Craftsman 42" 917.270610 Drive Belt Keeps Slipping Off

Hi,

I recently bought a Craftsman 917.270610 "as is", and I think the guy had done something to mask a problem with the drive belt.

It worked the first 2 times I mowed my 1/2 acre yard, then the drive belt slipped off. Since then, it will run for between 30 seconds and 2 minutes before slipping off again.

I can take my finger and slip the belt back on, start it back up and mow for 30 seconds or so then it slips off again.

The clutching idler pulley is really loose...I can move it back and forth a little, and can "tilt" it about 25 degrees. Is that the expected behavior? I checked the clutch idler spring, thinking it had fallen off, but it's there.

Any ideas? I'm new to lawn mower repair, so I don't want to spend my whole Saturday replacing the belt and spring only to find out that wasn't the problem in the first place...

The tilting idler pulley is what is probably allowing the belt to come off. Need to find out what is wrong with the pulley, idler arm and get it fixed and that should solve your problem.

ILENGINE said:

The tilting idler pulley is what is probably allowing the belt to come off. Need to find out what is wrong with the pulley, idler arm and get it fixed and that should solve your problem.

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Okay, let me ask the question a different way. My idler pulley is loose and can be bent down about 25 degrees. What are the possible reasons this could happen?

Pktivey said:

Okay, let me ask the question a different way. My idler pulley is loose and can be bent down about 25 degrees. What are the possible reasons this could happen?

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If the location where the idler pulley bracket mounts looks similar to this that could be one reason the pulley doesn't align properly. Take it off and have a look.

SandburRanch said:

If the location where the idler pulley bracket mounts looks similar to this that could be one reason the pulley doesn't align properly. Take it off and have a look.

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Does this picture help? Where the mounting apparatus attaches to the chassis seems really solid...the problem really is that the bracket isn't really attached to the mounting apparatus. It just kind of hangs there.

Notice that the big hole in the bracket is touching the side of the nut, and above the nut is some sort of a washer. Should that nut and washer be on the bottom of the bracket?

Hmmm, could somebody have replaced the old washers with washers that aren't big enough, and they slipped off? That would mean I just have to replace the washers with bigger washers, right??

Pktivey said:

Does this picture help? Where the mounting apparatus attaches to the chassis seems really solid...the problem really is that the bracket isn't really attached to the mounting apparatus. It just kind of hangs there.

Notice that the big hole in the bracket is touching the side of the nut, and above the nut is some sort of a washer. Should that nut and washer be on the bottom of the bracket?

Hmmm, could somebody have replaced the old washers with washers that aren't big enough, and they slipped off? That would mean I just have to replace the washers with bigger washers, right??

Click to expand...

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QUOTE Pktivey: I recently bought a Craftsman 917.270610 "as is", and I think the guy had done something to mask a problem with the drive belt.
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I think you are exactly right.

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From what I can see in your pic that big hole has worn to that size and is egg shaped from spring tension which is common if that is where the bracket pivots. I'm not familiar with that exact set up but I suspect there was never a washer there but only a shouldered bolt and the washer was added to get it to a new home and possibly you are the second owner of that washer. But maybe all isn't lost if you can find a new bracket and shouldered bolt and that old Craftsman will surely appreciate it. Remove the nut ( probably a lock nut ) and see if we are playing ball in the right park.

I have the same machine . Generic belts fall off . A quality Gates belts stays on . One thing is to check the belt guides - l shape brackets- one is missed or not tight enough and moved . . The belt is falling off because it is sloppy and the tractor is bouncing whole moving .