troutfisher
Addicted to ArboristSite
So, what mix were you running?
Frustrations Rebuilding a 440
- Thread starter litefoot
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Lakeside53
Stihl Wrenching
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Lakeside53
Stihl Wrenching
I've seen many bearing cages where the plastic was cracked, but it hadn't let go. Any time the cylidner is pulled I try to get my ottoscope down into the crankcase area and find a focus point... just so I can see the cages in the small window the crank affords. Rotating the crank many tmes while pushing on the cage with a probe will often give you a complete view.
Even though Stihl says metal cage have lower bearing life in saws than PA, I like metal cages, at least the riveted type.
Even though Stihl says metal cage have lower bearing life in saws than PA, I like metal cages, at least the riveted type.
litefoot
Addicted to ArboristSite
I know everyone is getting tired of all the split case photos these last few days, but here's evidence that you guys were right about the plastic bearing cages.
Here's the two sides after I picked the remnants of plastic out.
And here's a photo of some of the pieces left over. The plastic on the FW side was completely gone.
Used the Lakeside angle iron method to split the case. Way easier than I imagined. Thanks, Andy!
Here's the two sides after I picked the remnants of plastic out.
And here's a photo of some of the pieces left over. The plastic on the FW side was completely gone.
Used the Lakeside angle iron method to split the case. Way easier than I imagined. Thanks, Andy!
litefoot
Addicted to ArboristSite
A couple of questions:
I noticed that the flywheel had been rubbing against the ign module contacts. Would the missing bearing cages create a wobble in the FW side of the crank?
My IPL shows the following for replacement parts for the MS440:
Gasket/Seal Kit: 1128 007 1050
FW-Side Bearing: 9503 003 0346
Clutch-Side Bearing: 9523 003 4275
Does that look right, and can anyone give me MSRP on these? My local dealer believes in MSRP + 15% or more. Thanks a bunch!
I noticed that the flywheel had been rubbing against the ign module contacts. Would the missing bearing cages create a wobble in the FW side of the crank?
My IPL shows the following for replacement parts for the MS440:
Gasket/Seal Kit: 1128 007 1050
FW-Side Bearing: 9503 003 0346
Clutch-Side Bearing: 9523 003 4275
Does that look right, and can anyone give me MSRP on these? My local dealer believes in MSRP + 15% or more. Thanks a bunch!
PES+
Addicted to ArboristSite
Yes
When the cages let go the flywheel hits the laminations of the coil.
When the cages let go the flywheel hits the laminations of the coil.
Absoultely. That's how I initially found the problem on that 064.
litefoot
Addicted to ArboristSite
Thanks PES+, here's what the coil looks like. Doesn't look like there's enough damage to worry about.
Next, I've got to order parts and remove/replace the bearings. Another adventure, but it looks like there's plenty of good reading/info to be found here.
Next, I've got to order parts and remove/replace the bearings. Another adventure, but it looks like there's plenty of good reading/info to be found here.
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Would a later 028 Super have the same issues of the bearing cages becoming brittle due to straight gas overheating? I am rebuilding one that looks to be very low hours, but had a toasted piston and you could smell the stale straight gas in the tank. This is a side adjust model, likely a very late one.
Does this constitute an attenmpt to hijack a thread? I don't mean to.... seems related. I never thought there would be plastic bearing cages in a saw. or bakelite or whatever composite it is....
Does this constitute an attenmpt to hijack a thread? I don't mean to.... seems related. I never thought there would be plastic bearing cages in a saw. or bakelite or whatever composite it is....
litefoot
Addicted to ArboristSite
Good question. I'm not sure how far back the use of plastic bearing cages goes. But as you can see, Brad and I both noted contact between the FW and the ign module. Maybe that will give you a clue to the condition of the bearing without tearing down the saw.
Lakeside53
Stihl Wrenching
litefoot: The mashed ends on the ignition can be a problem - the laminations are actually insulated from each other to stop eddy current losses. Best way to know to try it though.
teachergirl: No saw is immune to cage failure. Age, heat and gas additives seem to affect some of the plastic (nylon) cages but in general they have lower friction and less ball wear. The riveted steel cages don't fail as easily, but don't have as long a life in the lower ends, particualry in high reving saws. The pressed steel cages that are spot welded suck... Never put these in if you use generic bearings.
teachergirl: No saw is immune to cage failure. Age, heat and gas additives seem to affect some of the plastic (nylon) cages but in general they have lower friction and less ball wear. The riveted steel cages don't fail as easily, but don't have as long a life in the lower ends, particualry in high reving saws. The pressed steel cages that are spot welded suck... Never put these in if you use generic bearings.
Ouch. I have never been to Sweden, nor do I own any Swedish saws. I definitely have never consulted a Swedish physician at a gender identity clinic.....
Thanks for the info. I always thought saw bearings were all metal, kind of like motorcycle main and rod bearings. The nylon is surprising to me, given the elasticity and heat deformation of nylon climbing ropes. I'm sure it is a different type of nylon, though.
litefoot
Addicted to ArboristSite
Follow-up and more problems
Well, I replaced the bearings and oil seals and gasket on the 440 following the service manual and tips from all you good folks here at AS. I then pressure/vac tested the saw. Both failed.
Just so you know, I bent up one of the circlips, so I tested w/o the piston (jug bolted down over the connecting rod) until I can pick up a circlip. Cylinder head screws and case screws were torqued to spec. The spark plug is tight and the decomp appears to be sealing well. And the intake and exhaust test seals appear to be solid.
The gauge drops from 7 psi to 0 psi in about 1.5 minutes, so it's a bad (audible) leak. But without removing the FW and clutch, it's kind of hard to identify. My guess is the clutch-side seal because I hear a faint "bubbling" on that side.
One caveat, I diverged from standard procedure with the seals. When I picked up the seal/gasket kit from the dealer, he stated that two-stroke on the rubber would be fine (instead of grease). Would that cause a sealing problem, or is that more for long-term durability? I was very careful to not seat the seals past flush with the bearing races.
Well, I replaced the bearings and oil seals and gasket on the 440 following the service manual and tips from all you good folks here at AS. I then pressure/vac tested the saw. Both failed.
Just so you know, I bent up one of the circlips, so I tested w/o the piston (jug bolted down over the connecting rod) until I can pick up a circlip. Cylinder head screws and case screws were torqued to spec. The spark plug is tight and the decomp appears to be sealing well. And the intake and exhaust test seals appear to be solid.
The gauge drops from 7 psi to 0 psi in about 1.5 minutes, so it's a bad (audible) leak. But without removing the FW and clutch, it's kind of hard to identify. My guess is the clutch-side seal because I hear a faint "bubbling" on that side.
One caveat, I diverged from standard procedure with the seals. When I picked up the seal/gasket kit from the dealer, he stated that two-stroke on the rubber would be fine (instead of grease). Would that cause a sealing problem, or is that more for long-term durability? I was very careful to not seat the seals past flush with the bearing races.
I always use 2-stroke oil on new seals. That's what will lube them for the rest of their lives.
2000ssm6
Stihl User
I know you said you had everything tight but can you pin point the leak? Maybe pump it up and spray some water/soap mix in the questionable areas, any leak will show with bubbles.
volks-man
Arboristsite.com Spooner
silly question(?) can the crank develope a groove from the seal?
i know you said you had a low hour saw but could there have been a little grooving?
litefoot
Addicted to ArboristSite
Thanks, Brad. That makes me feel a little better.
2K, I haven't removed the FW or clutch yet to check. But I will. Thanks.
Volks,
Didn't notice any grooves, but that might be worth checking again.
Martinm210
ArboristSite Operative
Glad you got it all apart, you'll be happy when you put the new bearings and seals in. You'r problem could have been leaking case seals, but replacing them is a good way to make sure that doesn't happen again anytime soon.
The crank bearings are around $50 for both OEM, plus you'll need a gasket set for another $20 or so and you'll be in busines.
The crank bearings are around $50 for both OEM, plus you'll need a gasket set for another $20 or so and you'll be in busines.
Yeah, you won't know until you uncover those seals.
litefoot
Addicted to ArboristSite
Glad you got it all apart, you'll be happy when you put the new bearings and seals in. You'r problem could have been leaking case seals, but replacing them is a good way to make sure that doesn't happen again anytime soon.
The crank bearings are around $50 for both OEM, plus you'll need a gasket set for another $20 or so and you'll be in busines.
Sorry, Martin. I probably wasn't clear in my description. I already replaced the bearings, seals and gasket. I was pressure/vac testing my work.
