MTD help

[har860]

I have a MTD yard machine - model 660 through 679. It goes into 1st gear for about 30 minutes, then slows down, moves into 2nd gear, mows about 10 minutes then slows down again. I see the belt slip. Would it be the belt or variable speed pulley, or some other problem? Your help would be appreciated.

Thank you,
Harold

 

[SeniorCitizen]

I have a MTD yard machine - model 660 through 679. It goes into 1st gear for about 30 minutes, then slows down, moves into 2nd gear, mows about 10 minutes then slows down again. I see the belt slip. Would it be the belt or variable speed pulley, or some other problem? Your help would be appreciated.

Thank you,
Harold

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That's a nice system when it works but a common problem is for the center section of the variable pulley system to become sticky / dirty and not respond to the pressure change that is initiated by the operator changing speed positions of the selector. If the belts have been slipping, and they usually do when the variable is malfunctioning, the belts are most likely shot. But don't replace those expensive belts until you determine the variable is correct. OEM belts are recommended on that sensitive drive system. People have tried cheaper ill fitting belts with poor results.

I suggest removing all belt tension of both belts or remove the belts from the pulley completely and determine if the mid section pulley of the variable is free to slide up and down. If you move it to the most upward position it should slide back down from its own weight ( that is if the shaft is a vertical system ).

If that center pulley section is free and works as designed, I suggest going a little deeper into the variable and check out the bearings. It may be best if the variable assembly is removed for that.