Question: The clutch bearing failed on my Stihl 021

[John from Cle Elum]

The clutch bearing failed on my Stihl 021. I found none of the bearings or the cage. Probably somewhere in the chips near my wood pile. Bad news is the crankshaft is kind of rough under the bearing. Is there way to repair it? A sleave or something of that nature? I can probably dress it up somewhat with some 400 or 1000grit wet or dry sandpaper and just reassembly everything. I like the saw, it has been reliable, it runs great, has good compression and is the right size for the wood I usually cut. I am not looking forward to replacing the crank. Stihl parts are expensive and somewhat hard to find. Any suggestions?

 

[J D]

I'd check the saw over pretty thoroughly before ordering anything... you will have gotten rather lucky if it's chewed up the contents of that bearing & spat it out without munching something else along the way. Need to be sure there aren't any bits still hiding in there too!
As far as the crank goes, if it's still straight & the bearing is still a firm fit I'd put it back together with some bearing retaining compound & see how it goes

 

[Vintage Engine Repairs]

Clutch drum needle bearing? Just remove any burrs / high spots on the crankshaft and put a new needle bearing on - grease it well. You may need a new clutch drum if the hole is wallowed or damaged. Post some pictures of both so we can help you with more certainty with the direction offered.

 

[J D]

^ or that... I probably should've been paying a bit more attention

 

[John from Cle Elum]

It is a needle bearing. I am not sure how tolerant they are to a surface which not perfectly smooth. I am going to look for a sleeve bearing. It probably won't last long but it may be worth a try. I think got all the pieces out of the assembly.

 

[ericm979]

It is a needle bearing. I am not sure how tolerant they are to a surface which not perfectly smooth.

They don't like it.

The clutch bearing only turns when the clutch is disengaged, i.e. the chain is not moving but the engine is running. It's not ever under much load. Which is why it gets away with little lube.

I'd smooth off the high spots as suggested. Grease it a little- too much and the grease will end up in the clutch. And keep an eye on it. Try to avoid revving the saw with the brake engaged, which would put the most load on it. Yea I know we all try to avoid that but sometimes people forget the brake is on or rev the saw when they start it with the brake on. Depending on the damage to the crank it might last a while. Worst case you'll have to replace the crank.

 

[slimbo3006]

Had to replace one on a 260 not long ago. pretty cheap and easy to do. luckily this one had not seized yet or damaged the crank surface. As vintage said, be sure to check the drum. it might have wallowed the center out of it as well. Make sure you grease the new bearing well, but not so much that it slings off and gets on the clutch surface. I gotten into the habit of checking mine whenever I take the side off to change chains or flip bars. Good piece of mind...

 

[John from Cle Elum]

I understand your point about the bearing not actually turning when the clutch is engaged. I often let it idle when not actually cutting anything. I found a sleeve bearing on Amazon that will fit. I will try that first see if it lasts. It can't make anything worse.

 

[stihltech]

Smooth the crank, replace the bearing and grease it. Then re grease it every dozen chains or so. You will not have an issue. Pretty common occurrence.

 

[John from Cle Elum]

Thanks for the advice stihltech. Grease the needle bearing and periodically re-grease.

 

[SteveSr]

Thanks for the advice stihltech. Grease the needle bearing and periodically re-grease.

First of all...




Second, If you do decide to use the original clutch drum... check the clutch drum for "wobble" after assembly. This can allow interference with the brake band or plastic main housing, and/or oil pump drive. It may also allow the clutch drum to cut into the oil gallery.

The hardening on the crank is only a few thousandths thick and once this is gone the shaft will wear pretty fast. You may already be past this point. Early in the 261 production Stihl laid a bunch of crankshafts that had no or bad crankshaft hardening with a high failure rate. The proper fix is to replace bad parts with new (or good used)

I recently had a 251 where the owner left the saw in part throttle with the chain brake on. Burned up the main housing, clutch drum, and galled the crankshaft. While searching online for a replacement I saw many "used" supposedly good engines with galled crankshafts.

My advice would be to find a bad (scored) engine but with a good crankshaft and fix it right.

 

[John from Cle Elum]

I plan to clean up the surface as much as possible and reassemble with a new drum and bearing. If the bearing fails again then I will replace the crank. I am not looking forward to another project.