stihl 261 and 362 crank problems

[fordf150]

I have talked to local stihl dealer and he says they are having some problems but that he is not sure exactly what they are at this point. I have had 6 261's with the crank wore where the clutch bearing rides on it and a couple 362's with the same problem along with a 362 that the big end rod bearing failed on.362 with rod bearing failure has a perfect piston and cylinder. I dug the 362 out from under the bench to take a picture. it has been hanging around the shop for 6 months and decided to add it in to my questions about the 261. Anyone else seeing these issues or do I pass these all off as isolated cases of operator error.

 

[dl5205]

I believe this is the first I have heard of this.

 

[Mastermind]

50:1 strikes again.

 

[MustangMike]

What gas, 2 cycle oil, and mix ratio do you use?

 

[dall]

I did a couple 362s and found the connecting rod bearing bad I have 2 junk cranks in my junk pile and also another from a 311 I know when the 362 is running good it sips the fuel but at what costs would richening the oil help it out on these motors

 

[2dogs]

2 years ago the crew I was working on had both an MS261 and MS362 lose a crank within a week of brand new. The dealer replaced both saws. Later in the year a new MS440 had a piston score the cylinder. All happened on 50:1 Ultra with premium pump gas. Stihl said the crank failures were common at the time but didnt say anything else. The dealer told to use 41/2 gallons of gas rather than 5 for the mix. I was running my own mix using Opti 2 and never had a problem. I now own the 440 (that Nathan blew up) and the 261.

 

[fordf150]

50:1 stihl oil. That might explain thecouple bad rod bearings. I tried to get them to do 40:1 but stihl says 50:1 so they won't do it.

 

[Mastermind]

The big end bearings are built the same on Stihl, Husky, Dolmar, Echo, etc. I have no doubt that all these manufacturers use proper heat treating and machining processes when building their products. Some may be a little undersized for the displacement (the 390XP comes to mind)......but with plenty of oil.......I rarely see crank failures.

 

[lone wolf]

The big end bearings are built the same on Stihl, Husky, Dolmar, Echo, etc. I have no doubt that all these manufacturers use proper heat treating and machining processes when building their products. Some may be a little undersized for the displacement (the 390XP comes to mind)......but with plenty of oil.......I rarely see crank failures.

Looked dry in the pic the OP posted.

 

[sunfish]

That clutch bearing needs a little lube also... Just sayin.

 

[MustangMike]

50:1 stihl oil. That might explain thecouple bad rod bearings. I tried to get them to do 40:1 but stihl says 50:1 so they won't do it.

Full synthetic?

 

[fordf150]

the crank has been wiped off so I could take measurements to see if the discoloration was just playing tricks on me. .004 thousands variation on one and .010 on the other at the worst spot. Rod bearing could all be in the way they run their saws and the 50:1 that they use. Just added it to the mix since I was asking about crank problems and I have seen the same clutch bearing wear on those too. it is stihl oil but which version I don't know. these saws are coming from a power line trimming crew so they are HARD on equipment but I don't think I should be seeing that kind of wear on saws that have only been in service anywhere from 6 months to 2 yrs. no problems out of their 361's or 201T's.

 

[Mastermind]

If Stihl's QC is slipping like everyone else's......

Heat treating could be not as good.

 

[nmurph]

There were some early 261 clutch bearing problems on saws across the pond.

 

[dl5205]

But... But... There's this guy, on the Interwebz, That runs AMSOIL @ 100:1. He says His saws last FOREVAR!

OIL Thread!

Get Some!

 

[MustangMike]

I know they recommend full synthetic and mid level octane on the newer saws. Used to run my 044 on non synthetic 2 cycle oil and regular gas for years w/o any problems. I think some of the newer saws may have tighter clearances and benefit from the full synthetic, while the older saws may keep running just fine on the non synthetic. Often "crews" do not use the higher cost synthetic oil.

Also, the newer saws likely run leaner to meet emissions, which results in them running hotter. Synthetic oil withstands higher temps much better.

Not sure that I am correct, but those are my thoughts.

 

[fordf150]

just talked to local dealer again and they claim it is just how they are using the saws.they are seeing the exact same failures from other crews bringing saws in there. I buy that and that was my original diagnoses. high revs with no load/inadequate oil. New guys running wfo all the time and using saws to trim brush instead using the proper tool. I cant come up with a reason for the bearing surface deteriorating except for poor quality cranks.

 

[Mastermind]

Long idle periods could hurt the crank, drum area......but was else?

 

[TreeTangler]

Long idle periods could hurt the crank, drum area......but was else?

I'm curious as to why you think this. I'm not debating it in any way, just wondering why you think so. Less mix running through the case at idle?

 

[Mastermind]

I'm talking about the clutch bearing........not the rod bearing.