Thought I would share this with anybody that may be looking to buy something. I share a hangar with several other guys. One of them just bought an awesome Stinson with a Franklin. The engine only had 140 hours SMOH. The only problem is that Major was done 14 years ago. I noticed last week that his airplane was next door in the maintenance hangar getting the annual done. Today when I went out to fly his plane was back in it's spot in our hangar only there was NO engine on it! When they pulled the cover they found some pretty major corrosion on the cam, lobes, and lifters. He had been flying it for a couple of months and put about 50 hours on it like that. The cam was pitted up pretty good. Not sure how this didn't come up in the prebuy. Poor guy thought he was going to get many years and hours out of that engine and now he's going to have a many thousand dollar annual on his hands. I'm sure to you experienced guys your probably thinking duh but to some people numbers are everything. Lessons learned just because it's low time does not mean it's a good engine and engines that sit for years are obviously subceptable to corrosion issues when the oil finally runs off the parts.

That's really unfortunate for the owner and is a good reminder for all of us. In the right conditions the pitting can occur in months, not years. Time is definately a factor on these engines and a really intensive prebuy is very important. The only way this could have been noticed during the pre-buy would have been to start pulling cylinders to have a look at the lower end and this gets costly for the potential buyer and some owners don't want thier airplanes molested to this level. 14 years and only a 140 hours should have been a red flag to a potential buyer. It's not a deal breaker, it just needs to be looked into a little closer. Hope it all works out ok for the owner.

My Lycoming 0-360 had 1100 hours SMOH and I needed every one of those 900+ hours remaining to be trouble free. In 65 hours after I bought it, the cam began lunching itself to the tune of spoonfuls of lobe dust in the filter.

The previous owner fell on hard times and couldnt bring himself to sell so he moved it out of a hangar and parked it outside for almost 4 years. I was leery but I bought the plane anyways.

I'm actually happy to have a new motor even though it hurt (17K). At least I can care for it correctly, fly it a lot, and have some confidence over the mountains with my family inside.

that sucks, i know of a Stinson in Helena that has been sitting for 12+ years full of fuel, bird shit all over. he thinks it is Worth big money and that it will start right up and go fly with no problems, he was not happy with me when I referred to it as more of a project plane since every thing should inspected

I don't know about other engines, but Rotax has a number of items to be inspected or replaced based on time. There's quite a few at 5 years.

tom

And, on the other hand, most of our engines go well OVER TBO, as in 2500 hrs plus. They are overhauled on condition.

Use an engine regularly, and take care of it, and they should almost all go well over TBO.

MTV

My C175 is one that sat for a looong time. The last annual before this year was in 86. I was told the engine was "pickled" but I seriously doubt that. It has just over 500 hrs but it has had 2 oil tests so far and both came out good. I am really hoping it holds up.

We replaced the oil pump housing and gears and the oil pressure runs right at the top of the green. The more I run it the better it seems to start and run. The compression was low on one cylinder when I got it but now it's right up there with the other ones now. I's a "Mystery" how that happened?

My friend has a 96 Chev full sized truck with a 4.3 six cylinder. He uses that "Engine Restore" every oil change, and he has since he bought it new. He only changes filters every other oil change. He just passed 400K and it still runs strong. If I didn't have a certified plane I would be real tempted to use it in my plane.

My O-470R is 45 years old and is still a virgin. 1600 hours TT. Oil analysis and compressions are good. Runs smooth and makes good power. But, it's getting pulled because I just don't feel safe behind an engine that old. It's an exchange so I won't get to look at its' insides, although I wish I could.

Jumpy, I would feel a lot safer behind your engine than a new one. If your engine has run fine for all these years you know you got a good one. Yours is tried and true. New stuff makes me nervous. I have bought 2 new cars in my life and both were the highest maintenance cars I owned with repeated trips back to get things fixed for the first year. I will stick to the old stuff any day over new stuff with new unproven parts and labor. Just my opinion.

You don't need to tear an engine down during pre-buy to check out internal corrosion ... a good remote boroscoping of the engine internals, particularly the camshaft, can tell a mechanic a lot about the kind of problems this poor airplane buyer got himself into with that low-time engine.

I had the pre-buy mechanic do that on my Cherokee's O-360, which had about 1,400 hours SMOH but only about 300 STOH, and the inspection didn't reveal any cam corrosion, it had good compressions too, and the engine has run very strong since I bought it a year and a half ago.

If you have corrosion issues in the cylinders or piston rings, it'll likely show up in low compressions.

As one or two others pointed out, ya gotta be real leery of any low time/high age hangar queen. The best indication of a reliable airplane is one that's been flown regularly - at least an hour or more every week in the logs throughout it's life is ideal.

Jaerl wrote:Jumpy, I would feel a lot safer behind your engine than a new one. If your engine has run fine for all these years you know you got a good one. Yours is tried and true. New stuff makes me nervous. I have bought 2 new cars in my life and both were the highest maintenance cars I owned with repeated trips back to get things fixed for the first year. I will stick to the old stuff any day over new stuff with new unproven parts and labor. Just my opinion.

a friend commented the other day, most engines that fail, do so in the first 100 hours of an overhaul. There's much to be said for one that's known and running well.

The guy doing my annual right now is also the mechanic for the local air taxi. He has an engine in a 206, 900 SMOH, already needs 2 cylinders. Same operator, 207 that is about 30 hours away from TBO and they haven't touched it. Same pilots flying them both, same engine shop did the overhauls, same new factory cylinders, etc., etc. I think sometimes you get a good one, sometimes you don't.

The corrosion is also interesting. I have a red-tagged crankshaft from a C90 that got pranged 2 years ago. It has been laying outside my hangar in the rain since it was replaced. It is showing some rust now, but it took nearly a year before it showed a spec, at least to the naked eye. Oh yeah, I forgot to mention that we get 90 inches of rain annually. The camshaft didn't get hurt, so I can't say for sure how it would hold up given the same circumstances.

Needless to say, after reading a bunch of the corrosion stories guys share, I now use the Camguard. It must work, because it's expensive. My airplane probably doesn't fly 2 hours a month in the winter time. It is sitting at 1400 SMOH, 12 years ago. So far, so good (hear me knocking on wood now?).

gb

This summer my mechanic put a new engine in one of the local Flight School's planes. I was over a week later and it looked like he was doing another one. He told me the new engine he just put in had broke a valve or something and had filled the engine full of metal.

It was under warranty but that won't do you much good when your flying a really crappy glider at night or with no place to land. I learned a long time ago, if it works, don't fix it.

nmflyguy wrote:You don't need to tear an engine down during pre-buy to check out internal corrosion ... a good remote boroscoping of the engine internals, particularly the camshaft, can tell a mechanic a lot about the kind of problems this poor airplane buyer got himself into with that low-time engine. I had the pre-buy mechanic do that on my Cherokee's O-360, which had about 1,400 hours SMOH but only about 300 STOH, and the inspection didn't reveal any cam corrosion.....

A bore-scope is great for checking out the inside of the cylinders (hence the name "borescope"), but please tell me how to borescope the cam or crank without some sort of teardown. With the exception of the Franklins with that peekaboo trapdoor in the top of the crankcase, you'll need to pull a cylinder to look at the innerds. In the case of the original post, it's too bad the mechanics didn't open up that trapdoor during the prebuy-- at the cost of a few minutes & a new gasket, it woulda been pretty easy to spot that cam/follower corrosion. I know a couple guys who've been stung like this with Lycomings, with their top-mounted cam they seem to be a little more suseptible to this problem than Continentals.
On the other hand, a buddy of mine has bought several engines (both Lyc & Cont) and/or airplanes that have sat for a long time and he hasn't had a problem with any of them. Just dumb luck I guess.

I'm not familiar but it sounded like on a Franklin you can pull a pan and gain access to the cam and the crank unlike Lycomings. I guess that didn't happen on the prebuy.

yes Franklin has a cover on top that you can pull easy and get a good look at the guts. not normal to do at annual unless there is metal in the oil

hotrod150 wrote:

nmflyguy wrote:You don't need to tear an engine down during pre-buy to check out internal corrosion ... a good remote boroscoping of the engine internals, particularly the camshaft, can tell a mechanic a lot about the kind of problems this poor airplane buyer got himself into with that low-time engine. I had the pre-buy mechanic do that on my Cherokee's O-360, which had about 1,400 hours SMOH but only about 300 STOH, and the inspection didn't reveal any cam corrosion.....

A bore-scope is great for checking ut the inside of the cylinders (hence the name "borescope"), but please tell me how to borescope the cam or crank without some sort of teardown. With the exception of the Franklins with that peekaboo trapdoor in the top of the crankcase, you'll need to pull a cylinder to look at the innerds. In the case of the original cost, it's too bad the mechanics didn't open up that trapdoor during a prebuy-- at the cost of a few minutes & a new gasket, it woulda been pretty easy to spot that cam/follower corrosion. I know a couple guys who've been stung like this with Lycomings, with their top-mounted cam they seem to be a little more suseptible to this problem than Continentals.
On the other hand, a buddy of mine has bought several engines (both Lyc & Cont) and/or airplanes that have sat for a long time and he hasn't had a problem with any of them. Just dumb luck I guess.

I'm not a mechanic, so I can't tell you precisely how the cam lobes are checked on a Lycoming O-360 (i.e., which hole you stick the scope into). A friend I fly with quite a bit is a former Cherokee 180 owner (he's a Bonanza driver now), and he suggested the boroscoping of the cam lobes when I was shopping for a plane last year. When I asked the A&P I hired to do the pre-buy in Georgia to check out the surfaces of cam lobes for corrosion with a boroscope, he didn't hesitate and agreed to include that in the inspection, and he told me afterward that he was able to check out the cam lobes visually and said they were clean as could be.

Maybe another more mechanically-capable poster here can point out the particulars of how this gets done for hotrod

man this is an interesting read for me. Being new to the ownership thing I always was looking at numbers-granted I did keep in mind if the plane wasn't running and sitting outside the combination could be less than desirable.

A big question for me being a new owner: Does oil type play a big role in engine longevity? (not withstanding proper oil changes, topping off, operating treatment, etc). The operator I work for always uses nothing but exxon elite in our pawnees and supercub and so I adopted the same oil in my airplane having seen the guts when he changed them out and they were unbelievably clean looking. It also seemed to drop my CHT about 15-20 degrees.

FLYNAKD wrote:man this is an interesting read for me. Being new to the ownership thing I always was looking at numbers-granted I did keep in mind if the plane wasn't running and sitting outside the combination could be less than desirable.

A big question for me being a new owner: Does oil type play a big role in engine longevity? (not withstanding proper oil changes, topping off, operating treatment, etc). The operator I work for always uses nothing but exxon elite in our pawnees and supercub and so I adopted the same oil in my airplane having seen the guts when he changed them out and they were unbelievably clean looking. It also seemed to drop my CHT about 15-20 degrees.

Flynakd,

The answer to your question depends upon what oil you're using, and how often you change the oil and filter. The Exxon oil and Aeroshell 15/50 are probably equivalent products - each has their supporters/users. You definitely want one or the other for your engine. Change your oil and filter at least every 40-50 hours, per the manufacturer's recommendation ... and possibly more often depending upon the use the airplane gets and the environmental conditions you're subjecting the aircraft to.

Being run regularly (i.e., at least weekly is great) is an important part of airplane longevity. Running the engine at regular cruise power frequently prevents the accumulation of moisture in the internals which can lead to the kind of corrosion that was the subject of the opening post in this thread. The worst thing for a plane is to just sit, either outdoors, or even in a hangar (especially in a humid climate), for months or years at a time.

Duane

nmflyguy wrote:....Maybe another more mechanically-capable poster here can point out the particulars of how this gets done for hotrod

Oh I know how it gets done on a Lycoming- you pull one (or more) cylinders, shine a bright light in there, & eyeball things. It's a good idea to do so, but it's more involved than most people get on a pre-buy, unless specifically directed to do so: you have to remove baffling, exhaust, etc to get the cylinder off. Takes a fair amount of time. If you end up looking at several airplanes, and do this with every one of them, it could get pretty spendy. I would only do so once everything else passed muster & I was certain that this was "the one".