chain keeps spinning at idle

[pbtree]

its a clutch tom trees

What I would eliminate first...

 

[chieftechtksaws]

another vote for clutch

Does it spin constantly while idling? Or is it just after making a cut the chain spins slowly for a few seconds and quits. The easiest way to check the clutch springs is to use a tachometer. The clutch shouldn't engage until around 3,600 RPMs or somewhere near there.

another vote for clutch

Does it spin constantly while idling? Or is it just after making a cut the chain spins slowly for a few seconds and quits. The easiest way to check the clutch springs is to use a tachometer. The clutch shouldn't engage until around 3,600 RPMs or somewhere near there.

My 044 is doing the above^^ where it only spins at idle after making a cut. It does not do this for the first several minutes after start up, but starts doing this when warm. It's an old saw that I just got from a friend. I did some work to it to get it running and it cuts great, just having the spinning chain at idle problem. My first worry is that it's an airleak somewhere, but to be honest when the chain does spin at idle, it doesn't really sound like it's revving any higher which argues against an air leak, I would think. Any ideas?

 

[Aknutter]

Did you try adjusting the idle?
If not that p/v testing. Might have an air leak.

 

[Old2stroke]

Check the clutch drum bearing. With the engine stopped and the chain off, does the drum spin freely?

Any sign of melted things around the clutch? Overheating the clutch can weaken the springs, allowing the clutch to engage at lower speed.

 

[chieftechtksaws]

Drum does spin freely when off. I took the clutch off, and this is what I see. I can't tell if this is just caked dirt and bar oil or whether that's oil/gas accumulating from a leaking crank seal. Anyway I'll probably end up pressure vacuum testing it soon. Thanks guys!

 

[Aknutter]

If you take the oiler gear off (should pull straight off shaft) there is a bushing that rides the crank, take bushing out , inspect seal .take a pick and post

 

[Aknutter]

I would also take the two covers off around the clutch and clean the crap out. Those two covers are cheap if you want to replace them. Brake band might have crap under not allowing full release of drum when disengaged. I would then look at the clutch for worn out springs and worn out shoes (checking the spring holes).

 

[chieftechtksaws]

Here's a picture of the crank seal with the bushing removed, not the best pic I suppose..fortunately there doesn't seem to be any play or rocking of the crank when i jiggle it, so hopefully the bearing is good. Clutch looks beat to hell, with deep grooves where the springs seat, so either way clutch needs replaced, but I'm still wondering why the problem only occurs after saw is warmed up. I'd think if it were bad clutch or springs it would be a constant problem on startup. Any thoughts?

 

[Aknutter]

How does the seal feel?
Post more pics ...
Clutch
Drum inside angle to see clutch ride
Sprocket
Angle pick of seal / crank

 

[chieftechtksaws]

Last picture is a picture of the seal. It was very brittle, to the point where i inserted a qtip to clean off the gunk (which im pretty sure is fuel mixture), and it broke little pieces of black rubber off the seal. The spacer that seats on the inside of the seal also seems to insert without feeling very tight. I also posted a picture of the clutch washer/plate thing that looks like it has had fuel mixture spill on it, and has been casting it off centripetally. Basically I'm almost certain this seal is bad. I ordered the oem seal for the clutch side and the flywheel side, as I figure it's probably **** too... Clutch looks beat, there are some grooves in that thing for sure. I'm going to install these crank seals and run it with the tach nearby. If the problem continues and the chain is spinning at idle, i'll check the rpms. If they haven't increased from baseline, I'll know it's the clutch, if the rpms are increased ill assume I have a leak and spray carb cleaner everywhere until I find it or p/v test it.

 

[Aknutter]

Few more picture, take the muffler cover off 4 screws and let's look at the piston for condition. Rotate motor and look at piston top, rings, skirt, inside to the other side of

 

[Aknutter]

Well I'd say you are going to need pto crank seal. Especially if it's brittle, and chipped. Seal has been leaking causing the grey/black soot. Need to see what piston looks like. Clutch is a bit worn, possibly change.

 

[chieftechtksaws]

Piston actually looks immaculate, I had muffler off the other day. Actually, it's appearance is the only reason I'm putting any money into a 30 year old saw haha

 

[Aknutter]

Then change the crank seals and clutch/ drum she'll run another 30

 

[Aknutter]

Buy the Stihl OEM seals...

 

[chieftechtksaws]

Done did. Had to get them off ebay. Kind of disappointed, stihl dealers said they were "obsolete"

 

[stihltech]

Obsolete? Funny, I am still putting them in.

 

[chieftechtksaws]

Yea like, wtf? Anyway, any tips for pulling the old seals and placing the new ones? I saw some cool tricks using stacks of washers and a nut to slowly and evenly press it in. Think I prefer that method over tapping it in with a socket. Any ideas in getting it out with minimal tools? Most of my tools are back home

 

[Tomos770]

Or this....


Or two spax screws (self treading wood screw) and then you pull it out with 2 pliers (watch out when you tread them in....that you will not damage bearing cage!)

 

[Tomos770]