Stihl MS 291 burnt out after 1 hr

[lone wolf]

Close up of brake band/oil pump worm gear
View attachment 398902
inside brake band facing bar area
View attachment 398900
facing handle:
View attachment 398901
inside drum
View attachment 398899
outside of drum
View attachment 398904
opposite side
View attachment 398905
clutch
View attachment 398903

Let me know if you guys want more pictures/different angles. Work was cancelled for me due to snow so I have some time to look this stuff over.

Am I to infer from the grooving on the outside of the drum that for whatever reason the brake band was dragging on the clutch, hence the excessive heat? Does anyone see wear on the inside of the drum indicative of clutch slippage? I only see a little bit of melted residue, which would seem to point to something between the brake band/clutch drum causing the heat.

I'll let the experts decide.

Looks like it was in contact now dont it?

 

[watsonr]

I'd say the clutch drum expanded due to heat and contacted the brake band. The clutch shoes themselves are severely worn and you can see the drag marks... means it was slipping. Even the inside of the clutch drum shows excessive wear.

If your going to fix that saw, put new seals in as well, that one side is probably toast!

 

[west041]

Looks like it was in contact now dont it?

I agree. But that leaves open the question, why did this happen? I know I didn't engage the chain brake. Clutch slippage is one thing, that would make a hell of a lot more sense to me.

From what I have gathered, for the drum to have groove marks on the outside would be telltale signs of chain brake abuse, correct? I guess what I'm asking is if there is any conceivable situation where there would be heat generated by the chain brake with it in the off position. Because I still can't see how I'd have operated it with the brake on. And I didn't set it down at high idle with the chain brake engaged either.

 

[west041]

I'd say the clutch drum expanded due to heat and contacted the brake band. The clutch shoes themselves are severely worn and you can see the drag marks... means it was slipping. Even the inside of the clutch drum shows excessive wear.

If your going to fix that saw, put new seals in as well, that one side is probably toast!

Oh, now that would be a more conceivable situation. Somehow I operated in such a way that there was clutch slippage. If that is what the pictures show there (I can't pick out clutch shoe wear just by looking at it), then I can accept that.

The dealer recommended new seals and a new engine case.

 

[lone wolf]

Oh, now that would be a more conceivable situation. Somehow I operated in such a way that there was clutch slippage. If that is what the pictures show there (I can't pick out clutch shoe wear just by looking at it), then I can accept that.

The dealer recommended new seals and a new engine case.

What seems to be wrong with the case?

 

[west041]

I don't know, but it's on the estimate. You should ask them

 

[lone wolf]

I don't know, but it's on the estimate. You should ask them

Well look at it.

 

[CTYank]

I was talking about "so angry" because you told me to G.F myself, usually people that are angry say that. I was only suggesting that those kind of things happen. I definitely don't condone such behavior though. I personally did not threaten anyone, including yourself. Simply implying that a few of you guys should not use your superior knowledge to beat a guy up who just ruined his fathers new saw. Some day the guy might really track you down. I'm sorry if what I Said was totally inappropriate for you CTYank. I hope I don't get arrested. I Think I might be a little too pretty for jail.

Sure didn't look that way to me. Westy was given good advice based on the limited info he shared. and he was prompted many times for really conclusive pix. An experienced, competent sawyer should have known by the smell that something really bad was going on in a light-duty saw. Yet he insisted on people signing on to his agenda. Given that, he was treated pretty gently, IMHO.

You like to get cute with your assumptions. Understand that threatening/menacing are not a giggling matter, in most jurisdictions.

 

[Knobby57]

I'd say the clutch drum expanded due to heat and contacted the brake band. The clutch shoes themselves are severely worn and you can see the drag marks... means it was slipping. Even the inside of the clutch drum shows excessive wear.

If your going to fix that saw, put new seals in as well, that one side is probably toast!

Yup what he said . That clutch was slipping . It probably hit the band when the bearing melted


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[watsonr]

Yup what he said . That clutch was slipping . It probably hit the band when the bearing melted
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yep, not a lot of wear marks on the outside but some.

 

[a. palmer jr.]

Maybe the saw makers should put a warning light on the top of the saw to let you know that the brake is on while running.

 

[Definitive Dave]

I looks at least on my screen like the crank end is blued like it got hot too, just wondering if the crank bearings might be compromised as well.
I am not sure if I would rebuild that one.
DDave

 

[watsonr]

it's blue and brown... why I said the seals are probably toast as well

 

[west041]

Sure didn't look that way to me. Westy was given good advice based on the limited info he shared. and he was prompted many times for really conclusive pix. An experienced, competent sawyer should have known by the smell that something really bad was going on in a light-duty saw. Yet he insisted on people signing on to his agenda. Given that, he was treated pretty gently, IMHO.

Take it easy guys, don't get into it on my behalf. I've apologized and moved on, and you should too. I said some stupid stuff, but treemonkey wasn't setting a record for empathy either.

Maybe the saw makers should put a warning light on the top of the saw to let you know that the brake is on while running.

These are the kind of bonehead responses that got us into this mess in the first place. The time for sarcasm and cheap shots is over, let's just try to keep it civil, k? I think most people would agree that I would know if I had the brake on, and it seems from the responses to the pictures thus far that the culprit is increasingly looking like clutch slippage that led to a lot of heat in the brake band area.

 

[west041]

What seems to be wrong with the case?

I don't know, but it's on the estimate. You should ask them

Well look at it.

Maybe I'm missing something, but you need to be more clear whether you're making a sarcastic remark or trying to help me out with my problem. I'm just trying to give everyone the info they need.

 

[sunfish]

Part of the reason for all the sarcasm, is most folks who have run saws very much would have known something was wrong before the saw got that hot.

This is also one reason I prefer metal cases and outboard clutchs... Just sayin.

 

[super3]

Get the brake band out and the pump drive (what's left of it) out of there and it will be more clear if the plastic is too far gone for repair.

 

[lone wolf]

Maybe I'm missing something, but you need to be more clear whether you're making a sarcastic remark or trying to help me out with my problem. I'm just trying to give everyone the info they need.

I mean just look at it to see if it really needs repair. I cant tell from the pic but what is wrong with the case anything? I don't see it?

 

[west041]

This is also one reason I prefer metal cases and outboard clutchs... Just sayin.

I prefer them as well. All my saws are older and metal. Nobody reads what I write, it wasn't my saw.

Part of the reason for all the sarcasm, is most folks who have run saws very much would have known something was wrong before the saw got that hot.

I see this arrogance in my work field as well. People always love to act like it would never happen to them, until it does. Everyone makes mistakes.

 

[west041]

I mean just look at it to see if it really needs repair. I cant tell from the pic but what is wrong with the case anything? I don't see it?

Still looks usable to me. If it was my saw I'd just roll with it.