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Borescope Video - Should I replace this cylinder?

moespeeds

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Cylinder #1 in my Mattituck Lycoming IO-360, 400 hrs since new, built in 2009

Symptoms were low compression (low 60s, came up to 74 after staking the exhaust valve). I get very dirty oil within a few hours. Oil burn is a quart every 3-5 hours.

You can see a scuff on the cylinder wall, Savvy says it looks like it had a stuck wrist pin. There's also the wide dark vertical lines, evenly spaced that I can't identify, but they are not showing in any of the other cylinders.

Video - Cyl #1: https://youtu.be/282Tuh9oENc

Here's a video of cyl #2 for comparison. 3 & 4 look the same as 2. Compression was 78 on all 3.

Video - Cyl #2: https://youtu.be/4nLdtXPAEI8

Savvy recommends just monitoring it, but they always advise not removing the cylinder. I have zero issues buying a new cylinder, if that's what this needs. Engine seems to run just fine other than the dirty oil.
 
"dirty" oil

I read about dirty oil a lot. Does a parameter in an oil analysis better quantify this? (lead ppm ?)
 
I find it weird that the mark on the cylinder wall is perpendicular to the stroke of the piston. If the wrist pin was stuck it would have marked the cylinder wall in the direction of the stroke of the piston. So I’m my opinion I don’t think it was a stuck pin. I say don’t replace it and monitor it. You might use/burn a tad more oil but other than that why replace it
 
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400 hrs since new, built in 2009

which equates to about 30+ hours a year, so the engine ain't overworked.
There is a slight piston pin sliding mark, but it does not seem deep enough to worry about, the more so if your oil analysis is ok.

The quick blackening of your oil, and your consumption eventually point to stuck rings, so a flush could be done on this cylinder, there's been a few threads on the subject here before.

Buying a cylinder kit is one thing, installing it another :)
 
Where do you have the leak?

Hi

I have nearly the same engine, the same age, same hours.

It would be interesting, where you have the compression leak?

Noise in the exhaust? Noise in the Intake? Noise in the engine case breather? During the compression check?

The valve stacking has nothing to do with the scuffing or white marks.
Oil burn has nothing to do with the valve ... more with the rings.
Black oil tends to be also more likely rings ...

If it is the exhaust valve, grind it and replace the rotator cap. Make sure that this valve is rotating! Otherwise, it will bend, and deform due to the asymmetrical thermal load ... and then grinding it in won't help anymore.

The rest looks normal to me ... may be a small patch of glazing.
 
Moe, the only thing I see that seems unusual is on #1 at 34-37 sec into the video. I can not tell the clocking relative to crank centerline, but it appears to be at 90 deg. It is an irregular, but somewhat elliptical spot with a whitish haze over the top. It sure appears to be abnormal and possible bore distortion. Being low in the cylinder it could well be a sticky wrist pin. It is certainly a piston to wall abnormality. If it is a wrist pin suck and not doing its job, then it could lead to a serious issue.

I have some of the vertical scratches in my barrels that don't have excessive oil usage. Most cross hatch is as expected for the hours and nominal.

If a better resolution and confirmation of the spot clocking could be posted, it could be quite helpful. W/O better visibility, a more detailed evaluation is beyond me.

#2 I did not see any abnormal (for an aircraft engine) appearance of the barrel.
 
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I would do the Savvy oil ring flush on all the cylinders and see if that improves the oil consumption. You could also lap the exhaust valve prior to the flush to clean it up.
 
Based on the condition of the head of the piston, the top dome of the cylinder and the lower spark plug, it would indicate that your oil consumption is not coming from that cylinder. All three areas appear to be dry and not wet with oil. The score mark in number one is not alarming.
If it were me, I would fly the aircraft and recheck the compression. If ok back to routine maintenance. If low again based on the fact that the reading recovered after staking the exhaust valve, on the original leak down, it would indicate that the leak was actually from the exhaust valve to seat interface. Listening at the exhaust, during the second compression test should confirm that. Although, a reading in the 60's isn't the end of the world, if leaking past the exhaust valve is repeated on the second test, it isn't likely to get better over time and will probably get worse. Lapping the valve to the seat, and checking guide wear, with the cylinder in place would be the way I would go.
As to the oil consumption, look for a cylinder that has a wet lower plug and that part of the piston head is wet or damp with oil. That would be the culprit. Does the oil consumption appear to be erratic? Averages 1 in 3 hours but sometimes better and sometimes worse? If so, that could be a worn piston skirt. When that happens the wet cylinder evidence can be hard to find as its there when it using a lot but not there when it isn't. Normally, if that condition exists, one cylinder will have way more deposit build up on the head and piston than the others and that would be the indicator that that cylinder has a work skirt and may be the one causing the higher oil consumption.
Good Luck,
Mahlon
 
I see glazing on the lower half of the walls (the orange stuff with your cameras color palette) and is not uncommon and very likely the cause of your high oil consumption. This excess consumption can also increase carbon debris on the valves and why you got the leaky exh valve that was cleared by knocking it off. Are any of the plugs wet with oil after idling. Looks like good cross hatch in the upper half. The light vertical lines are scuffing from loose clearance and seen on many Lyc cylinders and not a reason for concern. The darker lines could be a few different things, but agree with Savy that not worth pulling apart yet. Could also be a stuck ring.

Larry
 
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Thank you for all the responses.

The scuff is in line with the wrist pin, around 3 o'clock if 12 is up.

I did do a ring wash on all cylinders, as per savvy. #2 seemed the most difficult, as it kept coming out of the exhaust valve, but eventually I got them all to flow through the rings.

I get an oil analysis every oil change, 3 so far for this plane. All 3 showed elevated nickel and iron. One showed elevated aluminum as well.

My cylinders have a grey/silver stripe, so according to Lycoming that indicates a steel cylinder?

Anyone have any input on what those dark stripes are running symmetrically around the cylinder wall? None of the other cylinders have this.

For those interested, heres cyl #3: https://youtu.be/S6WhajV3iiY and cyl #4: https://youtu.be/z0Yvc81GljE
 
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T

Anyone have any input on what those dark stripes are running symmetrically around the cylinder wall? None of the other cylinders have this.

l]

As I mentioned above, that is glazing and is caused by getting the cylinder too hot during break in.
 
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The cylinder markings I saw in the video would indicate nickel carbide IFR treated heads. I saw teal blue with a silver stripe down the middle.
Good Luck,
Mahlon
 
The cylinder markings I saw in the video would indicate nickel carbide IFR treated heads. I saw teal blue with a silver stripe down the middle.
Good Luck,
Mahlon

The whole case is painted gold, but there is a barely discernable silver or grey stripe on the fins where cylinder colors are typically marked. The camera distorts the color, it's actually gold with a silver/grey stripe.
 

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Moe - I have similar engine (Mattituck Lycoming IO-360 180 HP), with slightly fewer hours. I had low compression on #2 cylinder. Bore scoping did not show oil streaking or other abnormalities, so we assumed carbon on exhaust valve as we could hear air during compression test. Valve lapping did not help, so I sent the cylinder to Johnson Aircraft Services in Tulare, CA. They found and replaced two broken rings (oil and one compression), dressed exhaust valve and seat, and honed cylinder.
 
Good link, working ;)
 

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So this would be 2 silver stripes, Ni plated? Would make sense since we had nickel in the oil analysis.
 
cerminil

Not sure if it's related, but I had ECI Cerminil cylinders with about 460 hours on them over a period of just over 12 years, so very similar in age and usage to the engine in the OP (mine is an O-320). Last Sept I had a broken piston ring. I ended up with a large amount of almuminum through the engine and had pulled it for a very expensive IRAN. Oil analysis showed the severly elevated aluminum, and also elevated nickel.
To the OP - might be worth verifying if your cylinders are Cerminil, and maybe verifying that they weren't affected by that big AD that came out for a bunch of them about 10-12 years ago. I replaced all four of those ECI cylinders with Superior steel cylinders with the IRAN this winter.
 
ECI nickel carbide cylinders had a 2006 Service Bulletin about delaminating top compression rings. One symptom is the oil turning black quickly however the SB likely does not apply to you as your engine was built in 2009???

Fin 9A
 

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