diagnose ms261 failure....pick out new saw

[ogie ogelthorpe]

My ms 261 has gone tango uniform. I've got a 10 acre lot, and 7 is pretty heavily wooded. Was cutting a dead pine when my ms261 sounded like it ran out of gas. Still had some in it, but topped off anyway. After topping off I could not get it to fire. After finishing with dads saw ms 260 I looked into mine. No spark. Tried a new plug. No joy. Bought a new coil. Now I've got spark... but still wont fire. Digging deeper I see a broken ring and scoring from the broken ring. Dad thinks I'm an idiot and didn't use mixed gas. Always 50:1. Always Stihl oil. So.....could the coil have caused some detonation prior to failing, or did my saw ingest something to make it come from together?

After talking to a tree service customer of mine, he suggested the MS361. He's been to my property before when I had an old hickory that died and was in a delicate spot. I ended up using the tree and a hickory my neighbor had that broke off at the same time for floors in my house. So he knows my property and possible usage. He suggested the 361 with a full chisel blade....which sounds a little...aggressive for me.

I'm thinking of buying the meteor kit and rebuilding the 261 just to have around. One other thing I noticed about the 261 is all the bar oil would leak out if it sat for a week or two. It didnt use to do that, so I'm wondering if something came loose, broke, or fell out when replacing the chain.

Really appreciate your insight!

 

[Bob Hedgecutter]

Dad is probably not far off the mark- sounds like a lean failure- or it got very hot and had a melt down.
Chain saws don't have blades- they have bars and chains. Nothing wrong with full chisel chain in clean wood- either it and semi chisel can be filed/ground to be "aggressive", but sharp chain with correctly set depth gauges is safe chain.
Lean mix, lean through an air leak, dull chain working real hard = bye bye piston.

 

[ogie ogelthorpe]

I'm not saying it wasnt a lean failure. In the airplane they have a "red box" and to avoid running lean at high power settings. So I'm aware of the imminent failure. An induction leak is always possible. I just find it odd to have 2 different failures. A failed coil and a broken ring/piston.

 

[Bob Hedgecutter]

Heat of the excessive kind will melt electrical circuits and pistons much the same.
Overheat the coil, they break down pathways inside.
Overheat a piston and it expands until it smears the soft face side all over the cylinder, hangs a ring out of the groove and that catches a port.

 

[thompsoncustom]

Indeed sounds like a lean failure but you also said it's now leaking bar oil? I wonder if the case halfs is were it is leaking bar oil if thats the case than it would also be sucking air further back on the case. Something worth looking into at least.

 

[pioneerguy600]

My ms 261 has gone tango uniform. I've got a 10 acre lot, and 7 is pretty heavily wooded. Was cutting a dead pine when my ms261 sounded like it ran out of gas. Still had some in it, but topped off anyway. After topping off I could not get it to fire. After finishing with dads saw ms 260 I looked into mine. No spark. Tried a new plug. No joy. Bought a new coil. Now I've got spark... but still wont fire. Digging deeper I see a broken ring and scoring from the broken ring. Dad thinks I'm an idiot and didn't use mixed gas. Always 50:1. Always Stihl oil. So.....could the coil have caused some detonation prior to failing, or did my saw ingest something to make it come from together?

After talking to a tree service customer of mine, he suggested the MS361. He's been to my property before when I had an old hickory that died and was in a delicate spot. I ended up using the tree and a hickory my neighbor had that broke off at the same time for floors in my house. So he knows my property and possible usage. He suggested the 361 with a full chisel blade....which sounds a little...aggressive for me.

I'm thinking of buying the meteor kit and rebuilding the 261 just to have around. One other thing I noticed about the 261 is all the bar oil would leak out if it sat for a week or two. It didnt use to do that, so I'm wondering if something came loose, broke, or fell out when replacing the chain.

Really appreciate your insight!

What length of bar were you running on that little saw?

 

[coffeebrk]

Did you pressure/vacuum test this saw?

 

[ogie ogelthorpe]

What length of bar were you running on that little saw?

16"

Did you pressure/vacuum test this saw?

Did not. This happened last fall and just now getting to diagnosing and replacing. Thinking about this more, I wonder if I had an issue with the decompression valve.

 

[ZeroJunk]

When you rebuild the saw pull the clutch off and make sure the clutch drum bearing hasn't failed at some point and let the drum cut in to some of the oiling mechanism. Also, often it is the oil cap that is leaking.

 

[ogie ogelthorpe]

When you rebuild the saw pull the clutch off and make sure the clutch drum bearing hasn't failed at some point and let the drum cut in to some of the oiling mechanism. Also, often it is the oil cap that is leaking.

I appreciate it! I dont believe its the cap as when it was running I could see bar oil get flung off the chain at a pretty good clip. I'll rebuild it at some point. In the meantime I'm going to buy a new saw since I wouldn't mind having a backup and have a handful of trees that need felling. 2 dead pines, a hickory and dad's got a couple oaks.

 

[ZeroJunk]

Well, the MS361 is a good saw. I have one that I rebuilt. They have not been made in a while. So, you would have to find a good used one. The MS362C-M is a great saw, but you are looking at a pile of change new.

 

[ogie ogelthorpe]

Well, the MS361 is a good saw. I have one that I rebuilt. They have not been made in a while. So, you would have to find a good used one. The MS362C-M is a great saw, but you are looking at a pile of change new.

That's what was recommended. 362cm. Not 361. Too many numbers.

 

[stihltech]

Time to get the tools out and diagnose.

 

[Gord404]

rebuilt a 362 a while back- think thats what it was- not a clamshell- anyway what took it out was a stuck open seized decomp- cylinder cleaned up so eliminated the decomp with the thread in plugs and put it back together with a new piston.

 

[Mac&trees]

Dad is probably not far off the mark- sounds like a lean failure- or it got very hot and had a melt down.
Chain saws don't have blades- they have bars and chains. Nothing wrong with full chisel chain in clean wood- either it and semi chisel can be filed/ground to be "aggressive", but sharp chain with correctly set depth gauges is safe chain.
Lean mix, lean through an air leak, dull chain working real hard = bye bye piston.

Is it an mtronic? I like my mix slightly fattened up. I also only use synthetic two stroke. Not a fan of the mtronik or the auto tune. Just my two sense worth.

 

[ogie ogelthorpe]

Is it an mtronic? I like my mix slightly fattened up. I also only use synthetic two stroke. Not a fan of the mtronik or the auto tune. Just my two sense worth.

I thought it was an m tronic but it appears I was misremembering. Haven't had a chance to diagnose. Ended up buying a new 362. One of the big oaks dad needed removed ended up falling the day after I got it.