Z Pump belt vibration

[netknut]

I have a new Z with 10 hours and the pump belt vibrates considerably at rpms below half throttle, seems to even out at higher rpm. Idler bracket nut has been adjusted to allow various degrees of movement in the bracket without much success although the belt vibration does seem to move from the idler pulley to the other pulleys as the bracket tension is changed. Any suggestions welcome as the dealer is less than helpful.

[mowerconsultant]

The first thing I would look at is the v grooves in the pulleys, there could be a piece of debris in a groove that would cause this to happen, stick, acorn piece, pine cone piece.. etc..etc..
I would then check the belt out for a flat spot.

Pj

[Mickhippy]

I had a little rock get into mine a few weeks ago! Almost shook me off the machine! Belt broke maybe 20hrs later!

[Coastline Lawn]

I had a piece of a stick in one of mine about a week ago. Started vibrating. I shut it off and climbed under the rear and checked the pulleys. Sure enough, small piece of stick was wedged in one of the pump pulleys. Dont run it like that. Nothing good can come from it....

[Sharpcut 1]

There is a different spring you can run with different harmonics that may help.The part #starts with 601, butI can't remember the rest off the top of my head. Your dealer can contact their distributor and they should be able to find the parts bulletien.

[netknut]

Further investigation discovered that the idler bracket is bent. The pulley end of the bracket is bent up enough that the end of the bracket rubs the tractor frame and the edge of the pulley is rubbing on the head of one of the engine mounting bolts!

The belt also appears to be worn considerably.