Horizontal scratches in cylinder wall?

[MrGiggles]

This isn't chainsaw related, but maybe you guys can help me out.

I bought a Troy Bilt 4 Stroke trimmer in 2006. I didn't research before I bought like I should of, but it worked flawlessly for 3 years. Easy to start, and it ran very well. Around mid this summer, it started making a noise at idle. Like a tapping noise that would drag down the engine and stall it. I looked at it once and couldn't find anything out of the ordinary so I continued using it. It got worse and worse until it stopped working completely because it would not run and was partially seized. Upon tearing into it nothing seemed out of the ordinary. Everything was in very good shape. Except the cylinder. There is a 1/2 strip of random gouges mid way into the cylinder wall, They are very deep, probably around 1/32" of an inch. It goes all the way around the cylinder as well. This has us puzzled. Maybe the coating of the cylinder flaked off? The second compression ring on the piston was broke as well, but that would cause vertical scratches correct?

I would take pics my camera batteries are dead.

On the positive side, I replaced it with a Stihl FS90R. No comparison between the two. I love it.

 

[dragrcr]

piston slap or (rock) skirts worn down and piston rocks in the bore, especially when cold as aluminum expands more that steel, so the piston will be even more loose on cold start, then run under load before warmed up. a;so usually makes a interesting egg shaped mark on the skirt

 

[wigglesworth]

Let me pioint out the first mistake.......

Around mid this summer, it started making a noise at idle. Like a tapping noise that would drag down the engine and stall it. I looked at it once and couldn't find anything out of the ordinary so I continued using it. It got worse and worse until it stopped working completely because it would not run and was partially seized.

But you did redeem yourself quite nicely!!

On the positive side, I replaced it with a Stihl FS90R. No comparison between the two. I love it.

Just promise us if the FS90R starts knocking, you stop using it. LOL

 

[MrGiggles]

Let me pioint out the first mistake.......


But you did redeem yourself quite nicely!!


Just promise us if the FS90R starts knocking, you stop using it. LOL

Yes, pretty stupid on my part I know. There's nothing I can do about it now.

Let's just hope the Stihl doesn't start knocking, ever.

 

[MrGiggles]

piston slap or (rock) skirts worn down and piston rocks in the bore, especially when cold as aluminum expands more that steel, so the piston will be even more loose on cold start, then run under load before warmed up. a;so usually makes a interesting egg shaped mark on the skirt

The piston was in really good shape, Nothing was worn much at all. Do you have any pics of the egg shaped mark? I know that I didn't race the engine was cold, I usually let it warm up for 30 sec before using it.

 

[MrGiggles]

Just priced a new cylinder and ring set, and it's 75.00 shipped.

These are the pics:

 

[dragrcr]

WOW, that is not from slap, maybe the ring was spining? that looks pretty intence!

 

[Paul001]

Just priced a new cylinder and ring set, and it's 75.00 shipped.

These are the pics:

Do you have a picture of the piston/rings?

 

[dragrcr]

i think your buddy came over at night and used a dremmel on your cyl and put it all back to play a joke on you:greenchainsaw:

 

[MrGiggles]

i think your buddy came over at night and used a dremmel on your cyl and put it all back to play a joke on you:greenchainsaw:

None of my buddies know enough to tear apart a weedeater.

Do you have a picture of the piston/rings?

I can get some later. It looked pretty normal except for the broken ring.

 

[blsnelling]

Looks like a manufacturing defect to me I don't see how the rings/piston could have caused that.

 

[MrGiggles]

Looks like a manufacturing defect to me I don't see how the rings/piston could have caused that.

Good. Maybe I can convince MTD to send me a cylinder even though it is 1 year out of warranty.

Here are pics of the piston.

 

[Mad Professor]

The guy who machined the cylinder had an extra bottle of scotch at lunch.

 

[rmotoman]

Your rings look broke. Not sure how that accounts for the wear in the cylinder.

 

[ironman_gq]

maybe the ring stuck or broke and the rest of it spun in its groove cutting the gouge you see

 

[7sleeper]

The guy who machined the cylinder had an extra bottle of scotch at lunch.

You really believe somebody machined that?

:greenchainsaw:

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