357XP seized and crank rotation feels 'rough'

[J P]

First, I'm not a saw mechanic and this is the first time I've attempted this much work on one. Any help and advise much appreciated. Just trying to avoid having to buy a new saw. I'm 1/8th into a 15 acre project that I was hoping to get mostly done this spring.

My saw had what I thought was a lean seizure. I was getting near the end of my cutting for the day and noticed the saw seemed to be running lean-like. Then it had a couple brief episodes of really high revs so I quit sawing for the day. Next day, thinking I'd try to find the problem I found it had seized. I put oil in the cylinder and waited a while but I couldn't get the flywheel to turn with a wrench so I tapped on the pawl bolt heads with a block of wood and it freed up. Compression tested 78psi. Pressure test seemed to indicate a leak at the intake which seemed to make sense. I now have the cylinder off and to my untrained inexperienced eye the cylinder and the piston really don't look too bad other than the ring seems stuck in the groove.

Now my bigger concern is that when I rotate the crankshaft it doesn't turn smoothly. It should shouldn't it? I don't feel any slop but it has a lumpy feel about every 1/4" of rotation of the flywheel and I'm guessing that's from a bad crank end bearing. Is there anything else that would cause it to feel that way? Could I have boogered a bearing by tapping on the pawl bolts? Am I looking at having to work on the bottom end of this thing too? That is a daunting thought. Unfortunately I didn't check the crank seals when I pressure tested. Should I put the cylinder back on and test again or is it pooched anyway?

Saw is 10 years old, almost to the week, and hadn't had more than maybe 5hrs/year, tops, on it until the current project. It's been trouble free until now and other than basic maintenance hasn't had anything else done to it. I'm aware (now) that these saws had known issues with the intake system and I had planned on replacing/upgrading the partition and clamp, piston, ring, and rod top bearing. Figured on doing the impulse and fuel lines while I'm at it.

Thanks in advance for any advise/help. First post here but have learned a lot browsing around for some time.

 

[roostersgt]

Sounds like bearing(s) toast to me. Looks like a total rebuild with case splitting, gaskets, seals, bearings, piston/rings and hopefully you can save the cylinder and the case didn't suffer any damage when bearings went..

 

[HiOctane]

If you hit the crank,it could be only the flywheel rubbing against the case or the base of cyl.Look at it.If it appears to be that,then "hit" the crank on clutch side lightly to "center" everything using a small brass block and hammer.Or bearings are done.

 

[sunfish]

Very good saw and well worth fixing! Maybe the cylinder can be cleaned up and then a new piston & ring. Not sure about the crank bearings, but isn't that big a deal to replace them and the seals. I'd use all Husky parts if it were mine. Oh and make sure you fix the air leak that caused all this.

 

[brokenbudget]

chances are it's the fried piston giving you that 'rough' rotation.

 

[blsnelling]

"Lump" sounds like the magnets going past the coil. Remove the coil and try again. I'm assuming you already have the P&C removed?

 

[J P]

If you hit the crank,it could be only the flywheel rubbing against the case or the base of cyl.Look at it.If it appears to be that,then "hit" the crank on clutch side lightly to "center" everything using a small brass block and hammer.Or bearings are done.

OK, I gave the crank a few whacks and not much changed. I'll take the FW off.

Very good saw and well worth fixing! Maybe the cylinder can be cleaned up and then a new piston & ring. Not sure about the crank bearings, but isn't that big a deal to replace them and the seals. I'd use all Husky parts if it were mine. Oh and make sure you fix the air leak that caused all this.

Yeah, I like the saw, it's been just right for what I use it for. I think the cylinder if fine and will clean up no problem.

chances are it's the fried piston giving you that 'rough' rotation.

Cylinder is off.

"Lump" sounds like the magnets going past the coil. Remove the coil and try again. I'm assuming you already have the P&C removed?

Cylinder is removed. 'Lumps' are throughout the whole 360 FW rotation. I'll take the coil and FW off.


I'm trying to think if there is some correlation between the seizure and a crank bearing failure. Bugs me to not know what caused a problem before fixing stuff. Could the high revving do that? I wouldn't guess so for such a short duration. Looks like I'll be getting to know this saw inside out.

Thanks all for the feedback.

 

[nmurph]

Bearing usually fail from foreign materials finding there way to the bottom of the saw. The bearings on the bottom of the rod can fail for the same reasons as well as over-revving for extended periods or from detonation caused by poor fuel.

Make sure nothing is dragging on the flywheel. From there, if the "feel" is still there, a splitting of the crankcase is the next step.

 

[J P]

Took the flywheel off and there was a lot of crud packed behind it. Much smoother now so I guess that's all it was. Odd that it was making the rotation feel bumpy. Maybe there was a crudball rolling around. I'm going to leave it at that and just deal with the top end.

What's a good way to clean the crankcase, rinse with fuel mix followed by some compressed air?

 

[nmurph]

You can use water, degreaser, and a brush. Don't worry about the water harming anything. Just make sure to hose the crankcase out well when you are finished scrubbing, then soak the bottom-end with WD40. Make sure you get plenty into the bearings. Then dump it and reassemble, and then run it until it is good and hot. I know it sounds strange, but it is safe. I just did two like this yesterday.

 

[phillipmc]

All the crude behind the flywheel could of taken a seal out causing the lean condition also. Probably a good idea to replace the seals being you already have it torn down that far. (cheap insurance) Then clean up everything, including the cylinder replace piston and ring. Run a pressure/vac test and be back to work again. Also make sure you inspect the intake system well for splits/cracks to avoid another lean out. Next time might not be so lucky.

 

[turtle561]

if it has one, replace the plastic snap-type carb clamp with a metal screw type (36mm-stihl has them). like this:Bailey's - Hose Clip for Stihl 34mm x 7mm
here's how to do it :
http://www.arboristsite.com/attachments/chainsaw/225336d1329852375-359-partition-mod-pdf

 

[timmcat]

By any chance was it a heated handle saw? The magnets on the inside of the flywheel tend to give that lumpy feel when there is no piston or cylinder on the saw to create drag.

 

[blsnelling]

I would go ahead and pull both crank seals before flushing the crankcase, especially since their condition is suspect already.

 

[J P]

Thanks y'all for the advise on the seals. Closer look at the FW side seal and I can see that it's been rubbed. The FW has a little sharp burr on it right there. I don't know if the burr was actually touching the seal or more likely catching and dragging crud around. I'll see if the local dealer has any seals or order some. The shop manual I have shows a "special" tool for fitting the seals. Is that necessary or can I just use a socket? I haven't seen the clutch side yet. While I'm waiting for parts ... and finish making some kind of clutch removal tool ... I think I'll put the cylinder back on and re-check the press/vac of the existing seals ... just so's I know.

timmcat, no heated handle.

turtle561, I was planning on using a metal screw clamp for a 372. Somewhere I read that would work.