MTD 21 Single Stage Eats Belts - Snowblower Forum : Snow Blower Forums
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post #1 of 5 Old 01-12-2017, 12:19 PM Thread Starter
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MTD 21 Single Stage Eats Belts

Hi All,

Happy New Year.

I recently purchased a second single stage 21 MTD snowblower 31AS2S1E700 that has a 4 cycle engine.

I noticed something was vibrating on the belt cover so I opened it.

When i opened the BELT cover i noticed the belt had a chew mark and was off the pulley. It slided to the crankshaft pulley side.

I put the belt back and put the belt case cover back however i noticed when pulling the throttle cable; the idler pulley somehow
makes contact with the cover. Is this the one causing the problem?

I am thinking of snow blowing without the cover since i also bought a new belt and same thing happened got chewed off. Something in the pulley
must be extremely wrong for it to eat the belt. I suspect it is the idler pulley or the tension spring because when i press the throttle the snow blower
shakes and rattles it disappears when i engage it in snow.

Has anyone encountered this problem before or had similar issues with a 21 mtd blower?

Last edited by robbiwan; 01-12-2017 at 12:39 PM.
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post #2 of 5 Old 01-12-2017, 12:41 PM
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Does the belt has a lot of play when not engaged? Is this the drive or auger belt?

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post #3 of 5 Old 01-12-2017, 09:10 PM
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A picture of the parts involved is here:

Manual is here:

Did you get it new, or used? If new, take it back where you bought it for repair under warranty.

If used, check the clutch cable that pulls the idler pulley into contact with the belt. Do this cover off, engine off and just get an idea of what's happening and that things travel without sticking or snagging on other things and that nothing is dragging on the belt itself. Verify that the idler pulley is routed correctly on top of the back side of the belt, and that the spring on the idler is not broken. Try watching everything turn with the engine on, keeping fingers, neckties, scarves, fingers, etc out of harms way or course.

Take a look at the alignment of the pulleys to see that they are in the same plane, and that the auger shaft does not have excessive side to side play which would cause misalignment. Check the grooves in the pulleys for rust or roughness that could tear up the belt. Check the springs and position of the idler pulley which should not be hitting the inside of the belt cover.

Also, make sure that you have the proper belt for the machine designed for power equipment. If the previous owner just threw on a belt that seemed to fit, and you bought another one with the same part number, it might not be a belt rated for the kind of demands a snowblower makes on a belt. Belts for cars and furnace motors will not stand up on snowblowers, garden tractors etc.

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Last edited by skutflut; 01-12-2017 at 09:25 PM.
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post #4 of 5 Old 01-12-2017, 09:44 PM
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post #5 of 5 Old 01-13-2017, 10:29 AM
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I have an older mtd single stage so it might not translate to your machine. But I found that on my machine the belt seemed a tad to long to remain tight enough when engaged. I was noticing a bunch of rubber dust under the cover and that the throwing distance was lame.

I went to a slightly shorter industrial belt that's Kevlar coated and performance was improved and the belt hasn't deteriorated like previously.

One issue with the smaller belt is that there is just enough friction around the crank pulley to cause the belt to wrap and whack the cover a bit. Sounds worse then it is, the auger does not spin unless engaged.

I'm not crazy about these MTDs.

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