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-   -   Making a Little Bit of Metal (https://vansairforce.net/community/showthread.php?t=135233)

BillL 05-14-2017 04:53 PM

Quote:

Originally Posted by lr172 (Post 1173006)
No way to identify cam/lifter wear without a visual inspection (pull jug and look).
Larry

You can put the cam on the base circle and see if the hydraulic lifters are out of range - dead giveaway. If that occurs, the plane should be grounded.

The pieces can break off the edge of the cam lobes after the followers become concave (if they are not rollers) and create edge loading.

Lots of speculation - a good magnified photo should narrow the scope.

Something is definitely happening, but just when it needs repair is not clear yet from information available.

MartinPred 05-14-2017 07:58 PM

Power?
 
Bill,

If the lifters were out of range, would that affect performance? The engine has been running like a champ.

I'll see if I can get better pictures of the particles and maybe get them analyzed. I hate to start performing exploratory surgery unless there's no other choice.

-Matt

BillL 05-14-2017 08:37 PM

Quote:

Originally Posted by MartinPred (Post 1173065)
Bill,

If the lifters were out of range, would that affect performance? The engine has been running like a champ.

I'll see if I can get better pictures of the particles and maybe get them analyzed. I hate to start performing exploratory surgery unless there's no other choice.

-Matt

Probably not early in it's progression, if that's it. Maybe after lash range was exhausted, the CHT would creep downward relative to other jugs as the first indication. Email sent.

lr172 05-14-2017 09:36 PM

Quote:

Originally Posted by MartinPred (Post 1173065)
Bill,

If the lifters were out of range, would that affect performance? The engine has been running like a champ.

I'll see if I can get better pictures of the particles and maybe get them analyzed. I hate to start performing exploratory surgery unless there's no other choice.

-Matt

Once a cam/lifter wears enough to be noticeable it is not likely to stop; It will typically take out the whole lobe. I have no first hand experience with lycoming cam failure due to spalling. However, an engine that is throwing off chunks the size shown in your pictures is not doing well in some area. Most cam/lifer wear will not generate chunks of steel like you are showing. Once they go, they can go fast, but it is more typical wear, with much finer debris, due to surface imperfections and resulting bad geometry (i.e. concave vs convex).

I'll restate, ferrous chunks of that size need to be identified as to there source so that you can assess your risk.

Larry

Robert Anglin 05-15-2017 07:08 AM

Martin.
 
I can give you two cents from the peanut gallery. Pictures are sometimes hard to read and inturpret so from what you have posted I can guess but not be sure. The dark black stuff looks to be normal coke and stuff you see all the time. But the metal that is both in the finger strainer and on the magnet is a dead giveaway there is something in the engine going away. If I understand this history of this power plant correct, it has been stored from time to time and not run for months at a time. What you are seeing is what we would expect for long dry store, start damage. It is better to pull a jug or two now than wait or guess if or when something may turn loose internally in this power plant.
Sorry, I think you need to get this stuff checked and identafied then if it looks to be gear, cam, lifter or whatever metal go in and put your finger on the problem. You will be money and peace of mind ahead.
Hope this helps, Yours, R.E.A. III #80888

cajunwings 05-15-2017 08:02 AM

Making Metal
 
I was putting together a comment but Robert Anglin very clearly stated what I was thinking. Have dealt with this issue a several times and his advice is spot on.

Don Broussard A&P, IA etc etc
RV9 Rebuild in Progress
57 Pacer

Guy Prevost 05-15-2017 08:07 AM

I hope your results are different than mine.
For the last year I've been seeing metal in the filter on my RV-10's io-540. I found one small shard in my pick-up screen. All told, less metal than you are picturing. I had my mechanic look at what I found and he wasn't too concerned. My oil analysis always comes back normal. For piece of mind, I pulled my #3 cylinder since there was some evidence of past corrosion in there. The cylinder looked as expected. However, the tappets I could see had severe pitting and there was visible cam damage.

My engine is at Barrett as we speak. My cam and lifters are shot. There is some scoring on the crank which may or may not polish out. I should have stopped flying it earlier--it may have saved me the cost of a crank.

My engine came off a Piper Twin, and then only flew 200 hours in 7 years in my RV-10 before I bought the plane. I knew I might run into this, but I was hoping not!

Best of luck!

Guy

brian257 05-15-2017 08:28 AM

As to the question on loss of performance on the worn cam, I doubt you would notice anything. I have a Mustang 2 with an O-360 that I bought about 5 years ago and prior to my buying it it sat for a while and apparently got some rust on the cam which is all it takes to ruin one. Engine ran just fine until a minor prop strike and I pulled the engine apart to magnaflux the crank. I was shocked to see two cam lobes with nearly an eighth inch of wear on the end of the lobes and correspondingly ate up tappet bodies. I expected a nice increase in performance when I put the new cam in, but two engine experts said I probably would not notice any difference and I could not even tell when I flew it. And this is a plane that I keep detailed performance records on.

MartinPred 05-20-2017 10:28 AM

Sharp Pointy Particles
 
Here's a better photo of the particles on the magnetic drain plug.



I'm planning to pull the #2 cylinder when I get a free weekend. That one had the lowest compression (72) on the last annual.

-Matt

lr172 05-20-2017 11:26 AM

Quote:

Originally Posted by MartinPred (Post 1174287)
Here's a better photo of the particles on the magnetic drain plug.



I'm planning to pull the #2 cylinder when I get a free weekend. That one had the lowest compression (72) on the last annual.

-Matt

Quite a bit of metal there. Something is wearing aggressively. I would try to borrow a borescope or buy one of the dental cameras. Inside of a cylinder, I would think that only broken rings or missing pin plugs (they couldn't have worn away or you would have seen a LOT of aluminum in your filter) could cause that kind of metal. Wear on the cylinder wall should be quite visible with that kind of metal production. This would be a much faster way to check each cylinder before you pull more to check the cam. If they all look good, next step would be to pull jugs to check the cam. Seek advice on the best cylinders to pull for best visual access to viewing the cam. You should also pull the rocker covers to look for damage. Less likely, but easy to do. If it is not inside the cylinders, you're going to need a full tear down anyways, though I suppose it could be coming from the accessory case.

If you happen to have a buddy with an analyzer to determine the alloy of the fragments, Lycoming can tell you where the metal is coming from. They offered to do this for me when I was making small metal and couldn't confirm the source. I later figured out it was aluminum and never used their service. My piston pin plugs were wearing away.

Larry


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