Sthil FS85 clutch frozen (long post)

Old 11-17-03, 10:48 PM
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Sthil FS85 clutch frozen (long post)

Hi, I have a Sthil FS-85 bush cutter and the other when I was trimming a hedge (had a hedge trimmer attachment on) the clutch was frozen in the "on" position. Even with the engine in idling, the clutch would not dissenage.

After I finished that job, I put the normal "line trimmer" head back on and still, had the same problem. pulling on the starter cord would spin the head (even if you pulled very lightly, not hard enough to start the engine).

With one person holding the head and the other pulling on the starting cord (spark plug disconnected), you can feel the clutch slip. There is a "slight" resistance (so the clutch is just catching slightly).

Now, few weeks before this happened, I did change the flywheel (with an original flywheel). A screw came loose from the muffler and droped into the flywheel. It wedged in and broke a few fins. After changing the flywheel, we cleaned the the clutch pack + clutch bell (that cup/drum like thing) with some brake cleaner (the repair manual said to de-grease these parts). After re-assembly it worked fine for few weeks.

The other night I took the engine off again. The clutch pack came out of the the clutch bell smoothly, and I could not see anything wrong. There was a little bit of surface rust on the clutch bell (supprised me, cause I would expect it to be very shinny from the clutch rubbing against it).. i cleaned it off the best I could with some rubbing alchol and there was no change, clutch still "frozen".

I'm kinda lost right now. I do have a brand new FS-85 that i'm currently using but am very hesitant to take that appart to swap parts (don't touch what aint broken). the new FS-85 has absolutely NO resistance on the head when you turn the engine over. the clutch is competely free..
Old 11-17-03, 11:16 PM
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Hello JonneyBoy!

It sounds like you may have a washer missing or in the wrong place on the clutch. Disassemble it far enough to see the clutch. Is it touching the bell on the outside edges of the clutch weights? If so, there is a problem with the clutch itself. If not, it is probably hitting inbetween the bell and the clutch...they should not be jammed against each other. I think you will find that the small thin washer that goes on the crankshaft before threading the clutch on is missing.

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