1975 Mooney E with IO-360 A1A will need overhaul soon 2200 hours on engine

[jimluper]

Not using much oil and engine is running good with 75/80 on all cylinders BUT I know its coming.

Question is where is best place to get the cylinders overhauled? 

What is the most cost effective to zero time the engine?

For sure I am replacing the Cam, any suggestions on the best cam?

This is my first engine overhaul and look for guidance. 

[BrianWilkins]

I am currently getting my IO360 overhauled at Poplar Grove Airmotive in Poplar Grove, IL.  They overhaul to new specs and are fairly well known for the quality of their work.

https://poplargroveairmotive.com/pga-overhaul/

 

 

[Niko182]

Get it boroscoped and have someone knowledgable take a look. People take their engines to 2500-3000 hours all the time. No need to throw money at something thats working great.

[jaylw314]

3 hours ago, jimluper said:

Not using much oil and engine is running good with 75/80 on all cylinders BUT I know its coming.

Question is where is best place to get the cylinders overhauled? 

What is the most cost effective to zero time the engine?

For sure I am replacing the Cam, any suggestions on the best cam?

This is my first engine overhaul and look for guidance. 

"Zero timing" an engine can only be done by purchasing a Rebuilt engine, which is defined by regulation.  Any Overhaul does not, by definition, change the engine time.

I shouldn't speak for others, but I think most here would agree there's no reason to overhaul the motor unless you suspect a bottom-side problem (crankcase, crankshaft, camshaft, lifters), such as suspicious metal debris or oil analysis, or a measurable change in performance.

Cylinders are easily inspected by borescoping, so they can wait to be overhauled or replaced until needed.

I suspect most here would also suggest having bottom-side work at a motor shop like Jewell.  Some would even suggest that for cylinder replacements.  Mike Busch with Savvy Aviation has a webinar about the dangers of multiple cylinder replacement.

[1964-M20E]

If you are not leaking or using oil and everything else is looking good.  Keep flying it.  I'm doing an engine now because the one on my plane is leaking oil and not getting any better only about 1700 hours on the engine but I have flown it since 2012 and put about 800 hours on it.  Leaking at cylinder bases and a the case split.

The sawdust I keep putting in it doesn't seem to be slowing the oil leaks but when I take the filter off the oil is like black toothpaste coming out and doesn't drip down the back of the engine..

[Vance Harral]

2 minutes ago, 1964-M20E said:

I'm doing an engine now because the one on my plane is leaking oil and not getting any better

This may be what eventually triggers us, and I'm watching this thread with interest since our engine is about the same age as the OP.

We're currently at about 2175 tach hours and 25 calendar years () since overhaul on our airplane.  Oil analysis, borescope, and compressions all reasonable, takeoff and cruise performance right at book numbers, no metal in oil filter or pickup screen, oil consumption has been steady at about 1 quart every 10 hours since we bought the airplane in 2004.  Basically no indication whatsoever that it'll need an overhaul any time soon.  But... it leaks enough oil to make a giant mess inside/around the cowl and down the belly, even just a couple of hours after cleaning everything up.  We've addressed the easy stuff: valve cover gaskets, drainback tubes, etc.  But the main leak source is the gasket between the oil pan/intake manifold and the crankcase, which seems difficult to address (would have to disassemble so much to drop the pan that it feels like you may as well do an overhaul).  There's also some evidence it's seeping a little at the cylinder bases and/or case split, though it's just a drop or two if at all.  None of those leaks are individually concerning or reason to overhaul by themselves.  But collectively they indicate all the "soft seals" that are designed to last the life of the engine are timing out; and what bothers me about it is they could mask something more serious that you'd otherwise know about right away in a dry engine: crack in the case, loose accessory seal, etc.

[Bartman]

I too started my engine rebuild at 1950 hours due to multiple oil leaks and the main one at one of the cylinder thru studs but also at case mating surfaces. Had it not been for the leaks I would have continued flying past TBO and monitor closely, but it would have been with one spalled lifter that was discovered and would have continued to deteriorate. My crankshaft and gears were still good, but with the damaged cam and lifters it was only a matter of time. Also, the case mating surfaces were fretted and had to be scrapped. 

[cctsurf]

4 hours ago, Vance Harral said:

But the main leak source is the gasket between the oil pan/intake manifold and the crankcase, which seems difficult to address (would have to disassemble so much to drop the pan that it feels like you may as well do an overhaul).

An overhaul is MUCH more than you would have to have done to drop the pan.  Yes, there's a lot going on under there, but I would talk to a competent A&P or IA about the work involved before I would jump from oil pan gasket to overhaul.  Perhaps your other items add up to an overhaul for you, but I think you're trying to throw $15-20,000 at a $2,000 (or less) problem.

Just my $0.02, but from a CB, that's a lot of money...

 

[MikeOH]

Another fan of "if it's not broke, don't fix it". 2300 hours on mine, runs well, doesn't leak oil.  I'm in no rush to do anything but keep flying it

(Do you rush to rebuild your car engine if it's running well just because it has X miles on it?)

I swear TBOs are set by Lycoming's LAWYERS not the engineers

[201Steve]

... “I know it’s coming” plz explain the exacting science here

[Ragsf15e]

I’m also for not doing an overhaul too early, especially to “fix” problems that don’t really need fixed.  However, here are a few things to learn about when the time is right:

1. Factory OH, Rebuild, or new.  2 of those (Rebuild or new) come with “zero” time logbook.  Not necessarily zero time parts on a rebuild though.  Depending on age of your engine, you may not get core credit unless you opt for rebuild or new.

2.  Roller lifters - only available through a factory engine.  DLC lifters available through other overhaulers.  Both supposedly prevent the cam lobe wear due to corrosion on our old flat tappets.

3.  Overhauling accessories like fuel servo, mags, alternator, starter, oil cooler.  Factory engine comes with most of that, others depend on what you ask for.  How long has it been since your accessories have been OH?

4.  Generally people prefer new cylinders on an OH.  Factory engine only comes with new.  If you really want OH you can save a few bucks but most people agree new cylinders on the OH is the way to go.  If you have to change a cylinder on a 1500 hour engine and opt for OH, that might make more sense.  Price difference is roughly $2600 for new or $1600 for OH’d per cylinder.

The price difference between factory rebuild and field OH seems big until your engine needs a new case, crank, cam and all the accessories OH’d, then they are a lot closer.

If you buy a factory engine, you can have it waiting, ready to swap out instead of sending yours in for months to a shop.

Im definitely no expert but those are some things to read up on.

[Vance Harral]

5 hours ago, cctsurf said:

An overhaul is MUCH more than you would have to have done to drop the pan. 

I should have included emojis or elaborated.  I am not seriously suggesting that fixing an oil pan gasket leak is not much different from an overhaul.

But it is very invasive, expensive, and won't make the engine "dry" anyway - as I said, we have evidence of other minor leaks too.  The more of those that occur and the greater the rate at which they leak, the greater the risk of having a more serious problem masked.  So we're unlikely to replace the oil pan gasket, much more likely to keep living with it until "someday", when a collection of those leaks and/or other symptoms push us over the threshold.

I'm all for running these engines long, and I don't have any serious concerns about our 2200 hour/25 year engine today.  At the same time, my ideal endgame is accumulating enough small, compound, symptoms of wear, to the point we decide to pull the overhaul trigger under benign circumstances.  The alternative is to run it until gross malfunction.  Maybe that's cool if the gross malfunction is just a surprise bunch of unexpected metal in the filter at the next oil change, from parts we're going to replace during the overhaul anyway.  But if it's from a ruined crankshaft, or worse yet the engine throws a rod in flight, I won't be too proud of the extra hours of runtime we got in exchange.

The good news in our case is, we've already gotten everything we could ask from the engine, and everyone in the partnership is mentally and financially prepared for the overhaul.  The complex question in our case is simply estimating the point at which the relative risk of continuing to run the old engine crosses the risk of infant mortality in a new one.  There is no definitive answer for that, only speculation and gut feel.

[Vance Harral]

3 hours ago, MikeOH said:

I swear TBOs are set by Lycoming's LAWYERS not the engineers

Nah.  The manufacturers define TBO numbers because the FAA's engine certification standards require them to do so: CFR 14 Part 33, Apendix A, 33.3(a)(6).  Even the lawyers know a single number for all circumstances is bogus, but the companies have to pick something to put in the ICA, otherwise no type certificate.  If it were as liability-driven as your tounge-in-cheek comment suggests, there would be all kinds of efforts to get the 2000 hour TBO significantly reduced, or to push everyone much harder to value the calendar time over engine time.  But there aren't, even though plenty of engines don't get anywhere near TBO before some sort of catastrophic failure.

The number of aircraft operators running piston engines under anything other than Part 91 where it's not meaningful, is so small that there is no value in debating changing the existing recommendations.  Whether that's a cause or effect is an interesting debate, though.  One wonders if there might be a lot more piston Part 135 operations if TBO numbers were different.  The sad tale told in this Mooneyspace post seems relevant.

[M20F]

20 hours ago, jimluper said:

Not using much oil and engine is running good with 75/80 on all cylinders BUT I know its coming.

Question is where is best place to get the cylinders overhauled? 

What is the most cost effective to zero time the engine?

For sure I am replacing the Cam, any suggestions on the best cam?

This is my first engine overhaul and look for guidance. 

Oil burning is not an indication of anything unless you are burning an extreme amount or nothing at all.  Mike Busch as a great video “All About Oil” that speaks to this.  
 
Unless you are seeing issues on the valves, bad compression’s, etc. there is no need to overhaul a cylinder. 75/80 are fantastic compression numbers.  If you replace the cylinder reading 80 tomorrow with a brand new one, odds are the new one will be 78. 
 
About the only reason to do the case/bottom would be the cam.  If you bore scope you can see the status of it.  If the lobes are good then no point I can see to doing the case.  
 
TBO, Overhaul, Factory Reman, 0 time, etc. are all poorly defined and largely understood in the GA community.  All an airplane needs is IRAN (inspect and repair as needed).  This is essentially what part 135/121 does with progressive maintenance.  In short if it ain’t broke don’t fix it. 
 
Accessories are probably the most overlooked thing on the engine and much more likely to cause a problem then the power plant itself.  Mags, starters, injectors, etc. but again inspection can determine the need.  Exhaust system is another example. 
 
Airplanes are expensive enough, don’t go out of your way to spend money needlessly when it isn’t needed.  

[MBDiagMan]

I don’t understand.  It’s running good, good compressions.  Does it have low oil pressure?

If it does have good oil pressure and the other things are good and it isn’t making metal, why in the world would you overhaul it?

[cctsurf]

8 hours ago, Vance Harral said:

At the same time, my ideal endgame is accumulating enough small, compound, symptoms of wear, to the point we decide to pull the overhaul trigger under benign circumstances.  The alternative is to run it until gross malfunction.  Maybe that's cool if the gross malfunction is just a surprise bunch of unexpected metal in the filter at the next oil change, from parts we're going to replace during the overhaul anyway.  But if it's from a ruined crankshaft, or worse yet the engine throws a rod in flight, I won't be too proud of the extra hours of runtime we got in exchange.

You have a much higher risk of failure in new parts than you have at this point in the lifespan of an engine.  The statistics show that gross malfunctions happen after bad maintenance or with infant mortality (new parts or assemblies breaking), not with old, tested parts.  One of my airplanes has a bottom end that has over 3600 on major.  It has had 2 sets of cylinders on it.  The ONLY reason I need to do an overhaul on it is cam lifter spalling.  Even there, I have been running it at the direction of my IA until it doesn't make rated power.  A few oil leaks can be dealt with.  As someone mentioned, if you are not showing oil pressure issues, and your cylinders are showing good compressions, there is NO need to overhaul/rebuild.

It is, of course, your choice, but why spend the AMUs to repair that which isn't broken?

Mike Busch has a webinar on this:

 

[MBDiagMan]

Exactly correct.  Statistically you are much safer in a high time properly operating engine than flying behind an engine within about the first 250 hours.

[steingar]

A freshly overhauled engine is far more dangerous than one approaching TBO.

[Immelman]

20 hours ago, Vance Harral said:

But the main leak source is the gasket between the oil pan/intake manifold and the crankcase, which seems difficult to address (would have to disassemble so much to drop the pan that it feels like you may as well do an overhaul). 

Vance - my engine has 17 yrs/almost 1800 hours. Same situation, bottom end good, cylinders look good, but soft seals giving out.

This year I've chased down a bunch of oil leaks. But I've got one pesky leak in the same area (sump gasket). Have already done: Rocker covers done a long time ago, induction, oil drainback, prop governor OH recently, oil hoses to the cooler....

We haven't touched the oil pan yet. That seems like the last one. Just curious, have you tried anything? Re-torquing, exterior sealants (I'm assuming nothing along that gasket is pressurized)??

Edited February 3, 2021 by Immelman

[Andy95W]

On 2/2/2021 at 9:50 AM, jimluper said:

 

For sure I am replacing the Cam, any suggestions on the best cam?

 

I wouldn't be too quick to replace your camshaft, unless it needs it.  

There are lots of camshafts from the 60s, 70s, and 80s that soldier on just fine through multiple overhauls- but there are also newer ones that spall after 500 hours due to bad metallurgy. I'd rather have an old, good camshaft with new DLC lifters than an unknown brand new camshaft.

[Vance Harral]

1 hour ago, MBDiagMan said:

Exactly correct.  Statistically you are much safer in a high time properly operating engine than flying behind an engine within about the first 250 hours.

Well, yeah, but not literally forever up to infinite time.  There is a point on the far right of the "bathtub" curve where the theoretical risk creeps back up to about the same level as a newly overhauled engine.  That's the sweet spot we'd all love to get to under benign circumstances.

No disagreement from me that the overall fleet statistics show the right side of the bathtub way beyond published TBO, for engines that are run regularly, and ours is.  But anyone with a basic understanding of statistics knows that fleet numbers only apply to an entire fleet of machinery.  We don't own a fleet, we own one unit.  Deciding how to manage a single unit is a lot more like gambling.  We'll place our bet at some point, and it likely won't be any time soon, for all the reasons elucidated in this thread.  But it's still totally reasonable, as the engine goes past 2000 hours of service, to start thinking more about what triggers feel right to you/me/us.  We use all the right tools to guide us: compression, cutting filters, pulling the pickup screen, UOA, periodically checking performance against book, etc.  But it's simply undeniable that feel/guess/hope is a component too, unless your philosophy is to keep running until gross failure.

The end game I'm hoping for is to see a definitive knee of the curve in some combination of declining compressions, uptick in oil consumption, slightly reduced performance, more than the very occasional sliver/flake of metal in the filter, etc.  If several of those things came together over the course of a year, I'd gladly overhaul the engine that winter.  I'd also fully understand that doing so exposes us to a whole new set of risks for the next couple hundred hours.  But like everyone else, I'll tell myself the lie that I guessed perfectly, and that the risks over those first couple hundred hours are no worse than the risk of having continued to run the old engine.  In reality, no one knows the answer to that question for a single unit, so you just tell yourself whatever makes you feel good.

[Vance Harral]

22 minutes ago, Immelman said:

We haven't touched the oil pan yet. That seems like the last one. Just curious, have you tried anything? Re-torquing, exterior sealants (I'm assuming nothing along that gasket is pressurized)??

When we first definitively identified the pan gasket as a source of leaks, we did try re-torquing the bolts near the point of the leak.  Didn't help, and the mechanic was not surprised.  For one thing, you can't get to all the bolts without removing the exhaust and other components, so we only re-torqued "some" bolts and not others.  Doing that around a flat surface is always a little sketchy.  For another, once a gasket loses enough suppleness to start seeping, squeezing it tighter is a Hail Mary idea anyway.

We have not tried the gooping on exterior sealant.  I'm not opposed to that trick necessarily, just seems like an Aggie-engineered thing (I can say that cuz I iz one), that's about as likely to cause a new problem as it is to fix an old one.

At this point we simply live with the leaks, and have instituted a voluntary program in the partnership of trying to wipe down the cowl after every flight, so we have a better chance of noticing if they suddenly get worse.  It is amazing how little oil it takes to create a giant mess.  All these leaks have no observable effect on the number of hours we go between adding make-up oil.  It's right at one quart every 10 hours today, just like it was in 2004.

[JoeM]

I have installed two Gold Seal overhauled engines from Western Skyways and was very pleased, not only with the quality of the engines, but also their after sale service and support. Very competent people, and it's nice not to have to wait weeks or months to get your plane back in the air. Just order the new engine and swap it out. Longest downtime is for accessory overhauls, but they will send those too if you need speed, and give core credit for your old ones. 

[Immelman]

8 minutes ago, Vance Harral said:

 It is amazing how little oil it takes to create a giant mess.  All these leaks have no observable effect on the number of hours we go between adding make-up oil.  It's right at one quart every 10 hours today, just like it was in 2004.

Ok interesting thanks. Late last year both my governor and oil hoses started leaking, and those were creating a big mess like you describe. The sump gasket - FOR NOW - makes enough to have some oil on the bottom of the sump after 2-4 hours flying, without much of that beginning to drip down to the bottom of the cowl. It sounds like its a lot less than you are dealing with. Of course it won't get better...

[Vance Harral]

Sounds like we're kindred spirits.  We have also R&R'd the prop governor (twice), and replaced oil lines, in addition to the other stuff I mentioned, over the last 17 years, all primarily to deal with oil leaks.  I've come to the conclusion that chasing oil leaks is just regular maintenance on airplanes that only fly 100-ish hours a year.  I know it's de-rigueur to pooh-pooh the calender-time-based component of TBO recommendations, and I concur with Mike Busch on that sort of thing.  But it's not as if the concept is simply made up out of thin air.  Gaskets and seals and their ilk really do wear just with the passage of time, to some degree.  So those of us that take decades to reach 2000, or 2500, or 3000 hours, are going to have more of these sorts of problems than the flight school 172 that gets its 3K in 6 years.

When I call our oil leaks a "mess", that may reflect my personality as much as any objective measure.  Let me try to be a little more scientific about describing it.  If I completely wash the airplane, then we run it for three, one-ish hour flights, without cleaning, here's what we'll see:

• 2-3 definitive black streaks of dirty oil running back from places like the aft edge of the port side cowl cheek, a stop-drilled crack in the front nose bowl, etc.
• 2-3 more streaks running back down the nose gear doors, which I think is being blown out the cowl flaps
• enough oil pooled at the bottom of the cowl flaps to be noticeable, though not enough to actually drip
• a thin film of oil around the cowl mouth, and a smattering of oil on the windshield (we have the old "guppy mouth" cowl, which actually has a net outward airflow at cruise speed)
• an irritatingly dirty belly for having only flown 3 flights, though some of that is just ordinary combustion residue out the exhaust rather than un-burned oil

Looking around the airport, I've seen worse, so I don't think any of the above is really that big a deal.  But it's objectively worse now than it was a decade ago.  Used to be the airplane would stay looking pretty decent for a dozen flights between cleanups.

Edited February 3, 2021 by Vance Harral