"New (Genuine J.D.) Belt jumps of LT166 W/48C Deck"

[richsch]

Any Adjustments to fix?

 

[tom3]

First thing I'd do, with motor off reach under there and give the belt a couple good yanks, see that the spring loaded tensioner is moving like it should.

 

[mechanic mark]

http://manuals.deere.com/cceomview/OMM142698_I0/Output/OMM142698_I011.html#40242

see #14 under "installing mower", adjusting mower engagement rod

 

[richsch]

Thanks I will give it a try. Since my original thread I have also found out: If I slowly disengage the mower blades it does not pop off the left pulley. That is with the deck blade engage arm. It seems I have too much (sloppy) slack in the new belt.
Another contributing factor is I am missing the left pulley shield. Could that missing shield cause the belt to jump off the left pulley when quickly disengaging the deck belt? Thanks for your help.

 

[mechanic mark]

Thanks I will give it a try. Since my original thread I have also found out: If I slowly disengage the mower blades it does not pop off the left pulley. That is with the deck blade engage arm. It seems I have too much (sloppy) slack in the new belt.
Another contributing factor is I am missing the left pulley shield. Could that missing shield cause the belt to jump off the left pulley when quickly disengaging the deck belt? Thanks for your help.

yes, very possible.