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Heavy Oil Saw

MS261 M-Tronic Clutch Drum/Bearing/Crank

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This sounds more feasible .  All what I said was from memory and written on hear in the past . Never had a 261 myself .

I’ve read from all different forums, including this one, most posts were made a few years ago, as the saws were newish. As there wasn’t anything recent, I’m trying to find out if the problem was ever pin pointed (by a Stihl dealer or small engine mechanic). Once a problem arises complaints and questions galore, loads of speculation, then sometimes a solution arises, but I just couldn’t find it, even with the mighty google.
Another theory I found was a batch of cranks weren’t surface hardened properly, leaving them susceptible to wear.
Looks like we’ll never know, as Stihl weren’t forthcoming with a statement.
Thank you for all your help though, it is appreciated.
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Hi Heavy Oil.
Never had any bother with my 261 M-tronic in the 5 years I've had it.
I read about the bearing problems after I'd got it but have always followed the user manual advice (as recommended on here I think) to slacken the chain off after extended periods of work...attached...

 

Plus I take the opportunity every year 18 months to replace the bearing. They aren't that expensive compared to new drums etc.

 

Bob

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The stuff about greasing the bearing and slackening the chain is, IMHO, bollocks designed to distract from the fact that Stihl ballsed up somewhere. As mentioned, any grease will be gone within the first couple of minutes use. So no danger of overgreasing! As for slackening the chain- it'll only heat up and expand that much if you have no oil there. It's never been an issue on any saw I've used, unless the oiler was faulty or the sprocket badly worn.  I always put my saws away after use, and when I come to get them again- perfect chain tension. Just as I left them!

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Cheers@Bob_z_l, I’ll keep this in mind, glad to hear you’ve had no problems with your saw. My problem now is, is it the crank, case or clutch part that was wrong? Got an m-tronic crank, two cases one m-tronic damaged and one clean unknown 261 case, the clutch assy will be all new. It doesn’t really matter, I’ll build it and run what I brung.

 

I know what your saying@doobin, but I’ll heed any advice. Stihl went wrong somewhere, and a answer was never brought forward.

 

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10 hours ago, Heavy Oil Saw said:

Another one I read was that the bearing housings weren’t cast true in the casings, causing the crank to run out of harmonic balance as such, trashing the clutch bearing and in the process the crank end.

Wish Stihl just came out with it.

I never over lube, or try not to, big waste as most lube in any application gets thrown out, and splatters everywhere.

That sounds feasible and Stihl should have been more open about it. Yes, the bearing just needs tiny amount of grease as it ends up in the drum.

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1 hour ago, doobin said:

The stuff about greasing the bearing and slackening the chain is, IMHO, bollocks designed to distract from the fact that Stihl ballsed up somewhere. As mentioned, any grease will be gone within the first couple of minutes use. So no danger of overgreasing! As for slackening the chain- it'll only heat up and expand that much if you have no oil there. It's never been an issue on any saw I've used, unless the oiler was faulty or the sprocket badly worn.  I always put my saws away after use, and when I come to get them again- perfect chain tension. Just as I left them!

This .

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The Mtronic ones are always OK, It is the ones that had the conventional carb that were suspect. I have written off some tidy machines in the past through crank damage.

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On 21/01/2020 at 18:05, spudulike said:

The Mtronic ones are always OK, It is the ones that had the conventional carb that were suspect. I have written off some tidy machines in the past through crank damage.

im pretty sure our one which had a crank fail was autotune, not 100% mind.

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im pretty sure our one which had a crank fail was autotune, not 100% mind.

I’ll just have to see. I’m just building the saw, not sure where I’ll run it yet, so I’m not all that worried as it won’t be my bread and butter if it fails.

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22 hours ago, carlos said:

im pretty sure our one which had a crank fail was autotune, not 100% mind.

Unlikely unless it was caused by something else but stand to be corrected:cursing:

A good option is to whip the side cover and bar off every two months and give it the wobble test, changing the bearing if it does wobble.....put your thumb and finger on opposite sides of the drum and try to wobble the thing. If it wobbles 3-5mm on the edge then it is well on its way. If you put a new drum and bearing on your saw, just remember how it feels - only works if the crank isn't damaged though.

Also, if you put the chain brake on and the machine stalls...investigate the issue as the bearing has probably collapsed.

Edited by spudulike
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