Brand new MS391 meltdown

[ZeroJunk]

Can he get the chain brake band back in proper place and stay there ?


I have gnawed plastic out of them, but not that bad I don't think.

 

[StihlsawuserMS361]

My .02, if it were a car, I'd just pull the license plates!

 

[Okie]

Was the chain brake on?

I've seen similar where the saw's chain brake was on or dragging enough that that area would overheat is why I ask.

 

[pioneerguy600]

Was the chain brake on?

I've seen similar where the saw's chain brake was on or dragging enough that that area would overheat is why I ask.

Post#1 start of thread.

 

[Okie]

Was the chain brake on?

I've seen similar where the saw's chain brake was on or dragging enough that that area would overheat is why I ask.

Must have been left on the fast idle of the throttle after it was started with the chain brake on. (did not blip the trigger throttle to get off of fast idle)
It's a safety thing starting with the chain brake on per the owners manual to help reduce the chance of spilling a hot cut of coffee in the crotch area and lawsuit time. I do not use the chain brake when starting my saws, but I know how to start a chainsaw safely.

Chalk that one up to learning experience. You won't forget that one.
You are not the only one that has experienced such.

 

[ZeroJunk]

Sorry for the delay on update. I cooked her good boys. As expected not covered by warranty. My stihl dealer wanted the same price to fix it as a new one so i got a new saw.
What do you guys think about trying to Salvage this saw?
View attachment 1241693

I replaced the crankcase on one this morning. The whole thing has to be replaced. And, they likely figured a new oil pump, etc. It takes a few hours. Not sure how many they figured or at what rate.

 

[stihltech]

Looks like what was on my bench yesterday. The charring combined with the clip coming off the clutch when the chain was jumped. New oil pump elbow, feed line , clutch spring and retainers, sprocket bearing and e-clip. Cleaned the boogers off the drivers,it up and back on the wood

 

[JimR]

I picked up a MS250 that the guy did the same thing too but not as bad.. I salvaged it with my Dremel tool and a bit of work. No new parts were needed.

 

[Vintage Engine Repairs]

$100 for a new oem case, I’d get one, new seals and new clutch springs - will be as good as new. https://www.ebay.com/itm/324863121401

 

[Old2stroke]

Not really serious damage, don't believe you would need a new engine case, clean it up and see how it looks. Do a pressure/vac test on the crankcase to check the seal. I've seen worse and the seal survived. If the worm gear on the oil pump is in good shape and rotates freely, there is probably nothing wrong with it that can't be repaired, although a new one is reasonably cheap. If the needle rollers in the clutch bearing are held in a metal carrier, it's probably still good. Before buying parts, stick it all together and get it running, check the oil pump for output and if the clutch engages at about the same rpm as the new saw, the springs are good. Is there really any serious damage with the brake mechanism?

 

[Stumpzero]

It looks like the crankcase should still be servicable, I would try picking as much melted plastic off with care, if the saw had had many more hours on it there would have been a coating of oil on the crankcase that would have prevented the melting plastic from sticking. In your case though the saw was too new for a coating of oil to be there, lets hope the melting plastic did not stick too well to the underlying plastic crankcase.

 

[ZeroJunk]

$100 for a new oem case, I’d get one, new seals and new clutch springs - will be as good as new. https://www.ebay.com/itm/324863121401

Yep. Anything else is going to be half ass. The tabs that hold the brake band in place are gone. Do they have to be there ? Don't know.
But, I can understand why a dealer would want no part of trying to make chicken salad out of that.

 

[ZeroJunk]

View attachment 1242342

That's pretty slick.
Good job.

 

[Stumpzero]

I have the new parts on order . I did not get the case at this time . The chain break strap fits in place very nice and firm after the case clean up with a drimel tool. Before and after cleaning the case.

 

[Stumpzero]

Yep. Anything else is going to be half ass. The tabs that hold the brake band in place are gone. Do they have to be there ? Don't know.
But, I can understand why a dealer would want no part of trying to make chicken salad out of that.

I will post a photo of the brake band when the new one comes in. I test fit the old one and was very firm. I put the old parts back on and the clearance is good and everything seems to work right. Once the new parts come in I will know if the case cleanup worked or not. Stay tuned.

Yep. Anything else is going to be half ass. The tabs that hold the brake band in place are gone. Do they have to be there ? Don't know.
But, I can understand why a dealer would want no part of trying to make chicken salad out of that.

 

[ZeroJunk]

I will post a photo of the brake band when the new one comes in. I test fit the old one and was very firm. I put the old parts back on and the clearance is good and everything seems to work right. Once the new parts come in I will know if the case cleanup worked or not. Stay tuned.

Cool. It looks good to me. Once you get the outer cover on I'm not sure where it could wander off to.

 

[Stumpzero]

Cool. It looks good to me. Once you get the outer cover on I'm not sure where it could wander off to.

It’s held in place with a screw at one end and attached to the brake mechanism at the other and neither of those areas was effected by by the melted plastic. The areas that the band might ride against are still there.

 

[pioneerguy600]

View attachment 1242342

Looks quite good, the oil pickup/black rubber hose at bottom right in thee top pic looks like it has been heat damaged, should be replaced. The vert top brake band holding lug looks to be either missing or still under some of the melted plastic, only tell for certain when the brake band is installed and all linkage connected to the brake handle.

 

[heimannm]

MS291 in this week, customer said it was hard to start. Clutch bearing cage was completely melted fusing the drum to the crankshaft.







It cleaned up O.K.



Pressure and vacuum were good. New clutch and drum were installed, old clutch shoes just rattled like a baby toy.

Mark

 

[Stumpzero]

Looks quite good, the oil pickup/black rubber hose at bottom right in thee top pic looks like it has been heat damaged, should be replaced. The vert top brake band holding lug looks to be either missing or still under some of the melted plastic, only tell for certain when the brake band is installed and all linkage connected to the brake handle.