrs/qt or better. Compression test 76/80 all cylinders (taken with engine cool). Lower plugs are dry but very black and sooty. I ran for rich on 100LL at high power (over 75%) for the first few hours. After 10 hours switched to mogas and started leaning. Last few hours running LoP. CHT's all in the 320-350 range.
I was very, very careful to do break-in properly, and as others here have said the rings were likely seated in the 2-hour run in the test cell anyway. CHTs never got above 400F during break-in.
If this oily appearance is indeed evidence of glazing, what are the long-term consequences of that? Is it likely to lead to engine problems down the road? Is oil consumption the only concern wrt glazing? So far oil consumption seems fine and the engine is running well.
I'm thinking about signing-up for Savvy Q&A, but i've already thrown so much money at this engine in the last 7 months :(
 
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