To overhaul or not, that is the question...

[Oldguy]

August of 2003, my J had a Lyc. reman put in with a zero timed log. In March of 2006, after 466 hours, it had to be torn down to correct a bearing issue caught by oil analysis.

So 2 years and 7 months (past 2 year warranty) and with that many hours, would this be considered infant mortality? I would not think so, but to me it just shows anything can happen at any time regardless of the engine.

Now, with another 1400 hours or so after G & N rebuilt it, it is still going strong will hopefully make it to TBO and beyond.

[jaylw314]

1 hour ago, Oldguy said:

August of 2003, my J had a Lyc. reman put in with a zero timed log. In March of 2006, after 466 hours, it had to be torn down to correct a bearing issue caught by oil analysis.

So 2 years and 7 months (past 2 year warranty) and with that many hours, would this be considered infant mortality? I would not think so, but to me it just shows anything can happen at any time regardless of the engine.

Now, with another 1400 hours or so after G & N rebuilt it, it is still going strong will hopefully make it to TBO and beyond.

Well, if we played semantics, any bottom end failure prior to TBO is infant mortality, since TBO is supposed to have some meaning as the expected time-limited life of the components.  Presumably, your bearing issue was a manufacturing or assembly issue, since it should have lasted to TBO.

Granted I suppose abuse, misoperation or errors in maintenance could be other causes, but otherwise it would have to be a production, manufacturing or assembly issue.

[Raptor05121]

https://www.youtube.com/watch?v=v3mkB-cefZE

[ArtVandelay]

7 minutes ago, Raptor05121 said:

https://www.youtube.com/watch?v=v3mkB-cefZE

When posting links you might want to give a short summary of what’s about.

[Raptor05121]

Thought it would embed it. Its a quick overview on how the 2,000hr TBO isn't set because of parts failure, but rather the manufacturer's ability to lower the probability of failure by rebuilding engines with good components and the parts with errors can "die out" with each successful generation.

[MIm20c]

1 minute ago, Raptor05121 said:

Thought it would embed it. Its a quick overview on how the 2,000hr TBO isn't set because of parts failure, but rather the manufacturer's ability to lower the probability of failure by rebuilding engines with good components and the parts with errors can "die out" with each successful generation.

I agree that errors and worn out parts can be checked over carefully and replace only what is necessary to make the engine “new” again.  I’m of the opinion that 4-5 thousand cold (read not at operating temp) starts and sitting around for 50 years does not make a like new error free engine. 

I would feel a lot more comfortable behind a 4K hr recent quality overhaul that has been in continuous use by a flight school vs a 2500 hr original 50 year old engine. 

[Raptor05121]

Did you watch the video? It explains exactly that. The old stuff is junked, the new stuff is kept.

[salty]

The engine looks to be in pretty good shape overall. Interestingly, the top end has been overhauled, but it has some pretty major issues. 3 of the 4 cylinders have broken rings, in one case it's a real mess. The valves don't look to be bad. I haven't removed the rocker covers yet to see how it looks, I will likely buy new cylinders now that I see the situation.

[salty]

Here's the bulk of the bad news. Piston #4 is *insert horrible description of your choice here*. My mechanic is guessing maybe somebody put chrome rings in a chrome cylinder. Intake follower for cylinders 1 and 2 share the lobe in the second picture that is badly worn, the other followers and lobes were in good shape, but this one leaves much to be desired.

Most everything else is in pretty good shape considering the age.

Edited November 14, 2017 by salty

[salty]

rods and all crank bearings look good to the naked eye. 

[gsxrpilot]

Great pictures, thanks!!

[salty]

One thing is for sure, I have zero regrets about pulling the engine. I'm a little spooked out about what I was flying behind.

[bonal]

Looks like you made a good call did not notice if you posted but what were the compressions especially on number 4. Surprised there wasn't any abnormal amounts of material in your oil sample which makes me wonder the real value there. Excellent pictures and follow up report. I would not be spooked by having flown behind that engine it obviously got you there without failure and your spider senses said it was time to pull it. Do you know what approach your going to make for the replacement an OH or a re manufactured are the big pieces within tolerance 

[MIm20c]

16 minutes ago, salty said:

One thing is for sure, I have zero regrets about pulling the engine. I'm a little spooked out about what I was flying behind.

I’m glad you pulled the issue free engine because of the hrs and age. I still firmly believe that running an engine well past TBO is a great idea if you or someone you trust is maintaining and flying the plane. 

[salty]

Just now, bonal said:

Looks like you made a good call did not notice if you posted but what were the compressions especially on number 4. Surprised there wasn't any abnormal amounts of material in your oil sample which makes me wonder the real value there. Excellent pictures and follow up report. I would not be spooked by having flown behind that engine it obviously got you there without failure and your spider senses said it was time to pull it. Do you know what approach your going to make for the replacement an OH or a re manufactured are the big pieces within tolerance 

Next steps are to send out the crank and case and see how they are. I will also be sending out the carb and oil cooler. Haven't decided on mags yet. As I said, I'll probably buy new cylinders unless costs go too high on other things.

[salty]

compressions were all > 70 at last years annual. I regret not having tested compression before I pulled the engine. Would have been nice to know if it would have detected the broken rings. 

[RLCarter]

23 minutes ago, salty said:

compressions were all > 70 at last years annual. I regret not having tested compression before I pulled the engine. Would have been nice to know if it would have detected the broken rings. 

That ring looks to have been broken for a long time

[salty]

Yeah, I put 140 hours on it since the last annual. That damage is probably even older than that. 

[EricJ]

1 hour ago, salty said:

Yeah, I put 140 hours on it since the last annual. That damage is probably even older than that. 

Were you getting much blow-by?   Was there crap on the belly behind the breather or did the oil turn black very quickly after a change?

[salty]

It wasn't getting any worse since I bought a year and a half ago. I was getting a little out of the breather after a flight, nothing that set off an alarm. Exhaust has always blown more than it should probably in retrospect. 

[MIm20c]

On 11/12/2017 at 4:14 PM, salty said:

Next steps are to send out the crank and case and see how they are. I will also be sending out the carb and oil cooler. Haven't decided on mags yet. As I said, I'll probably buy new cylinders unless costs go too high on other things.

Do you need to overhaul the mags to call this an overhaul vs iran?

[salty]

I will be overhauling the mags or doing something with them, I'm just not sure how yet. 

[salty]

So, 10 months later, she’s back in the air. New: cylinders, camshaft, oil pump, fuel pump, oil cooler, prop hub (with no AD), jpi edm-900, engine controls. overhauled: prop governor, mags, prop blades, crankshaft, case, conn rods, carb. 

Im getting at least 10 mph more than before. Got 176 TAS at 80% power on the last flight.

So happy i did I myself. Took a lot longer, but I know every nut and bolt of the power plant now. Literally. 

Edited September 20, 2018 by salty

[Hank]

Congratulations!! That's a serious accomplishment!

[salty]

Thanks. It’s so nice to be flying a mooney again.