Cracked ring on #4 cylinder

[mschmuff]

Not the way I wanted this trip to go!

Made it to Florida from DC via Charleston and Saint Simons no problem but the last leg of the trip burned 1qt to 1 hour!  Had Rick at East Coast Aviation Services take a look at the plane at Stuart Airport.  Pulled the bottom plugs and #2 & #4 were wet.  4 was worse than 2 but we pulled them both.  Broken ring on #4.  Sent both to Certified Engines in Hollywood FL.  Waiting to hear if they can be IRAN'd or needs replaced.  Will give reviews of both shops once I'm back in the air.

Question for all the experts on here.  In the last 6 months I have been alternating for the first time between ROP and LOP. I always ran ROP before but with everything I have been reading thought I'd try LOP.  Note: I never take off until cylinders are over 200 degrees, always preheat, oil over 100, hottest cylinder(#2) never exceeds 370 on climbout and 350 in cruise. On descent, 2 inches of MP every 3-4 minutes and always monitor the CLD temp on my JPI.  Plane has never sat more than 13 days on these cylinders!  Could the LOP cause my broken ring??? Or was it just coincidental? 500 hours on all cylinders...

As always thanks for your help!!!

[Yetti]

#4 is a known problem child.

[Oldguy]

Your flight profile sounds almost exactly like mine with the exception I almost never fly ROP unless there is a significant headwind I am fighting or I just want the extra 4-5 knots. My current cylinders have ~1,600 hours on them and are running fine at this point. I am not an A/P and did not sleep in a Holiday Inn Express, but I would be surprised if running LOP could cause an issue like this.

[N201MKTurbo]

Hard to imagine what LOP would do to rings. S#!^ happens. If the cylinders are not scored, I would just get new pistons and rings, re-hone the cylinders and be done with it.

[mschmuff]

Just heard from Certified Engines that my cylinders are beyond repair.  Any idea what cylinders to replace the ones I had? New Lycoming? Superior? Overhauled ones?

[jetdriven]

New Lycoming Cylinders. Measure the ring gap carefully. Reassemble carefully. 

[Guest]

6 hours ago, mschmuff said:

Just heard from Certified Engines that my cylinders are beyond repair.  Any idea what cylinders to replace the ones I had? New Lycoming? Superior? Overhauled ones?

Depends, how many hours on the engine?

Clarence

[ArtVandelay]

Depends, how many hours on the engine?

He said 500 hours on all cylinders, so I would assume 500 hours.



Tom

[Shadrach]

9 hours ago, mschmuff said:

Just heard from Certified Engines that my cylinders are beyond repair.  Any idea what cylinders to replace the ones I had? New Lycoming? Superior? Overhauled ones?

If the engine is passed mid time, I consider overhauled with the plan of replacing when the engine is overhauled. If it has less that 1000hrs, I’d go new Lycoming. The price delta is about $1000-1200 per cylinder between new and overhauled.

[N201MKTurbo]

9 hours ago, mschmuff said:

Just heard from Certified Engines that my cylinders are beyond repair.  Any idea what cylinders to replace the ones I had? New Lycoming? Superior? Overhauled ones?

Why are they beyond repair? 

[PT20J]

10 hours ago, Yetti said:

#4 is a known problem child.

Tell me more...

[Guest]

30 minutes ago, ArtVandelay said:

He said 500 hours on all cylinders, so I would assume 500 hours.



Tom

Might be 500 hour cylinders on a 1500 hour engine, or 500 hours on a 500 hour engine.  It would make a difference to recommendations.

Clarence

[Shadrach]

11 hours ago, Yetti said:

#4 is a known problem child.

Never had an issue with #4. #3 is typically hottest on most F models but it’s not a problem.

[M20F]

50 minutes ago, M20Doc said:

Might be 500 hour cylinders on a 1500 hour engine, or 500 hours on a 500 hour engine.  It would make a difference to recommendations.

Clarence

From a resell perspective maybe, from any other perspective no difference. 

[bill98]

42 minutes ago, Shadrach said:

Never had an issue with #4. #3 is typically hottest on most F models but it’s not a problem.

#3 is always warmest on my M20E. 

#1 being the coolest. 2 and 4 always run around the same exact temp gicenor take 3-5 degrees F

[Shadrach]

2 hours ago, M20F said:

From a resell perspective maybe, from any other perspective no difference. 

Disagree. Overhaul with unknown history has a much lower likelyhood of lasting the remainder of a low time engine’s life.

[ArtVandelay]

Might be 500 hour cylinders on a 1500 hour engine, or 500 hours on a 500 hour engine.  It would make a difference to recommendations.
Clarence

If it’s the former, I would trade it in on a factory reman because that engine has serious issues.


Tom

[Shadrach]

16 minutes ago, ArtVandelay said:

If it’s the former, I would trade it in on a factory reman because that engine has serious issues.

 

Why would a factory reman be a solution to cylinder infant mortality?

Edited February 19, 2019 by Shadrach

[Yetti]

6 hours ago, PT20J said:

Tell me more...

When we got the plane #4 had a sticky exhaust valve.  So we reamed it.  Now it's the one that has oil issues.  I believe it's got same cooling issue like #3

[Shadrach]

1 minute ago, Yetti said:

When we got the plane #4 had a sticky exhaust valve.  So we reamed it.  Now it's the one that has oil issues.  I believe it's got same cooling issue like #3

It does not. These pistons are not symmetrical. #4 is oriented 180° from #3. #3’s tendency to be hottest is due to the rear baffle seal abutting the non-finned side of the cylinders head. #4 does not have the problem because it’s revesed and the fin side abuts the rear baffle seal.

[Shadrach]

@mschmuff - I’m really sorry that you’re dealing with this but I am releived that we didn’t do one of the flight we discussed prior to the failure. Has anyone diagnosed that likely cause of the failure? Both preignition and detonation can cause ring failure, but both of those events would come with significant heat (CHT). 

[Guest]

This engine ran more than 1300 with a top compression ring missing on a chrome cylinder with no consumption issues.

Clarence

[Shadrach]

2 hours ago, M20Doc said:

This engine ran more than 1300 with a top compression ring missing on a chrome cylinder with no consumption issues.

Clarence

I would be interested in its compression check history. Obviously it passed many annual inspections but did it give readings in line with the other cylinders?  I’ve heard enough stories of engines being assembled with rings missing or incorrect rings but I’ve never actually seen it first (thankfully) or second hand.

Edited February 19, 2019 by Shadrach

[BKlott]

21 hours ago, mschmuff said:

Just heard from Certified Engines that my cylinders are beyond repair.  Any idea what cylinders to replace the ones I had? New Lycoming? Superior? Overhauled ones?

In my situation if I had two cylinders go bad, my engine would be in the shop for a major overhaul. Keep in mind, I am at 1,300+ hours since major which was done by a quality shop back in 1998. At a certain point it just makes more sense to get it done and done right.

I would go with new Lycoming cylinder assemblies. Overhauled cylinders may may have thousands of hours on some of their components. For me, the price differential just isn’t worth the risk.

Another thought occurred to me since posting the above. If all four existing cylinders were from the same source, overhauled units by the same entity, having two of them go “beyond repair” in 500 hours would leave me with serious doubts that the remaining two were “fine and dandy”.

Barring some unusual circumstances such as the baffles were missing on one side of the engine but not the other, for example, I would be questioning the condition of the other two cylinders as well.

Your question about LOP versus ROP operations is a good one. The best advice I’ve read on the subject was that unless you had very good, modern instrumentation, you should not attempt to run LOP. 

Edited February 19, 2019 by BKlott

[M20F]

7 hours ago, Shadrach said:

Disagree. Overhaul with unknown history has a much lower likelyhood of lasting the remainder of a low time engine’s life.

What is unknown?  You know you have an either new cylinder or an overhauled one depending on which you choose.  You potentially still have no idea about the core or the other 3 cylinders.