Time for new engine

[jetdriven]

On 7/11/2020 at 12:24 PM, bbakerco said:

Hello oh wise keepers of Mooney knowledge,

The time has come to replace the engine in my M20J 201. (IO-360-A3B6D).  It's my first time ever replacing an AC engine so excuse my ignorance.  I'll admit that I did not look through all 175 pages of topics so I'm sure that some answers to my questions are burred somewhere in this monster.  My budget is $30k without additional financing.  My options as I see them are:

1. Buy crate engine from someone like PennYan (other recomendations???) and have it swapped.  Pro: Quick turnaround on M20. Better resale value (although not planning on selling). Financing?   Con: $$$$

2. Have my A&P tear it all down, send out for machining, assembly, etc.  Pro: Lower cost? (but more labor). Con: Slower turnaround.

3. Buy a certified block and have it built up until ready to swap.  Pro: Lower cost? Quicker turnaround.  Con: Frankenmotor?

Is there a 4rd option?  Am I missing any Pros/Cons?  I fly about 15 hours a month so I don't really want to be without the plane for 3 months but if it saves me $5k or more then probably strongly consider.  Successes, Horrors, Regrets with any of the above?  Is my budget about right or too low for everything?

Thanks,

Bryan

I’ve got a 2005 factory roller motor, the top end is gone but the case crank and all that is there. Would make a good foundation for a roller motor build, and the Only way to get one other than the factory.  

[Herlihy Brother]

Are you  at tbo for hours or years? I'm at 3000 hours and 35 years. The new unofficial Lycoming  tbo is 2,800 hours. In agreement with the earlier posts, I was at lycon last month and Ken said, camshaft problems? What problems those were solved 20 years ago. News to me, old wives tales die hard. Lycon is the best place to overhaul, plan on three months there.

[jetdriven]

I wonder, since the cam problem was solved 20 years ago, why there are so many owners on here wirh spalled lifters and cams.  

[Shadrach]

On 7/13/2020 at 10:40 AM, EricJ said:

Rebuild (sometimes called reman?) is a different standard than an overhaul.   Rebuilds are built to new tolerances, overhauls are built to service/overhaul tolerances, which are looser.   A rebuild/reman gets reset to 0 time and has no previous logbook or maintenance history.   An overhaul does not, only 0 TSMOH, the Total Time still accumulates and the previous maintenance history still applies.   I think the engine in my airplane has something like 4000 hours on it.

Be careful, as "remanufacture" isn't really a regulatory term and may or may not mean "rebuilt".

AC 43-11 has useful related info on the terminology and specifics, but for the most part the difference in price may reflect the difference in standards of the build.

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_43-11_CHG-1.pdf

 

I don’t know of a single overhauler that builds engines to service limits.  I’m not familiar with the term “overhaul tolerances”. Could you elaborate on that?  An engine can be called overhauled with nothing more than disassembly, inspection and measurements as long as it meets service limits. However, I know of no one that would do something that futile...  Zero time Factory Rebuild/Reman has nothing to do with tolerances and everything to do with parts traceability. If a core engine has a serviceable crank it is is used in “zero time” rebuild/reman build...same with the cam. A Factory Reman/rebuilt “zero time” engine is a collection of parts that are anything but zero time. Sure sounds great from a marketing standpoint...certainly much better than offering a 3800hr cam that is being driven by a 5500hr crank enclosed 4500hr case...

[EricJ]

7 hours ago, Shadrach said:

I don’t know of a single overhauler that builds engines to service limits.  I’m not familiar with the term “overhaul tolerances”. Could you elaborate on that?  An engine can be called overhauled with nothing more than disassembly, inspection and measurements as long as it meets service limits. However, I know of no one that would do something that futile...  Zero time Factory Rebuild/Reman has nothing to do with tolerances and everything to do with parts traceability. If a core engine has a serviceable crank it is is used in “zero time” rebuild/reman build...same with the cam. A Factory Reman/rebuilt “zero time” engine is a collection of parts that are anything but zero time. Sure sounds great from a marketing standpoint...certainly much better than offering a 3800hr cam that is being driven by a 5500hr crank enclosed 4500hr case...

I did mean "service limits".    Overhaul manuals often specify both manufacturing and service limits.   As you state, an overhaul to service limits is a legal overhaul.

 

And back to the original point, which your arguments are supporting, the differences in prices of proposed overhauls is often explained by the differences in what you get and how it's done, even if they're all called "overhauled" or whatever when done.    The difference in test and measurement and equipment and fixturing between a proper facility and a random A&P somewhere can be huge, but an engine through either may be called "overhauled" when they're done.

Edit:  BTW, "Zero time Factory Rebuild/Reman has nothing to do with tolerances" is apparently not correct.   AC 43-11 says that a "rebuilt" engine conforms "to the same tolerances and limits as a new engine".

 

Edited July 17, 2020 by EricJ

[Shadrach]

7 hours ago, EricJ said:

I did mean "service limits".    Overhaul manuals often specify both manufacturing and service limits.   As you state, an overhaul to service limits is a legal overhaul.

 

And back to the original point, which your arguments are supporting, the differences in prices of proposed overhauls is often explained by the differences in what you get and how it's done, even if they're all called "overhauled" or whatever when done.    The difference in test and measurement and equipment and fixturing between a proper facility and a random A&P somewhere can be huge, but an engine through either may be called "overhauled" when they're done.

I get what you’re saying. But they often repeated comments about Factory limits aren’t really what’s at stake in my opinion.  As I said earlier I don’t know of any overhaul shop that reassembled engines with bearings at service limits or cranks or cams for that matter.  I don’t have a lot of experience in this area but the three aeroengines that I’ve been involved in tearing down had cranks that still measured as new after 1000s of hours. The parts were still sent out to for reconditioning. My take is that anything inside the case by almost any overhauler is going to be built to new limits. The Delta in price comes in when you start talking about accessories and cylinders. There’s also a big Delta for name recognition. Operations like Victor and Penn Yan trade on there name and do provide additional services. That may or may not translate into a better engine.

I do not know of any overhaul shops that are assembling overhauled engines to service limits. Do you?

[ArtVandelay]

I assume unless they clearly state otherwise the default overhaul is to service limits. Otherwise why would you not proudly advertise the quality is above the standard?


Tom

[ryoder]

A guy I know has so many service limit replacement parts pulled from overhauls he has done that he told me he could overhaul my O360 at a steep discount if he used those parts.  He did mention some parts that I should get new but he would replace non serviceable parts with used serviceable parts from someone else’s new parts overhaul.

 

[EricJ]

6 minutes ago, Shadrach said:

I do not know of any overhaul shops that are assembling overhauled engines to service limits. Do you?

Some say specifically that they overhaul to new tolerances, (e.g., AES (who is local to me), Jewell, and Western Skyways), but some others don't say.   I'd think it could sometimes add unnecessary cost to put a new part or exchange a part where an existing part that is well within service limits might otherwise fit, particularly if it's a crank or other expensive item that typically has low wear.

So I don't know but I certainly wouldn't assume.   It's tough to prove a negative. 

An awful lot of parts are required to be replaced with new in the overhaul manuals, so the number of places where the distinction could apply may be less than some think, too.

[Shadrach]

18 minutes ago, ArtVandelay said:

I assume unless they clearly state otherwise the default overhaul is to service limits. Otherwise why would you not proudly advertise the quality is above the standard?


Tom

I think your assumption is wrong. Why not  ask around and confirm?

[ArtVandelay]

I think your assumption is wrong. Why not  ask around and confirm?

I didn’t have to, plenty to choose from. Same reason I didn’t “call for price” when looking to buy.

[Hank]

1 hour ago, ArtVandelay said:

I assume unless they clearly state otherwise the default overhaul is to service limits. Otherwise why would you not proudly advertise the quality is above the standard?

It doesn't matter who assumes what, or what's advertised by whom. All that matters is what is written in the contract that you need a signed copy of before "dropping off your engine" for overhaul / rebuild / remanufacture / fixin' up . . . .

[ArtVandelay]

It doesn't matter who assumes what, or what's advertised by whom. All that matters is what is written in the contract that you need a signed copy of before "dropping off your engine" for overhaul / rebuild / remanufacture / fixin' up . . . .

More importantly, what the log entry says.

[Hank]

8 hours ago, ArtVandelay said:

More importantly, what the log entry says.

No, the work completed is determined by tbe written contract. If it's not in the contract, they don't have to do it, regardless of what you assume. "Sure, we can rebuild an engine to astronomical specs like we advertise. But that's not what this contract is written for. This contract is for minimum specs." And there you are, all of their fancy talk and advertising notwithstanding, you paid for and received a quickie overhaul and have no recourse, even though you assumed you were getting a top notch, better-than-factory rebuild.

The log entry is required to state the work done, and you should receive invoices to match that include part numbers. Don't assume you will, though--make sure you receive it. 

[bradp]

On 7/12/2020 at 3:52 PM, Ragsf15e said:

In my opinion, a minimal oil leak that’s been stable for a good long time is not reason to open the can of worms involved in any type of MOH.  I’m as anal as anyone out there, but clean it religiously and get use to it, then enjoy your engine for a couple hundred more hours until it actually needs OH.  Just my 2 cents.

Your newly overhauled engine is far more likely to fail than your engine that seems to be running well with a minor leak. From a purely safety risk perspective, you’re currently flying the safer engine. 

[MBDiagMan]

On 7/12/2020 at 12:10 PM, bbakerco said:

Current engine is now past TBO at 2150 hrs.  Just came out of annual 2 months ago with compressions at 76/78/78/78 and no sign of engine wear in 50 hour oil changes.  The engine has had a minor oil leak that is presumed to be at the back bottom of the crankcase (from dye test) since I purchased it (didn't show up on pre-buy).  Nothing on the floor, just a small amount that gets blown around the engine compartment and ends up accumulating on nose gear doors and belly over time.  Other A&P's tried addressing it without success.  Can't be addressed without pulling engine and even then, no guarantee it can without resurfacing case halves.  So since the engine is past TBO, also needs new engine mounts and some new hoses.  Seems like the time to get it all done.  

I guess it's possible to pull the engine, try to fix the leak, reinstall with new mounts and hoses, but if that doesn't fix the leak, I'm out $$$ with an engine that is still past TBO.

Also, a Turbo Normalizer was installed in 08 (1200hrs) from M20TurboKits out of FL which doesn't appear to be in business any longer.  But they used a Rotomaster turbo and scavange pump and Rotomaster is here in PHX area so I'm going to check into getting that rebuilt.

That's about all I can think of.  If it weren't for the oil leak, needing new mounts, and hoses, mechanic thinks she'd be good for a few hundred more hours.

An oil leak alone, unless it is gushing so much oil that you can’t get where you need to go, does NOT justify an engine overhaul.  If it’s holding good oil pressure, making good compression (which it is) and not making metal along with running well, you stand to lose more than you gain.  Putting in a brew engine does not mean that everything will be perfect afterward.

[aviatoreb]

1 hour ago, bradp said:

Your newly overhauled engine is far more likely to fail than your engine that seems to be running well with a minor leak. From a purely safety risk perspective, you’re currently flying the safer engine. 

I have often wondered about this truism you just cited.  It is true exactly as you stated, but to my thinking, it is not the full story.

Here are two different questions:

Q1: If I plan to fly 100 more hours and then never fly again, then I will choose to fly behind an old and still running engine.

Q2: If I plan to fly thousands more hours, then I will choose the maintenance plan that will have the minimal probability of failure through the entire period.

An old but still reasonably running engine will gradually become worse, in 100 hours, or 1000hrs, or eventually the curve of probability of failure in the next hour graph, will rise, and eventually rise quickly.

A recently overhauled engine has a probability of failure in the next hour graph, that starts high and declines, and gradually becomes quite low and flat for a long time.

If I will MUST eventually change the engine, and so if I must eventually fly behind a new engine anyway, the goal of minimizing risk for long term, would be to change the engine before that rising risk of an old engine outshines the large but declining risk of a new engine, not in the probability of failure in the next hour graph, but the integral of that, integrated over a long time, the accumulated risk over thousands of hours.

Long story short - eventually the old engine needs to be changed and the hope is to change it soon enough but not too soon - and that said even despite new engines are a worry too, at least at first.

E

[bradp]

Totally agree with you prof EB.  Those two risk curves intersect.  I think the fact is that an old engine will probably tell you it wants to be overhauled before it goes quietly into the night... if you’re listening.  A new engine might suddenly shout stomp and scream like the toddler it is. 
 

It probably most depends on whether you have the tools to listen and you know what you’re listening to. 

[toto]

Just now, aviatoreb said:

I have often wondered about this truism you just cited.  It is true exactly as you stated, but to my thinking, it is not the full story.

Here are two different questions:

Q1: If I plan to fly 100 more hours and then never fly again, then I will choose to fly behind an old and still running engine.

Q2: If I plan to fly thousands more hours, then I will choose the maintenance plan that will have the minimal probability of failure through the entire period.

An old but still reasonably running engine will gradually become worse, in 100 hours, or 1000hrs, or eventually the curve of probability of failure in the next hour graph, will rise, and eventually rise quickly.

A recently overhauled engine has a probability of failure in the next hour graph, that starts high and declines, and gradually becomes quite low and flat for a long time.

If I will MUST eventually change the engine, and so if I must eventually fly behind a new engine anyway, the goal of minimizing risk for long term, would be to change the engine before that rising risk of an old engine outshines the large but declining risk of a new engine, not in the probability of failure in the next hour graph, but the integral of that, integrated over a long time, the accumulated risk over thousands of hours.

Long story short - eventually the old engine needs to be changed and the hope is to change it soon enough but not too soon - and that said even despite new engines are a worry too, at least at first.

E

This all sounds like the right calculus. 

I overhauled an engine at 2500 hours that was running absolutely perfectly. The thinking was that it couldn't keep going forever, and since the plan was to keep flying it for the foreseeable future, an overhaul was the best way to ensure long-term reliability. 

That said, oil burn and compression have been consistently worse since the overhaul (about 1000 hours ago) and I've wondered many times whether it was the right decision.

[GeeBee]

I recently saw an O-320 in a 172, running like a top at 2600 since zero time. The owner was so proud of it, swore it would make 3000 hours, then the head separated from the cylinder. The engine is no longer running, and the airplane is...no more.

 

[bradp]

3 minutes ago, GeeBee said:

I recently saw an O-320 in a 172, running like a top at 2600 since zero time. The owner was so proud of it, swore it would make 3000 hours, then the head separated from the cylinder. The engine is no longer running, and the airplane is...no more.

 

That’s a cylinder issue.  Which is an engine accessory.  Many cylinders don’t make it to 1000 hrs let alone 3000 hrs.  Cylinders should be considered separately.  Ask any IO-5X0 owner.  

[GeeBee]

Got, it. Pistons, rings, valves are no longer part of the engine and can be sent to any accessory shop. Which begs the question, why is the ECi cylinder AD listed under the engines rather than by themselves?

 

 

[aviatoreb]

Right - we shall see what happens but... in my tsio520nb at 1400 hrs my cylinders were eci and I was forced to dump them by that ad.  I made the difficult decision to replace the cylinders rather than overhaul this high time engine that’s been running well.  Now at 1660 hrs it’s still running well.  But I have all new cylinders - which changes the calculus a bit I think -  so how long I’ll let it run will take into account that yeah - new cylinders.  Hopefully I get a good bit more time.

Edited July 18, 2020 by aviatoreb

[EricJ]

2 hours ago, aviatoreb said:

I have often wondered about this truism you just cited.  It is true exactly as you stated, but to my thinking, it is not the full story.

Here are two different questions:

Q1: If I plan to fly 100 more hours and then never fly again, then I will choose to fly behind an old and still running engine.

Q2: If I plan to fly thousands more hours, then I will choose the maintenance plan that will have the minimal probability of failure through the entire period.

An old but still reasonably running engine will gradually become worse, in 100 hours, or 1000hrs, or eventually the curve of probability of failure in the next hour graph, will rise, and eventually rise quickly.

A recently overhauled engine has a probability of failure in the next hour graph, that starts high and declines, and gradually becomes quite low and flat for a long time.

If I will MUST eventually change the engine, and so if I must eventually fly behind a new engine anyway, the goal of minimizing risk for long term, would be to change the engine before that rising risk of an old engine outshines the large but declining risk of a new engine, not in the probability of failure in the next hour graph, but the integral of that, integrated over a long time, the accumulated risk over thousands of hours.

Long story short - eventually the old engine needs to be changed and the hope is to change it soon enough but not too soon - and that said even despite new engines are a worry too, at least at first.

E

There is a data- and experience-backed point of view that is an alternative to this.

https://blog.aopa.org/aopa/2014/02/11/roots-of-rcm

 

[Shadrach]

6 hours ago, toto said:

This all sounds like the right calculus. 

I overhauled an engine at 2500 hours that was running absolutely perfectly. The thinking was that it couldn't keep going forever, and since the plan was to keep flying it for the foreseeable future, an overhaul was the best way to ensure long-term reliability. 

That said, oil burn and compression have been consistently worse since the overhaul (about 1000 hours ago) and I've wondered many times whether it was the right decision.

So how did the 2500hr engine look upon disassembly? I’m guessing pretty good if you’re questioning it’s removal from service. I think people tend towards anthropomorphizing engines as though they age like humans. Even though we (I’m guilty as well) know better,  we use terms like tired, run out, past its prime, long in the tooth...etc. We know they don’t really age that way. Components that are operated at moderate temperatures while receiving proper lubrication (clean oil, preheated if needed) in environments that don’t foster corrosion should perform consistently for a long time. Performance should not peak and decrease gradually as it does with humans. If compression is good and the valves are opening to spec, an engine will run as strong at 1800hrs as it did 300hrs yet many will suggest it is ready for overhaul just because the numbers fall close to an arbitrary recommended age limit. I get that we need a proxy for powerplant value but I’m speaking strictly about operations.

Aircooled, internal combustion engines (in almost any application) can be built to a remarkably consistent standard. However, anecdotally speaking, I sometimes run into one that just seems better than its siblings. It is nuanced but still noticeable. I’ve ridden many of the same make and model motorcycles but one might pull just a touch harder or feel a touch smoother than the others. When I have a powerplant of any kind that is performing optimally, I really try to avoid messing with it.

Edited July 18, 2020 by Shadrach