Stihl piston examination

[MustangMike]

You can sand the high points on the squish band but sticking sand paper to the top of the old piston.

Lube the piston sides, and I moved it back and forth with two large paint stirrers.

Be sure to check the cages on the bearings, and the piston pin bearing.

 

[MustangMike]

Pecker tracks like that on the piston crown and squish band indicates debris from a failed bearing in the bottom end.

Or something ingested if someone ran it w/o a filter.

 

[RIDE-RED 350r]

Or something ingested if someone ran it w/o a filter.

True..but generally speaking it's hard to imagine something hard enough to leave those well defined imprints being somehow ingested...strange things happen though.

 

[MustangMike]

The mark on the crank does support your theory. Hard to imagine something ingested would get down to the crank.

Was there any metal in the muffler??? Is it screened?

 

[RIDE-RED 350r]

Well I'm thinking more like something able to damage the innards of the saw like that is probably going to be too heavy to be floating around in the air to be ingested by the saw in the first place.

Any time I've seen that kind of damage, it was lower rod or crank bearing failure.

 

[brandonstclair20]

The mark on the crank does support your theory. Hard to imagine something ingested would get down to the crank.

Was there any metal in the muffler??? Is it screened?

No metal was in the muffler


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[brandonstclair20]

I am thinking this saw had some kind of major failure in the past and was rebuilt. I will definitely check over everything very carefully. Thanks for the input everyone.


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[traffic903]

not being smart. What does it hurt if the squish band is dinged up. ?
I have a 346 with a top end like that I intend to use. Hadn’t really even thought of cleaning it up

@smokey7 covered it mate. Pre-ignition is very hard on internal components.

 

[Fruecrue]

You can sand the high points on the squish band but sticking sand paper to the top of the old piston.

Lube the piston sides, and I moved it back and forth with two large paint stirrers.

Be sure to check the cages on the bearings, and the piston pin bearing.

I’d bet, at this point, ol Mustang’ could swap bearings on a saw with nothing but paint stirrers.

 

[leadfarmer]

Here's a little somthing for you guyshttp://www.madsens1.com/saw_piston_fail.htm

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[Adirondackstihl]

I know what I would do if it were mine.
The cases would be split.
Bearings replaced.
You’re already 75% of the way there