Ms261 help!!!

[jb-chainsaws]

just started tearing into a customer's ms261, the usual suspect sprocket bearing went and trashed the oil pump. Just got it stripped and cleaned and found the crank seal absolutely pummelled and the outer race of the bearing spins in the case almost as if it's supposed to do it's that slick. Anyone ever seen this before?? It's got me stumped.




I'd have cleaned it before pulling the seal but it literally fell out

 

[Canadian farm boy]

I've seen that on several saws. 038,044,066 etc. Usually it happens because of an overly tight chain combined with operator abuse.
Tight chain takes out the sprocket bearing. Customer retightens the chain and then takes out the crank bearing.
If the crank bearing is spinning in the case the case half is probably toast.
I'd bet the piston is also toast. Cylinder likey has a bunch of transfer as well.
That saw is dickered IMO.

 

[jb-chainsaws]

I've seen that on several saws. 038,044,066 etc. Usually it happens because of an overly tight chain combined with operator abuse.
Tight chain takes out the sprocket bearing. Customer retightens the chain and then takes out the crank bearing.
If the crank bearing is spinning in the case the case half is probably toast.
I'd bet the piston is also toast. Cylinder likey has a bunch of transfer as well.
That saw is dickered IMO.

That's what I thought, but the cylinder is in great shape! Pulling 150psi! I've told the customer the saw needs a new case half as it's toast and he's leaving the saw with me. So whilst I've been bored I have an update:



I figured the case half is toast anyway, so I'm gonna have a play and see how long it runs for. When it dies I'll save the crank for the next customer I see that has one of these with the heat treating issues. I've peened round the outside of the outer race with a small flat blade, driving the mag alloy up against it. Outer race is now tight as a duck's a**. Next job is fill the groove with JB weld and run the sucker just for *s-words and giggles

 

[Duane(Pa)]

Some people just shouldn't have chainsaws...

 

[Wood Doctor]

Operator abuse usually causes it while trying to get the cutting job done. I've seen the needle bearing almost cut in half along with the rim sprocket and clutch drum as the operator kept tightening the chain. Eventually the chain tensioner cannot go any further out. That saved the crankshaft, but the rest were toast.