Stihl 261 loss of power

[jamesmcsparron]

Hello yins.

I have a Stihl 261 M-tronic, which I bought 2014 ish. It was a really powerful saw for it's size until at the start of this year the oil pump failed. A bloody badly put-together setup in my opinion. Looked like it was glued together with toothpaste! But. The bar was heated several times from lack of lube before I'd realised that it actually was the pump and not dirt blocking the flow. I replaced the pump and ever since the saw has lost a very noticeable amount of power. I'm not sure if there is a connection between the heating of the bar and this loss of power. I hope I haven't melted some shnife inside the saw from the bar heating. I reset the tuning as described by Stihl for M-tronic carbs but still sad power output.
Has anyone any notion of what may have happened to the power?
Thanks.

 

[bwalker]

Hello yins.

I have a Stihl 261 M-tronic, which I bought 2014 ish. It was a really powerful saw for it's size until at the start of this year the oil pump failed. A bloody badly put-together setup in my opinion. Looked like it was glued together with toothpaste! But. The bar was heated several times from lack of lube before I'd realised that it actually was the pump and not dirt blocking the flow. I replaced the pump and ever since the saw has lost a very noticeable amount of power. I'm not sure if there is a connection between the heating of the bar and this loss of power. I hope I haven't melted some shnife inside the saw from the bar heating. I reset the tuning as described by Stihl for M-tronic carbs but still sad power output.
Has anyone any notion of what may have happened to the power?
Thanks.

How hot did the bar get?
I suppose if you got it smoke hot you could cause a PTO side crank seal failure. Which could lunch your motor via an air leak.
Does the saw have good compression, have you pulled the muffler and inspected the piston?

 

[ZeroJunk]

Hello yins.

I have a Stihl 261 M-tronic, which I bought 2014 ish. It was a really powerful saw for it's size until at the start of this year the oil pump failed. A bloody badly put-together setup in my opinion. Looked like it was glued together with toothpaste! But. The bar was heated several times from lack of lube before I'd realised that it actually was the pump and not dirt blocking the flow. I replaced the pump and ever since the saw has lost a very noticeable amount of power. I'm not sure if there is a connection between the heating of the bar and this loss of power. I hope I haven't melted some shnife inside the saw from the bar heating. I reset the tuning as described by Stihl for M-tronic carbs but still sad power output.
Has anyone any notion of what may have happened to the power?
Thanks.

Have you tried a different bar and chain ? Or, somehow made sure the lack of lube doesn't have your bar, chain, or both tight.

 

[stihltech]

Time to diagnose. Does it still idle? Does the saw stay up if lifted by the starter handle? Does it start in a few pulls cold 1 hot?
Pull the muffler and see what the piston looks like.
Back to the oiler. Did you clean the inlet hose and oil tank? Is the drive worm OK? Does the drive wire turn on the plastic gear?
Many questions that need answers. But, that is what diagnosis is.

 

[jamesmcsparron]

I replaced the worm. The bar is cleaned regularly. The oiling system appears to be working 100%.The saw did get to quite a high temp whilst the pump wasn't functioning so maybe these crank seals are damaged? There's good compression but I haven't inspected the piston yet. I will today if I get time. I presume I'm looking for scratches on the barrel? Or a damaged ring?