O-235 corroded camshaft; advice

[corroded_camshaft]

Hi guys I need some advice. I got a call from my mechanic earlier and as if the annual wasnt full of problems already, a corroded camshaft had to be added to the list.

I have to talk with my AME again and get him to re-explain everything, an over-the-phone conversation wasnt the best way to tell me Im screwed and then me ask him the right questions. Anyways, what he told me was that he had to pull a cylinder to do some work on the exhaust system and while it was off he noticed corrosion (severe?) on the camshaft, and then mentioned something that sounded like 'the bearings are [insert explicit]' I havent been able to see the plane yet and he said he packed everything up so I assume the cylinder is back on but if now I'll see it sometime this weekend hopefully.

A little history on the engine/airframe: I bought the plane nearly 3 years ago, the engine presently has about 380 hours since major overhaul, which was done in April 1993 by Leavens. The engine is a Lycoming O-235-C2C and the airframe manufactured in 1970. Throughout 70-77 the airplane flew over 100 hours per year and then was sold and never flew more than 40 hours for the next 10 years. From 87 to 91 it didnt fly at all. Overhauled in 93 and again from 99 to 03 didnt fly at all (except one flight in 00 and one in 03)

According to the logbooks #2 cylinder was pulled in 92 and the inspected due to the time elapsed without flying. Overhauled in 93 and returned to Leavens a few months later to "correct rough running / stumble @ 1500-2000 r.p.m."

The airplane was then sold in 2004 and I purchased it in 2007. Originally it seemed to be run on W80 oil, and was switched to 20W50 sometime before the overhaul, and I switched to 15W50 when I bought it.

Here is a list of air times per year since overhaul:

1993 - 93.5
1994 - 86.4
1995 - 33.5
1996 - 10.4
1997 - 3.4
1998 - 2.3
1999 - 0.0
2000 - 0.7
2001 - 0.0
2002 - 0.0
2003 - 1.6
2004 - 10.2
2005 - 33.9
2006 - 28.3
2007 - 41.6
2008 - 34.4
2009 - 32.7

So the engine hasnt had an easy life. On top of that I dont see anything in the logs hinting to the fact that the engine was put in any kind of storage while it wasnt flying. It's had a history of #3 cylinder being weak (50s to 60s compression except high 70s the last two years). My AME suggested the cost of a new cam could be between 4000 and 6000 and Im not sure whether thats parts/labour/shipping or not, and even then theres the possibility the shop will find more things wrong (hey, its been a bad annual this year, more bad news wouldnt be surprising at this point)

So either way right now, I cant even afford the new camshaft and Im looking for a second job. And Im thinking maybe its just worth doing a major overhaul on the thing and screwing myself over even more, but at least I'll have a good engine.

So, what do you guys think? I absolutely love the plane and selling it is definitely not an option Im considering.

[AEROBAT]

For that kind of money you could probably get a half time engine in decent shape. Look in Barnstormers.

[iflyforpie]

I would imagine that price would include everything. I think a camshaft is about $600, but you need to re and re the engine, pull the jugs and split the case, etc etc. I do find it hard to believe that the AME is telling you the bearings are screwed in situ through a cylinder hole. If they are visibly screwed like that, you are lucky the engine turned over at all.

IIRC, the camshaft bearings are simply cast into the aluminum case, which would mean two new case halves. But most likely he meant the lobes and/or lifters.

This is the tough part about owning an aircraft, even one with such an economical and usually bulletproof engine. I would stick with the evil that you know, though, rather than possibly buying someone else's problem with a half time engine.

[Bulawrench]

i would send it for overhaul or buy a re manufactured engine. Look at manufacture's recommendations for time but idle engines are going to have trouble not just a camshaft. If you don't fly over 100 hours a year it may be cheaper to rent. I have have several that had many other problems after they come apart.

[ahramin]

I had to replace my cam this summer during an overhaul and it was $500, didn't get a core credit as the old one was junk. This engine had less than $300 hours on it. The entire labour costs for the overhaul were under $3000, but that doesn't included removal and re-installation of the engine.

I would suggest that you follow the advice of others and either have the entire engine overhauled or get another one. It doesn't matter how many hours since last overhaul. Just hope your crank is ok.

[c170b53]

Was it making metal?

[Hornblower]

Was it making metal?

That would be my question, along with why did the AME pull a cylinder, do some work on the exhaust??? Weird .. what kind of an aircraft is it? Was he being overly fastidious (sounds fishy to me)? Normally I (and most other AMEs I know) would only pull a cylinder it it was indicted as necessary for troubleshooting by some kind of impending malfunction, i.e.: metal in the screen. The other reasons for pulling a cylinder would be an internal inspection following an extended period of unuse, or hot immersion. After the long periods of unuse on that engine, it wouldn't surprise me if the cam or lifetrs were corroded, however if the engine was not making metal, it should not be something that requires immediate attention.

If it was not otherwise making metal, I would put it back in service and check it again after 1 hour, 5 hours 10 hours, 25 hrs and at the next annual. The cam may have some discorloration, even some light pitting, and not spall in service. If it does spall at some point you are no further behind, you will still need to replace the cam and lifters. You will always find evidence of spalling in the screen/filter.

[corroded_camshaft]

Thanks for the replies:

@AEROBAT - I know I could get another low-mid time engine and toss it on, but I've always been told - and it makes sense to me - to 'stick with the evil that I know' as iflyforpie put it.

@iflyforpie - I took a look at various links through Google searching for Lycoming camshaft and found a lot listed around the 500-600 dollar mark, so I know now that 6000 dollars has to include more, at least it makes me feel a little better.

I do have to talk to my AME again though, he mentioned something about bearings and mentioned other things too. Bushings? I dont know. I'll find out on Wednesday.

@Bulawrench - if I had a million dollars, heck even 50,000 to afford an overhaul, I would. But I dont Actually I was reading the overhaul manual today, good source of info. I know on a top overhaul the case isnt split, but if I have to get the cam done, would it be a good idea to get four new cylinders as well (and when someone says 'I put a new cylinder in' does this normally also include piston, rings, valves, etc?)

@ahramin - How does core work? If mine is corroded I'd assume the value they'd give me - if any - for it would be minimal. Might be better to keep it as a strange memento?

I know my AME and I will talk about this, but getting the cam - or any engine work - done at a shop, whats the typical procedure, costs, and downtime?

@c170b53 - I honestly have no idea. The engine/airframe has no oil filter and I've never checked the pressure screen. My AME does at every annual and never mentioned anything about it. I've never done an oil analysis either as Im told A) theres no place here and B) its useless unless you have done it over a period of years to establish a baseline comparison.

I've never noticed anything while draining oil though and I checked the suction screen once and it looked "clean", though I dont have any experience on the subject.

The engine has always run well for me (although a weak #3 cylinder when I bought it, at 58 and went as low as 48 before going up)

@Hornblower - When I brought the plane in for an annual, I thought to myself, man this is going to be a simple quick one, I have no defects to bring up, and as per last years' annual, my AME hadnt mentioned anything special. But two weeks into it I got a call Started with a new nose gear and fork, some structural repair, and went on to a muffler that had broken... plates of some sort inside. So the entire exhaust system was taken apart and the muffler shipped out. A month later it still hasnt come back But my AME said that to do something with reassembly of the exhaust or whatnot, he had to remove a cylinder. And thats when he noted the corrosion on the cam.

What questions should I ask my AME? I'd like to see inside the case - out of curiosity too - is there anything specific my untrained eyes should look for? Again, going to ask him but what would be the next steps, approximate costs, downtime. Where would I want to ship the engine to, or where could I ship it to. What kind of work would I want to get done "while they're at it"? New gaskets? new piston rings?

Thanks guys

[Bulawrench]

Even for us in the industry, It always better to talk to the engine shop directly.
Try the guys at Pro Aero. Airplanes cost money even when they sit around.
Why not try slick 50.

[cgzro]

I had a similar problem, my AEIO-360 was not used much in the 15 years prior to me purchasing it and of course after a few hundred hours my camshaft/lifters started to go.

In my case it was obvious something was 'up' because about 50 hrs before it started making metal. At first the metal was just very light flat flakes with no 3rd dimension to them then it started to make pieces that were a little bit fatter. Around this time it started to foul plugs rather badly all the time (the metal flakes were falling on the cylinders and scratching the walls) so at the annual we pulled a cylinder. What we found were lifters that looked like the surface of the moon with a few pieces of metal that were not just flakes off the face of the lifters but actually crossing to the side and having a bit of thickness to them. I swear there is one piece about 1/2 mm by 1/2 mm that I took from the screen that I can fit to its spot in a lifter

Here is a picture of the amount of metal I pulled from my oil screen at three oil changes at 558hrs, 581 and 606hrs. You can also see the two front lifters.

http://www.freewebs.com/gzro/metal-medium.jpg

So if it were me, I'd want to see the camshaft and lifter faces for myself. I'd also want to see the contents of the oil screen. Honnestly its easy to open up an oil screen and you will know whats going on yourself.

I'm not sure what Lycoming says about a tiny bit of surface rust on a lifter or camshaft lobe, I've not seen anything specific, but of course they do talk about how much metal and what type of metal is ok.

Anyway its always worth asking for several opinions on the subject.
Perhaps take pictures and send them to Lycoming for a 2nd opinion. I agree that its not easy to see bearing issues through a cylinder deck unless its really serious so you may have misunderstood.

Good luck and sorry to hear about it. I know how expensive these bloody things can be .. good thing they are so much fun to fly!

Peter

[ahramin]

corroded_camshaft, I'm not sure what a normal core value is for a camshaft as I have only replaced one once. There was no core value because one lobe was worn down so far that it was probably causing a power loss. The lifter was beat up, though not as bad as the ones in the above picture.

My engine had 300 hours and 20 years on it. There was never any metal in the filter until the incident which caused me to split it (nothing to do with the cam, swallowed a valve) but the cam was far gone.

I think you are getting good advice here, and I would definitely go and look at everything the AME has to show you, and have him explain it until you understand thoroughly what the problem(s) are. Then get some other opinions.

[cgzro]

Personally I'd not re-use a camshaft or lifters if I'm splitting a case. I'd go with as much new stuff on the bottom end as possible, except obviously case and crankshaft . I'd not be too concerned about re-using in-spec top end parts because they can of course be more eaisly replaced at moderate cost down the line.

Peter

[LousyFisherman]

Warning: I am not an AME or a mechanic, and I am not much of a pilot either

Thanks for the replies:
I've never done an oil analysis either as Im told A) theres no place here and B) its useless unless you have done it over a period of years to establish a baseline comparison.

Agat Laboratories in Calgary offers a service where you mail them a sample and they email you the results ($28/sample I believe). You pay in advance, they provide all the packaging etc. PM me if you want more details, they are a client of mine.

To an experienced AME, a single analysis can be gold even without the history. A high reading of any type of metal usually indicates a problem. I believe they use their past experience with similar engines as the baseline. The advantage of a history is that small increases in metals can be detected and this may indicate a problem that can be detected early and fixed cheaply. The history of a particular engine can be established with as little as 2 analyses. If the third shows large increases then ...... Of course if you have been doing it for years then your baseline is even better, and you yourself can detect the changes.

My ownership group does an analysis at every oil change done on our C150 - Continental O200, I do an analysis once a year on my car. Cheap at the price as far as I am concerned.

YMV

LF

[cgzro]

Yes, oil analysis can be very helpful. Here are the trends in PPM that go with the pictures of oil screen contents & lifters I showed you above. I was doing regular oil analysis throughout the event:

METAL\ HOURS 462 488 512 534 549 568 592
-------------------------------------------------------------------------------
ALUMINUM 6 7 5 5 14 26 37
CHROMIUM 4 4 3 3 21 9 6
IRON 38 38 29 30 340 161 149

You can clearly see the spike happening around 540hrs about 20 hours before I started pulling metal from the oil screen. Presumably the iron flakes off the lifters/cam lobes, those little pieces fall on the cylinder walls and start causing aluminum wear.

I think if I were doing real IFR or nasty cross county type flying I'd probably want to do regular oil analysis but the tricky thing is what do you do when you see a spike? The usual reaction is .. well lets just monitor it. So you have to decide up front. If you do oil analysis and you start to get some spikes .. are you going to ground he plane even if the oil screens are clean and the engine is running fine? If not, if you are going wait for some physical problems to appear, then the oil analysis has not really helped .. except perhaps to keep you closer to home and out of hard IFR etc. conditions.

I think that the most important thing is to open the oil screen regularly, and at the first sign of problems start pulling the screen/filter much more frequently. Anything more than a 1/2 dozen or so flat flakes of iron (magnetic) is not good unless you are in breakin period.

Peter

[corroded_camshaft]

I went to see the plane today. All cylinders were on the engine but it appeared that #1 cylinder may have been the one removed. The nuts holding the cylinder to the crankcase looked like they had some wet oil on them whereas all other nuts - and these ones previously - looked like they had dried oil. A piece of tape was wrapped around one of the push rods on #1 as well with something written on it but I couldnt make out what it said. Maybe 'rusty' or something similar.

Have to wait until Wednesday. Should I ask that the cylinder be taken off so I can see inside? Or is that just wasting the AME's time? (or - assuming he's going to bill me for it - my money)

[iflyforpie]

I went to see the plane today. All cylinders were on the engine but it appeared that #1 cylinder may have been the one removed. The nuts holding the cylinder to the crankcase looked like they had some wet oil on them whereas all other nuts - and these ones previously - looked like they had dried oil. A piece of tape was wrapped around one of the push rods on #1 as well with something written on it but I couldnt make out what it said. Maybe 'rusty' or something similar.

Have to wait until Wednesday. Should I ask that the cylinder be taken off so I can see inside? Or is that just wasting the AME's time? (or - assuming he's going to bill me for it - my money)

Yes, absolutely take a look at it. It isn't too hard to see what is good and what is crap. If the AME said the engine was unairworthy, he shouldn't have put the jug back on until you had seen it. After all, he's not going to sign it out, is he?

Should be his dime to take it back off (am I saying this ). You don't put something back together that is broken. If he was trying to protect the innards of the engine, he should have just slid the jug on and not torqued it or put any of the valve train and manifolds back together. Or better yet, get a piece of cardboard or some poly and cover the hole.

Lyc pushrods are often easy candidates for corrosion as well, but the tape might also be for intake/exhaust identification. Can be a pain in the ass if you get them mixed up and valve clearances are now out of whack...

If you can, post some pictures. Not only will it give us armchair generals a chance to make a better judgement, it is educational for us as well...

[cgzro]

I'd want to see it myself, take some pictures, send them to the mfgr etc. Compared to the cost of a rebuild the time to take it off put it on are pretty trivial.

If your mechanic as reassembled it, torqued it down etc. its because he expects it to fly again ...... he may tell you to fly it but he may want to monitor it more closely...

Peter

[Hornblower]

My advice is:
If it is reassembled, there is no point asking him to take it apart again. I assume it's not making metal since he surely would have mentioned that prior to removing the jug (I still can't believe that he had to take a jug off to work on the exhaust). Repair or replace what is necessary to be airworthy, and fly the engine locally for a few hours then pull the screen again. If the cam is bad, it will show in the oil screen (or filter if that's the case). A wearing cam lobe will not lead to catastrophic failure in the short term. Make sure the valve lash is set correctly; does that engine have solid lifters?? Excessive valve lash will also cause premature cam wear.

[corroded_camshaft]

Ok Im drafting a list of questions I should ask my AME about:

- Why did you have to pull the cylinder for the exhaust?
- Which cylinder did you pull?
- What did you see inside, you mentioned corroded camshaft, how severe, and what else was bad?
- Did anything show up on the pressure screen?
- Did anything show up on the suction screen?
- Why was the cylinder replaced on the engine?
- Can you remove it so I can look inside.
- What is the meaning of the green tape on the pushrod on #1 cylinder?
- You mentioned 6000 dollars to get this fixed, what does the '6000 dollars' include?
- Was the cylinder you pulled off in good condition?
- Should I get new cylinders?
- Should I get new piston rings?
- What can I do to help preserve and maintain the engine?
- What is the next step?

I cant think of anything else to ask. I can call up today and I should be able to finally get a look at my invoice so far though. And tomorrow, the engine and my AME.

[iflyforpie]

- Should I get new cylinders?
- Should I get new piston rings?

Don't ask that or he might get ideas... .

If the leak downs are pretty low, now might be a time to do a top overhaul since the labor for removing and installing the jugs is already spent on splitting the case for the cam. Most likely, the engine shop could re-ring, hone, and re-seat your jugs for far less than a new set.

But don't beat a dead horse. If your leak downs are above 60/80, you still have a healthy top end. Continental lets you go down to ~45/80, but if you are this low, chances are there is a jug replacement near in your future.

[Hornblower]

Good list of questions, but I agree with pie, if the compressions are good, leave 'em (as long as no leakage from the valves). By rights, and according to regulations, you should be the person making calls on what needs to be done. In fact there is no regulatory relationship between the signing of an annual inspection and the airworthiness of the aircraft. The AME should sign (with a maintenance release) the inspection as being completed regardless of the number or type of snags. It is then up to you as the operator of the aircraft to determine what is an acceptable (and legal) defect to fly the aircraft without rectifying. In practice this rarely works since most AMEs want to control the aircraft operation as well as the conduct of their maintenance.

[PJ1]

Good list of questions, but I agree with pie, if the compressions are good, leave 'em (as long as no leakage from the valves). By rights, and according to regulations, you should be the person making calls on what needs to be done. In fact there is no regulatory relationship between the signing of an annual inspection and the airworthiness of the aircraft. The AME should sign (with a maintenance release) the inspection as being completed regardless of the number or type of snags. It is then up to you as the operator of the aircraft to determine what is an acceptable (and legal) defect to fly the aircraft without rectifying. In practice this rarely works since most AMEs want to control the aircraft operation as well as the conduct of their maintenance.

I'm sure this defence will work perfectly in front of the civil aviation tribunal along with the insurance company's. The owner operator should be the last person to deem airworthyness.

[Hornblower]

Why? And defence against what? And ... what tribunal? And since when is airworthyness {sic} a matter of deeming?

[corroded_camshaft]

I got to talk to my AME again, and called up Leavens as well (first). This is what I was told:

From Leavens:
They said likely the reason my AME pulled the cylinder is because he broke a 'stud'. A new camshaft would be about 700 dollars, 800 dollars for a set of new lifters (8), 230 dollars for new crankshaft bearings, a mandatory replacement apparently. And 250 dollars for new gaskets. In all they said about 2000 dollars of parts, and 3000 dollars of labour. One item they cautioned about is that if the camshaft has been having bits breaking off, they could have fallen onto the piston skirt and then gone up and scratched the cylinder walls.

When I talked to my AME he confirmed cylinder #1 was removed. He mentioned the camshaft had some corrosion, the lifters were gone, and the pushrods on #1 were corroded as well, and a good chance the rods on the other cylinders are as well. (didnt mention pushrods to Leavens because at the time I didnt know) When I asked him about the bearings he said he didnt know, so I probably miss-understood him on the initial phone call. He said he put the cylinder back on to keep the inside of the engine protected, but the nuts arent torqued. I asked if I could see inside and he didnt want to. Its a very busy time of year for everyone one right now so I can understand that.

I got the contact information for another overhaul shop in Quebec; Aero Atelier. Has anyone heard of them before? They seem to be closer and my AME hinted that they'd be cheaper, and I'd be able to drive the engine over to them rather than pay (he said about 300 dollars each way) to ship it.

As an aside, I'd really like to see the inside of the engine, but I've already been charged 3.5 hours when he took the cylinder off and re-installed, and I cant afford another, I have the overhaul manual and the engine isnt airworthy anyways. Is this something I could do myself?

On another note, I was able to glance at the snag sheet and there's 29 items listed so far The compressions were listed very low, I cant remember for sure but it was something like 21/46/71/76 Historically, #3 has always been weak, 50s to 60s but the last two years its been in the 70s. #1 and #2 have always been in the 70s. I asked my AME about this and he said it was due to the engine being cold, not run before the compression was taken. Hope he's right, those numbers are scary.

[niss]

He doesn't want to take it off? Isn't that what you are paying for?

And he did the compression check on a cold engine? Shouldn't he be doing it after the runup for RPM check while the engine is still warm? Whats the use in doing a leakdown test if nothing is expanded properly and fitting the way it should?

As an aside, I'd really like to see the inside of the engine, but I've already been charged 3.5 hours when he took the cylinder off and re-installed, and I cant afford another, I have the overhaul manual and the engine isnt airworthy anyways. Is this something I could do myself?

AFAIK only if you are an AME or willing to bump your plane down to the Owner Maintenance cat.

Have you used this AME before? How has he been? How much is he charging you for the Annual if you dont mind me asking? Is it a flat rate or per hour?

Good Luck, its situations like this that keep me up at night! Those goddamn Lycoming Cams!