Suspected Broken Oil control ring

[Greg Ellis]

I have a C model with an O-360-A1D.  I am going through a lot of oil (4 quarts on a 3 hour flight for instance and landed with only 3 quarts on board).  Borescope showed a lot of oil in the #1 cylinder with both top and bottom spark plugs being wet.  The attached photo is just one of many showing the oil in the cylinder.  I have spoken to 3 A&P/IA's.  They suspect a broken oil control ring.  They all say the cylinder needs to come off.  I know that can be an invasive procedure and if it must be done then it must be done.  However, is there any way to see if it truly is a broken oil control ring or something else like a stuck ring or crud buildup causing the issue.  I am reaching on this not knowing exactly what to be looking for.  All mechanics say don't fly it but my regular mechanic at my airport is so backed up it has already been since August waiting for him to work on it.

Would the controversial Savvy Ring flush do anything for me?  Is it worth a try?

Thanks for any advice.

[Fly Boomer]

11 minutes ago, Greg Ellis said:

Would the controversial Savvy Ring flush do anything for me?  Is it worth a try?

Might be one of those "can't hurt; might help" deals.  Sounds like you may be way beyond a ring flush at this point, but if you can find someone who both knows how to do it, and has time to do it, it's certainly less invasive than pulling a cylinder.

[N201MKTurbo]

I agree that a ring flush is worth a try. Removing a cylinder is not as traumatic as you think. removing the intake and exhaust is the hardest part. 

[47U]

1 hour ago, Greg Ellis said:

Thanks for any advice.

Did the increase in oil consumption happen gradually, or was it a sudden onset?

Does the airplane have a history of being a hangar/ramp queen?  

How many tach hours/calendar time since the last major overhaul.

Do you have any oil analysis data?

[PT20J]

The ring flush shouldn’t be controversial and cannot hurt anything. I would give it a try. Maybe the ring is just stuck. I definitely wouldn’t fly it. I had an oil control ring break and it took out a chunk of piston skit, trashed the cylinder and ran metal all through the engine.

The good thing about removing a cylinder is that it gives you an opportunity to inspect the cam. Mike Busch is correct that removing a cylinder should be a last resort rather than a first reaction, but I think he’s made pilots overly fearful that it will cause your engine to come apart somewhere down the road. Aircraft engines are designed for cylinder replacement in the field and, done by the book, it is a routine procedure as @N201MKTurbo says.

Skip

[Greg Ellis]

1 minute ago, 47U said:

Did the increase in oil consumption happen gradually, or was it a sudden onset?

Does the airplane have a history of being a hangar/ramp queen?  

How many tach hours/calendar time since the last major overhaul.

Do you have any oil analysis data?

Oil analysis is done every oil change and I have attached the most recent report done right before the offending flight.  I usually fly over 100 hours a year however the plane has been down multiple times for avionics, autopilot, etc...  But it normally flies about 100-150 hours per year.  It is definitely not a hangar queen.  The current engine is about 1400 hours since overhaul but it has had cylinder work done on it over the last 4-5 years.  This particular cylinder was off at the annual (January) for an IRAN and exhaust valve replacement.  There was nothing mentioned about any other issues.

The increase in oil consumption started last year and was using about 1 quart every 4 hours or so compared to 1 quart every 12-14 hours previously.  This was within Lycoming specs so I was not concerned and just monitored it.  However, it made rapid leap on one 3 hour cross country.  I was about 5 minutes from landing and the oil pressure went from 64 or so which it usually runs down into the upper 50's.  The EDM 900 alarmed me.  I made the landing at my destination and had to add 4 quarts of oil to bring it up to 7 on the stick.  I flew home and actually the oil burn was better.  I made it back with 5 quarts and I have not flown it since from the advice of the A&P's.  

N6541U-230608.pdf

[EricJ]

+1 I think it's worth a shot at the ring flush.   There's very little risk in trying that.   If it doesn't work then pulling the cylinder isn't the end of the world.   

Just adding my 0.02 to the previous wisdom, which seems consistent.

[PT20J]

I purchased my airplane in 2018. The engine was burning about 2 hrs/qt. Don Maxwell did the pre-purchase inspection, which I personally witnessed. He reported minor pitting and some oil in the cylinders (he used an old style optical borescope that did not have a camera). Compressions were all in the 70's, the oil filter was clean and the last oil analysis done about 20 hours previous showed no unusual wear metals. Except for burning oil, the engine ran fine. About 40 hours later I put it in for annual inspection. Cylinder #4 had a compression of 58/80, there was metal in the filter and a piece of ring in the suction screen. 

So, engines can degrade slowly, or they can go bad pretty quickly.

Skip

[PT20J]

BTW, if you don't want to bother mixing up Mike's flush brew, my IA says he's had good success freeing up stuck rings with Marvel Mystery Oil. (MMO is mineral oil, Stoddard solvent, a little TCP and some dichlorbenzene (plus red dye and peppermint fragrance ) I'm not a chemist, but according to Wikipedia, dichlorbenzene softens and removes carbon from metal surfaces.

Marvel_Mystery_Oil.pdf

[Greg Ellis]

5 minutes ago, PT20J said:

BTW, if you don't want to bother mixing up Mike's flush brew, my IA says he's had good success freeing up stuck rings with Marvel Mystery Oil. (MMO is mineral oil, Stoddard solvent, a little TCP and some dichlorbenzene (plus red dye and peppermint fragrance ) I'm not a chemist, but according to Wikipedia, dichlorbenzene softens and removes carbon from metal surfaces.

Marvel_Mystery_Oil.pdf 429.89 kB · 0 downloads

I do have some of that in my hangar.  By the way, a conundrum, if I try the ring flush and it sounds like the flush is going into the sump then the instructions say the ring is clear but how do I still know that it is not a broken oil control ring letting the solvent go by?  I was told not to fly it so I can't tell if the oil burn issue is resolved either.

[N201MKTurbo]

13 minutes ago, Greg Ellis said:

  I was told not to fly it so I can't tell if the oil burn issue is resolved either.

Your A&P IA cannot ground an airplane that is still in annual. It is up to you weather it is airworthy to fly.

[PT20J]

10 minutes ago, Greg Ellis said:

I do have some of that in my hangar.  By the way, a conundrum, if I try the ring flush and it sounds like the flush is going into the sump then the instructions say the ring is clear but how do I still know that it is not a broken oil control ring letting the solvent go by?  I was told not to fly it so I can't tell if the oil burn issue is resolved either.

If I did the ring flush and thought it made a difference, I would then do an extensive run up including some full power runs and then borescope it again to see if there is oil in the cylinder. If not, then I'd fly it a couple of hours orbiting the airport at perhaps 3000' AGL (I did this when I put on the new engine) and land and check oil level and borescope the cylinder again.

[Greg Ellis]

28 minutes ago, N201MKTurbo said:

Your A&P IA cannot ground an airplane that is still in annual. It is up to you weather it is airworthy to fly.

The airplane is not in annual.  It is just their advice to not fly it.

[Greg Ellis]

28 minutes ago, PT20J said:

If I did the ring flush and thought it made a difference, I would then do an extensive run up including some full power runs and then borescope it again to see if there is oil in the cylinder. If not, then I'd fly it a couple of hours orbiting the airport at perhaps 3000' AGL (I did this when I put on the new engine) and land and check oil level and borescope the cylinder again.

Thanks.  I believe this is what I will try this weekend then go from there.

[Greg Ellis]

Thanks to everyone who have responded.  I appreciate all of the advice.

[Andy95W]

24 minutes ago, Greg Ellis said:

The airplane is not in annual.  It is just their advice to not fly it.

When Rich said “in annual”, that means that there is a current annual inspection within the past 12 calendar months.  If the aircraft is “out of annual” it is not legal to fly.

[Greg Ellis]

3 minutes ago, Andy95W said:

When Rich said “in annual”, that means that there is a current annual inspection within the past 12 calendar months.  If the aircraft is “out of annual” it is not legal to fly.

Thanks.  I misunderstood.  Thanks for the clarification.

[M20F]

You cannot check the oil ring without pulling the jug.  What is the compression?

I have been working on a similar issue with my #2.  1 quart an hour, normal CHT, EGT, compression, etc. pulled the cylinder and the oil ring is fine.  Advice from some was oil ring others was 1 quart with good compression is too much for blow by with good compression.  
 
No visible cracks or other issues.  Waiting to see what the machine shop says.  Guessing valve guide.  I love airplanes…..

[Greg Ellis]

6 minutes ago, M20F said:

You cannot check the oil ring without pulling the jug.  What is the compression?

I have been working on a similar issue with my #2.  1 quart an hour, normal CHT, EGT, compression, etc. pulled the cylinder and the oil ring is fine.  Advice from some was oil ring others was 1 quart with good compression is too much for blow by with good compression.  
 
No visible cracks or other issues.  Waiting to see what the machine shop says.  Guessing valve guide.  I love airplanes…..

Compression on that cylinder is 68/80 cold so I suspect it would be much better when hot.  All other things are in the normal range including CHT's, EGT's etc...

[Greg Ellis]

7 minutes ago, M20F said:

You cannot check the oil ring without pulling the jug.  What is the compression?

I have been working on a similar issue with my #2.  1 quart an hour, normal CHT, EGT, compression, etc. pulled the cylinder and the oil ring is fine.  Advice from some was oil ring others was 1 quart with good compression is too much for blow by with good compression.  
 
No visible cracks or other issues.  Waiting to see what the machine shop says.  Guessing valve guide.  I love airplanes…..

The cylinder just had the exhaust valve replaced.  I wonder if something went wrong there.

[PT20J]

48 minutes ago, Greg Ellis said:

The cylinder just had the exhaust valve replaced.  I wonder if something went wrong there.

When you do the compression test, remove the dipstick and listen for where the air is escaping. If it is hissing out the dipstick tube, it's getting past the rings. If it is hissing out the tailpipe, it is getting past the valve (rarely it may hiss out the air filter due to a problem with the intake valve).

An oily cylinder with bad rings can have good compression because the oil seals the rings. (It was an old diagnostic trick on autos to squirt some oil into a cylinder with low compression and see if it improved to isolate a ring from a valve problem). 

A lot of times you can fool around rocking the prop back and forth (stand well clear - if you move it too far it will spin on you) and significantly change the compression readings as the rings move back and forth in the grooves. There is actually quite a bit of play there.

Skip

[BDPetersen]

Your picture and consumption scenario look identical to mine, although I had 78/80 compression. #4 cylinder. Pulled the cylinder under the advisement of a reputable overhauler. Top ring was broken. Now waiting for cylinder to come back from shop. Hopefully worth it. No scoring, clean oil filter, slightly elevated chrome in oil analysis but no higher than earlier tests. We’ll see.

[47U]

4 hours ago, Greg Ellis said:

The cylinder just had the exhaust valve replaced.  I wonder if something went wrong there.

From looking at the amount of cross hatch, does it appear that when the exhaust valve was replaced they didn’t hone the cylinder and would then have reused the rings?

Perhaps something did go wrong there…

[Bolter]

6 hours ago, M20F said:

You cannot check the oil ring without pulling the jug.  What is the compression?

I have been working on a similar issue with my #2.  1 quart an hour, normal CHT, EGT, compression, etc. pulled the cylinder and the oil ring is fine.  Advice from some was oil ring others was 1 quart with good compression is too much for blow by with good compression.  
 
No visible cracks or other issues.  Waiting to see what the machine shop says.  Guessing valve guide.  I love airplanes…..

I had great compressions, and similar between each cylinder, but still found a broken oil ring on one cylinder that was the source for 1qt/hr level oil consumption.  Borescope, compression, and cylinder wash.  None helped identify the root cause or which cylinder to check first.  Of course, found the broken oil ring on the last cylinder to be removed...

(edit: this was on a J with IO-360, not my current plane)

-dan

[Pinecone]

I had my oil consumption jump up.  My FBO looked things over and then removed and flushed the crankcase breather line and the oil/air separator.

Oil consumption went back to normal.