Clutch-side crankshaft bearing not turning (MS361)

[fletcher969]

Hi all,

I'm doing an MS361 rebuild due to a couple of air leaks. One was in the cylinder base gasket, the other was on the clutch-side oil seal. I replaced the oil seals, and I matched the depth of the original seals; however, I noticed after the fact that the clutch side crankshaft bearing isn't turning (i.e. the balls don't move when the shaft is rotated like they do on the flywheel side). The shaft turns easily, there is no play, and there are no signs of prior heat damage to the saft or bearing. The rubber portion of the seal is about 2mm below the clip groove (again, right where the previous seal was seated), and it isn't bulged out (i.e. it's fitting properly), so it appears to be installed correctly, and not too deeply seated that it would be butted against the bearing (and from what I recall, I'd have to bury the seal pretty deep to hit the bearing on the clutch side).

Was the bearing acting this way prior to the new seal? I couldn't tell you. I only checked the play in the crankshaft, and I checked to make sure it was turning easily without symptoms of damage. I never thought to check to make sure the bearing balls were turning inside their tracks.

Anybody have any ideas, or alternatively, is there anything I might try to manually turn the bearing, or free it up?

Thanks.

 

[Jacob J.]

If the crank is turning and the rollers (balls) are not turning with it, then the bearing has "spun" on the shaft, meaning the interference fit is too loose. You either need new main bearings or you need to swap the crank out or both.

 

[axlr8]

Try rotating the crank back and forth and see if there may be something lodged under the bearing balls. Otherwise, im willing to bet you went a hair too far with the crank seals.

If you have split the case and put new bearings in, and this happens, I have had good luck "setting the crank" with a brass hammer.. Hold the crank case in the left hand, hit the end of the crank lightly with the hammer. Do both sides, this sometimes help free the crank from pressure it may have from the cases being pulled together.

On NOS bearings or OEMs I have had some with stale oil that has hardened and needs to be cleaned out before they will roll nicely. A few shots of a brake and parts cleaner, or some premixed fuel and they are good. Just be sure to re oil upon assembly.

 

[fletcher969]

If the crank is turning and the rollers (balls) are not turning with it, then the bearing has "spun" on the shaft, meaning the interference fit is too loose. You either need new main bearings or you need to swap the crank out or both.

And I was hoping somebody would respond that the rollers were stuck somehow, and suggest ways to dislodge them. Well, if your assessment is true, my rebuild is done until next year as my budget must now focus on Christmas. I should probably remove my painting tape so I can see if the inner race is moving or not.

 

[Mad Professor]

How can you see the bearings with the seals installed?

 

[Jacob J.]

And I was hoping somebody would respond that the rollers were stuck somehow, and suggest ways to dislodge them. Well, if your assessment is true, my rebuild is done until next year as my budget must now focus on Christmas. I should probably remove my painting tape so I can see if the inner race is moving or not.

If the inner race is turning with the crankshaft, but the balls are not rolling, that's still a weird scenario. Like Mad Professor points out- it would be difficult to see the bearing in operation with the seal in place, so maybe what you're seeing is playing a trick on you. It could be that the bearing cage is broken, and so the balls aren't moving because of that.

I've worked on many a 361 that I had to find a different crank for, because the shoulder of the PTO side of the crank wasn't a tight fit in a new bearing. Some guys use a liquid adhesive like Loctite 660 to remedy that.

 

[fletcher969]

Try rotating the crank back and forth and see if there may be something lodged under the bearing balls. Otherwise, im willing to bet you went a hair too far with the crank seals.

If you have split the case and put new bearings in, and this happens, I have had good luck "setting the crank" with a brass hammer.. Hold the crank case in the left hand, hit the end of the crank lightly with the hammer. Do both sides, this sometimes help free the crank from pressure it may have from the cases being pulled together.

On NOS bearings or OEMs I have had some with stale oil that has hardened and needs to be cleaned out before they will roll nicely. A few shots of a brake and parts cleaner, or some premixed fuel and they are good. Just be sure to re oil upon assembly.

I've rotated the shaft back and forth plenty hoping the bearing would start to turn, but it hasn't. I also soaked it in WD40 for most of a day, but that had no effect. I thought about taking a small screwdriver or something else I could use to push the rollers, but I thought better of that, figuring I'd only damage something. I'll try hitting it with some brake cleaner, and I'll slosh some premix around in there to see if something frees up. I'll also find something plastic I can use to prod the rollers into action.

As stated previously, I installed the seals to the same position as the old ones, so I can't imagine I'm butted against the bearing. If in fact it is in too far, then so was the previous seal, and I can't imagine I ran the saw for 2 years with a crankshaft bearing not turning without something burning up, or at least making some noise. The bearing not turning might explain why the seal began leaking, but again, after 2 years? I may end up having to split the case, and if so, I'll remove the oil seal before anything else, and check the bearing for proper movement before proceeding. At this point I'd be happy if the seal is butted against the bearing.

I never split the case, so I can't imagine the case is part of the problem; however, I'll try what you suggest regarding the crankshaft if splitting the case is my only alternative.

 

[fletcher969]

How can you see the bearings with the seals installed?

I have the saw apart (i.e. cylinder removed), so I can see them pretty clearly when the counter weights aren't in the way. Enough to see that the flywheel side rollers are moving, and the clutch side rollers are not.

 

[fletcher969]

If the inner race is turning with the crankshaft, but the balls are not rolling, that's still a weird scenario. Like Mad Professor points out- it would be difficult to see the bearing in operation with the seal in place, so maybe what you're seeing is playing a trick on you. It could be that the bearing cage is broken, and so the balls aren't moving because of that.

I've worked on many a 361 that I had to find a different crank for, because the shoulder of the PTO side of the crank wasn't a tight fit in a new bearing. Some guys use a liquid adhesive like Loctite 660 to remedy that.

I've got the crankcase taped shut with a second coat of paint that has another 12 hours of drying, but as soon as I can handle it without putting my fingerprints it it, I'm going to remove the tape to see if the inner race is moving.

One thing I did notice I didn't expect was that I could see the rollers on the inside of the crankcase (sitting behind a solid ring between the races), but on the oil seal side it appeared to be completely solid/sealed (i.e. I couldn't see the rollers/balls). Is that normal, or is something amiss?

Locktite 660 might be a cheap (and temporary?) fix until I can get more involved with this thing, but I'd have to split the case to apply it anyway, correct?

 

[Chainsaw Jim]

I'm with Jacob...The bearing and likely the crank is roached.
I wouldn't be surprised if when the saw got hot the crank and bearing swelled up enough to bind, causing the outer bearing track to spin in the case.

 

[HarleyT]

Sounds like you got some debris in there when you did the first job.

 

[Big_Wood]

loctite 620 unfortunately for you it requires disassembly to apply i just did a 385 i had to loctite the bearing in the case and loctite the shaft in the inner race. with a new bearing they were press fit but i wasn't willing to risk it happening again. i don't need it to come apart again. i just need it to work til the saw bites the dust.

 

[fletcher969]

If the crank is turning and the rollers (balls) are not turning with it, then the bearing has "spun" on the shaft, meaning the interference fit is too loose. You either need new main bearings or you need to swap the crank out or both.

I finally was able to check, and the inner bearing race isn't turning. I also checked to see if the rollers will move if prodded (via the ring which encases them), and they do. Mind you, not super easily, but that could be because I'm introducing an action that normally doesn't move them (and a lateral force at that) versus the inner race doing so. I can always check the bearing's overall condition once the crank is out...eventually. In any event, it appears to be as you describe: inteference fit is too loose.