Stuck Oil Ring

[FlyboyKC]

I believe I have a stuck oil ring, I seem to burn about 1 qt every 4 hours and the oil blackens very quickly, within 6 hours. I am not seeing any oil on the belly, however I don't seem to be able to lean as great as I should. When I pull the bottom plus all the plugs look pretty normal in that one is NOT oil soaked. Below is a picture of the engine monitor, not sure how to tell from the monitor which cylinder might be the offender.

I have tried all the normal remedies to get the ring unstuck, however it only frees for a bit and then seems to stick again. All the compressions are 70+/80psi and the engine runs strong, just burns the oil. I am not overly worried, but I would like to address it next annual if I can figure out which cylinder is having the issue.

Any suggestions would be welcomed.

Neal

 

b

[carusoam]

See if aligning the ring with gravity helps...   

Is the oil showing up in the exhaust pipe?

-a-

[RLCarter]

I would think if you had an oil control ring stuck you'd have an oily plug

[PT20J]

I bought a J a year ago. Engine ran fine, lowest compression was #4 72/80. Filter was clean, last oil analysis was OK, borescope inspection by Don Maxwell himself was OK. But... it was burning a quart every 2 hours. I flew it for about 30 hours, still running fine and put it in for annual. Compression #4 58/80, metal in the filter, part of an oil ring in the suction screen. Pulled #4, found the oil control ring broke and took out part of the piston skirt and scored the cylinder. Metal had contaminated the rod big end bearing so it must have gotten around the engine pretty well. Oh yeah, and the cam was spalled. 

Moral: probably not a good idea to continue running it if you think an oil ring is stuck, because if it breaks, it makes a mess. Better to pull the jug and have a look.

My bottom plugs were not very oily and there wasn’t a lot of black soot in the tailpipe and the belly was clean.

Skip

[DXB]

Engine monitor may not help much here.  The same bottom plug being oily all the time (not just once) is a pretty good clue.  Scope your exhaust valves, and your cylinder walls for scoring, while the bottom plugs are out.  Has it been stable at 4hrs for a while or taken a precipitous drop to that recently? 4hrs is acceptable but may force your hand sooner than at annual if it gets much worse, which it probably will.  At which time the offending cylinder may also become more obvious.  

[PTK]

9 hours ago, FlyboyKC said:

All the compressions are 70+/80psi and the engine runs strong, just burns the oil. 

Neal, do you keep a log of oil added by hours of operation? If so have you noticed a sudden increase in oil consumption rate? and are any top spark plugs oily? Also are your compression checks done hot or cold? I would do a good hot differential compression check. If you have one cylinder with a lower reading than the rest then I would borescope this cylinder. Sometimes pulling a cylinder is unavoidable but it’s helpful to narrow it down.

[ArtVandelay]

I would think if you had an oil control ring stuck you'd have an oily plug

But it may not be so bad as to be obvious. Especially if you run rich, the excess avgas will wash off the oil.
I would do a GAMI check and run the engine lean, borescope the cylinders and carefully checked the plugs against each other. I would also check the sump screen looking for metal.


Tom

[FlyboyKC]

The oil consumption varies, but I seem to suck a quart every 4 hours. Although I am starting to detect a fouling plug after the engine has sat a couple of days, which is a new development. So the next chance I get I am going to pull the bottom plugs and hopefully the culprit will be obvious.

[kortopates]

You can try the non-invasive ring wash first to unstick it. In doing so,   not only is not much more trouble to wash all 4 cylinders once you're set up to do it, but that's how you'll know if you do have a stuck/gummed up oil ring, you'll feel it when it unsticks. Ed Kollin of Camguard published a ring wash solvent recipe that has proved most popular and perhaps successful for the job. 

I didn't see the recipe here, but this BT thread describes the process.https://www.beechtalk.com/forums/viewtopic.php?f=37&t=143044&start=15

Edited July 22, 2019 by kortopates

[RobertGary1]

If you have to pull a jug its not the end of the world. Might even be a good idea if the engine has some time on it just to check things out.

 

-Robert