MS661c bites the rubber?

[tickbitintn]

It's soft plastic, on a few of the bits I can see a curve, and a mold line down the middle of it. An inner and outer curve so I'm guessing it's the doughnuts of death rubber washers...
Lots of buildup in muffler and on cases near muffler exit...

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[tickbitintn]

Grooves aren't too bad.. a final cleaning is still needed... Intake boot looks like the one in the a.s. thread...

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[tickbitintn]

This is the first 661 I've had my hands on...
Does this intake boot look the same as the "newer" style as talked about in that older a.s. thead?

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[tickbitintn]

Thanks, that's what I was thinking...
Had a feeling that was the old style boot...
Was the old style boot used for any length of time without the washers?
Wonder if Stihl would do anything about this failure....

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[BuckthornBonnie]

Thanks, that's what I was thinking...
Had a feeling that was the old style boot...
Was the old style boot used for any length of time without the washers?
Wonder if Stihl would do anything about this failure....

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I'd try to call em. They're honoring another 661 meltdown for my dealer that in other years would have been a GFY response.

 

[CR888]

If its under warranty and you have a half decent dealer it should be warrantied. The washer was a bandaid temp fix to prevent the boot collapsing. Then the updated boot not requiring extra support came out. The fact this 'factory added washer' got ingested is no ones fault besides the design engineers. If they truly stand behind their product which is their flagship saw they 'should' help you out. Let the customer dealer dance begin.

 

[mdavlee]

A lot of these dealers register the pro saws with 90 day warranty

 

[Wood Doctor]

That piston with fused rings is really on the exhaust side not much different from half a dozen big Stihl saws that I have worked on in the past five years (066, 650, 660, etc.). Operators push them really hard in the cut. In really big logs they get hot and they burn out.

Sometimes it's a lean carb setting, but most of the time they just plain burn out from heat. I rebuilt the top end of yet another one three days ago.

 

[tickbitintn]

That piston with fused rings is really on the exhaust side not much different from half a dozen big Stihl saws that I have worked on in the past five years (066, 650, 660, etc.). Operators push them really hard in the cut. In really big logs they get hot and they burn out.

Sometimes it's a lean carb setting, but most of the time they just plain burn out from heat. I rebuilt the top end of yet another one three days ago.

In this case...
I'm going to go with rubber washers
(that were used as a bandaid fix for an inadequate intake boot design)
that were ingested into the bottom end causing a lack of lubrication between the piston and cylinder
(due to chopped up rubber bits smeared all over them)
as the cause of failure.
Other factors being that it is:
a M-tronic,
has just over 6hrs of run time,
a clean air filter,
a sharp chain AND
a short (25") bar...

There are MANY ham fisted operators out there including people that most likely touched or came near this saw..
But I'm not pointing the finger at them this time!

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