Poulan Micro xxv crankshaft play

[Rob22]

Happy new year, new poster here with a question on crankshaft radial wobble/runout on a poulan micro.

I picked up the saw cheap on CL. It starts with some difficulty and cuts but it intermittently loses power and has untunable/runaway idle. The saw seems pretty well used judging from wear of the housing where the starter rope lands. Posts here suggest looking at the crankshaft seals and it was easy enough stripping back to inspect them. While doing the teardown I notice that I can wobble the crankshaft a pretty good amount, enough for me to hear a faint rattle. If I push the crankshaft side to side I create 0.005in total runout. Attached pics show the measurements.

What's typical for a saw...I've worked on autos as a hobby but it's been awhile since I worked on small engines. FWIW I'm not married to the saw, damn thing burned my hand the other day

Thanks
Rob

 

[82F100SWB]

Those saws use flat roller bearings that slide on the crank. There are thrust washers that slide on first, but almost every one I've had had a similar amount of play.

 

[Rob22]

Thanks for the reply and advice. I ended up splitting the case and replacing bearings.

I've run into a problem though and could use advice. I just reassembled the halves and now the crankshaft is really tight. It takes a lot of force pushing on the balancer to get it to rotate. I can't rotate it at all if i grasp the crankshaft, whereas before I could spin it easily. Should it be this tight?

 

[Goinwheelin]

I think there needs to be a gasket in there between the case halves.
Just a guess as haven’t dug into a micro xxv yet.

 

[RED-85-Z51]

I think there needs to be a gasket in there between the case halves.
Just a guess as haven’t dug into a micro xxv yet.

Nah just sealer.

Try using a dead blow on both ends of the crank to release any preload

Sent from my LM-G820 using Tapatalk

 

[Goinwheelin]

Nah just sealer.

Try using a dead blow on both ends of the crank to release any preload

Sent from my LM-G820 using Tapatalk

Good to know for when I dig into mine. Thank you.

 

[Rob22]

I think I got it figured out, when I installed the bearings I didn't get them flush with the crankcase inside surface and this was pinching the crankshaft at the sides.

I went back in and measured, the inside face of each bearing was sitting about 0.003in proud relative to the crankcase surface. I pulled each bearing slightly more outboard so that the inner face of each bearing sat flush/subflush relative to the crankcase inner surface.

The deadblow is a good idea, I would have tried but had already started back in.

Next time I will dry fit the halves together with crankshaft before I put the sealant on.

There's a lot less radial slop in the crank than before. I'm not sure if it's resulting from the bearings or the seals, or both.

During reassembly I noticed that the reed valve wasn't seating completely on the intake so I flipped it.

Hopefully this takes care of the air leak that I'm suspecting and I'll be able to get this thing to idle. Thanks for the help.

 

[Muzzleblastm38]

its nice shape you are lucky
mine i replace bad fuel line and carb kit
its strong for the size

 

[Muzzleblastm38]

under the handle where is the read valve is it a gasket or silicone

 

[Rob22]

Mine had cork gasket between the plastic housing holding the reed valve and the crankcase. I was thinking about replacing the gasket by cutting a new one or using hondabond but it was in pretty good shape so I reused it.

 

[canadian175]

One time i used a bacon package, worked fine.it was thick as gasget paper.also used it in crankcase halfs of an old sach 18h.p. snowmobile engine.
Canadien bacon,worked fine.those were the days.