Top End Overhaul - Questions

[irishpilot]

Well, my M20e needs a top end rebuild and I've done some searching and it looks like I can refurbish my cylinders (if they are in good enough condition) or I can buy new. From what I read, if I go new I only have the choice of Lycoming. Is this true? It is for an IO-360A1A. If so, where are the best prices and any lesson learned? Thanks for the help.

[N601RX]

Lycoming is the only option new. They are around $2k each. Because of the price difference between new and repaired most people choose to repair their existing cylinders as opposed to new or exchanged cylinders of unknown origin. 

What is wrong with them? Compression, oil usage, valve leakage?

[slowflyin]

I've done both new and used.   As 601RX noted, Lycoming is the only option of new and I use Gibson Aviation for used.    My preference for the A1A is new.

[KSMooniac]

My preference, depending on the total time and the malady, is to repair what you have if total time is less than 4000 hours and they measure within spec.  You can also choose a good engine shop that can do some extra work such as flow-matching the cylinders together, which will result in a smoother running engine.  You can also balance the pistons more precisely than what Lycoming will typically provide off the shelf.  

I'd be very wary of buying a random, used cylinder, though, unless you knew the history and measurements.

[N601RX]

Look through your logs and see how many hours are on them since they were new.  Then see if they are oversized or std.  Also determine if they are chrome or steel. How many hrs on the motor since overhaul?  What is the general condition of the rest of the engine? Assuming the engine has somewhere in the 1000hr range then repairing the cylinders should last you as long as the rest of the engine.

[Yetti]

do they all need to be done?  Probably just #3 to start with.   Buy one new, then rotate around fixing the worst one or two at a time.

[irishpilot]

The engine was last overhauled in 1973, and it has 1170 hrs. Not much flying which is what caused the the higher iron reading. I won't buy used. I hope they can be overhauled. The Lycoming ones are $2300 a piece.

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[Yetti]

A year ago I got a new one from Air Power for right at 2 AMU

[N601RX]

I would not remove them based on just a high iron reading.   As long as compression, oil consumption and borscope looks good continue to fly and monitor it. The high iron could also be coming from the cam. 

[cliffy]

More information is needed for the best advice here.

Who is telling you you need cylinders?

What are the compression readings?

Have you borescoped the cylinder walls yet?

Are they original to the engine since new?

How many hours TT on each cylinder?

Have any of them been worked on since new?

Are you basing everything on one oil analysis? 

How many oil analysis' have you done?

Are the trends showing a change?

Is the engine giving you any other trouble or symptoms of trouble?

 

[irishpilot]

Sorry, here is the full story. I fly 5 hrs per week and the engine started running rough. Oil consumption jumped to 1 qt per hr and if ended up fouling two plugs. We pulled the lower plugs and found lots of oil pooled. We cut the oil filter and found lots of ring debris. Compression went from 72 three months ago to 58.

The logs show an overhaul in 1973 but nothing since. We can't find anything newer other than the standard annuals. I have to assume they haven't seen any work since.

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[irishpilot]

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[kpaul]

9 years between oil tests?

Edited February 6, 2016 by kpaul

[glafaille]

42 years since the last overhaul is a very long time.  Lycoming recommends 12 years between overhauls and although just a suggestion, you are several times past that.  Might be time to bit the bullet.

[C-GHIJ]

12 years between overhauls.....REALLY.  The average pilot fly's less than 100 hours a year.  It wouldn't be mid timed by the time they recommend an overhaul.   Personally I wouldn't touch a perfectly running engine regardless of the TBO. 

[Shadrach]

Irish, 

Our A1A went 37 yrs and 1800 without an OH. Can you tell us if these Cylinders we're new at last OH. My opinion is that Lyc Cylinders are good for 1 OH (4-5000hrs TT in service). what are the comps on the other 3cyl? The thing is, that engine owes you nothing. I am concerned that you may be throwing good money after bad. You'll know more when you pull the jug. If they're low time jugs, you might get all of them R&R'd and OH'd for about 5K. New will be closer to 10k. You could just do the soft cyl for about $1500. Are you flying a lot of hard IFR?

Edited February 10, 2016 by Shadrach

[irishpilot]

The log entry states nothing specific. We will know more when we pull the jugs on Monday. We will run them up to the engine shop and see if they can be overhauled.

I do fly IFR and the family, so just doing one cylinder is out. It's either new cylinders or overhauled. That's if we don't find anything wrong with the bottom end.

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[cliffy]

  A lot can be learned with a good knowledgeable borescope of the cylinders. 

What do you mean by "ring debris"?  large chunks of broken rings?

Again, were the cylinders original from new engine or replaced at overhaul. ?

If original, were they overhauled at the engine overhaul in 73? 

What are the cylinder total times?

I'm not a big fan of second overhaul on jugs, You might consider all new jugs then if the bottom end gives you problems down the line (like at 500 more hrs)

you could get away with a good inspection and re-ring with time continuing on the cylinders and do a bottom end repair. It wouldn't count as a full overhaul but in essence that is what you would have. I did that once after a new cylinder top and 100 hrs later a bolt worked loose on an idler gear in the rear case, The airplane is still going strong 1100 hrs later. 

 

 

 

[Shadrach]

5 hours ago, cliffy said:

  A lot can be learned with a good knowledgeable borescope of the cylinders. 

What do you mean by "ring debris"?  large chunks of broken rings?

Again, were the cylinders original from new engine or replaced at overhaul. ?

If original, were they overhauled at the engine overhaul in 73? 

What are the cylinder total times?

I'm not a big fan of second overhaul on jugs, You might consider all new jugs then if the bottom end gives you problems down the line (like at 500 more hrs)

you could get away with a good inspection and re-ring with time continuing on the cylinders and do a bottom end repair. It wouldn't count as a full overhaul but in essence that is what you would have. I did that once after a new cylinder top and 100 hrs later a bolt worked loose on an idler gear in the rear case, The airplane is still going strong 1100 hrs later. 

I'm curious, why would you bother re-ringing 500hr cylinders?

[ArtVandelay]

Why is just doing 1 cylinder out? Are you doing the others as preventive maintenance?

[glafaille]

One of the problems is that cylinders are not serialized to my knowledge and therefore difficult to track. If the aircraft was built prior to 1973, the odds are they were overhauled in 1973.  Few owners are willjng to write the check for new cylinders on these engines unless they have to.  Therefore I'm betting this will be overhaul # 2 on the cylinders.

One consideration; As a buyer a "Top Overhaul" is meaningless to many and may not get you a higher offer than a "run out" engine.  A proper overhaul includes a lot of other stuff than just splitting the case and overhauling the cylinders.

Hard IFR, family on board, time of expected ownership, and re-sale value are the things that make this a hard decision.

[irishpilot]

Thanks for the insight. There is a lot to think about. As far as resale goes, I may have to bite the bullet and do an engine overhaul. It it tough since the engine has 850 "hours" left. I will post more once we get access to the internals next week.

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[Shadrach]

1 hour ago, teejayevans said:

Why is just doing 1 cylinder out? Are you doing the others as preventive maintenance?

I too am a fan of "on condition" MX but at 42 years and 11XX SMOH or TT (still waiting to find out which), I'd be inclined to pull them all.

[RLCarter]

Give these guys a call, J&J Air Parts. 

[irishpilot]

Shadrach, the log showed 480 hrs when it was overhauled. It makes no mention of specifics accomplished. I will assume that the cylinders were overhauled and not replaced. The engine currently has 1180. So the cylinders have 1180 SMOH and 1660 TT. Am I doing the math right?

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