Stihl 441 pilot bearing problem

[Mikeb]

Have a Stihl 441 with 36" bar, 3/8 .050. During our teams deployment to Georgia, we went through 3 pilot bearings in 1 week. Chain tension was correct, pilot bearings lubed daily. Saw ran 8 to 10 hours a day clearing tornado damaged trees, cutting mostly pine. Anyone run into this kind of bearing failure? Replacement bearing were from Stihl, bar was also a Stihl bar

 

[jmssaws]

Chain is to tight
How's it oil that 36"? I bet it oils it about as good as it runs it.

 

[Mikeb]

Oils bar and chain quite good, runs great in the pine we were cutting. Thank you for the prompt response

 

[HarleyT]

Are you talking about the "Sprocket bearing"?
Do you always fuss with it?

 

[Mikeb]

Are you talking about the "Sprocket bearing"?
Do you always fuss with it?

Yes, don't normally mess with bearing but after replacing the first bearing, we started watching it closely

 

[ChoppyChoppy]

Are you letting the saw idle a bunch? That is tough on the clutch bearing.

 

[HarleyT]

Yeah, a few sawmills around here used to let their saws idle most of the time, they also had saw damage on the bottoms of the saw, where it contacted the ground.

 

[Mikeb]

Yeah, a few sawmills around here used to let their saws idle most of the time, they also had saw damage on the bottoms of the saw, where it contacted the ground.

Never considered idling could be the problem but I don't think we idle in excess

 

[HarleyT]

That is when the bearing sees use. When cutting, the bearing is not being used.
What kind of lube did you use?

 

[alexcagle]

I'm kind of with @jmssaws on this one.
*
A 441 can pull a 36" bar, but it's oiler output may not be suited for extended longer bar use. Plus it may have something to do with the dryness in that type of wood.
Or perhaps your oil pump is just not working correctly.
It's not hard to imagine something simple like a oil pump worm gear tang slipping, but that would eventually cause the oil pump to completely stop working.
*
It also could be that when the first one went bad, it either damaged the crank or the sprocket surface at the microscopic level.
It doesn't take much roughness to create plastic race melting heat.
*
What are you lubing the bearing with?
*
Ask your Stihl dealer for the correct recommended Stihl sprocket lube.
Have your operator goop it up daily, or even twice daily, and see if it helps.
Also, how much side to side play is there on the sprocket?
If it's got too much, it may be that the lube you are using is flowing out to quickly when it get heated up from extended cutting. If that's the case, it may be time for a new rim sprocket drum.
Sometimes a thin washer can help with slop, and keep that grease sponging dust out too.
*
Does the saw in question sit idling
much?
As you probably know, the oil pump only pumps when the sprocket is turning.
This means how ever much oil or grease is on the sprocket bearing when you set it down to idle is all that it has to work with.
*
If nothing helps, then you probably need a 661 or an 880 to pull that 36" bar for day in and day out use.
*

 

[HarleyT]

If he is talking about the sprocket bearing, what does that have to do with the oiler output?

 

[Mikeb]

I use Stihl superlube FS on the pilot bearing. Oiler is working great, fuel tank empty, oil tank empty. Oiler turned wide open. I understand this bar length is not recommended for this saw, we normally run a 28" bar on this saw. After reading all comments here,I am going back to the 28" bar, correct chain tension and closely monitor chainsaw idle time. Thanks for all the prompt and very helpful replies.

 

[alexcagle]

If he is talking about the sprocket bearing, what does that have to do with the oiler output?

*
I know the oiler doesn't necessarily oil the sprocket bearing, but being in close proximity to a warm oily chain when the chain stops usually leads to some residual oil to seaping down into the sprocket and that bearing.

 

[HarleyT]

*
I know the oiler doesn't necessarily oil the sprocket bearing, but being in close proximity to a warm oily chain when the chain stops usually leads to some residual oil to seaping down into the sprocket and that bearing.

Nahhh...

 

[jmssaws]

I've never greased one of them and cut timber for years,I can think of 2 going bad.

 

[lone wolf]

OP are you power washing the saws?

 

[hedge hog]

Sound like clutch drum is warped
Try a new drum


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[TreeswingerPerth]

Sound like clutch drum is warped
Try a new drum


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+ one , that's what I thought .

 

[Mikeb]

+ one , that's what I thought .

As an update, found plastic from drum bearing cage melted onto oiler worm gear causing it to strip. Remedy to this whole situation, new oil pump and worm gear, new drive drum and needle bearing, 28" bar. Great lesson learned, thank you all for your help

 

[hedge hog]

Us a bigger pump
At least a 460 R pump assembly or a piston
I have 441 R pump and to my liking it is only good to a 25" bar



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