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This may seem like a crazy question, but I have to ask. I have an 04 Yard Machine, model 13A7660G752 with a 20hp Tecumseh engine. It keeps throwing the drive belt off the front pulley. I contacted MTD to find out what I need to remove the pulley and they state the bolt is a 7/16-20X1.25. I crawled under the mower yesterday and it appears that the bolt needs some type of spanner wrench to remove it and the pulley. Can anyone shed some light on what I need to purchase to remove the bolt and pulley? Thanks for your help.

Put the belt back on hold belt tight remove bolt. Better question would be to ask why do you need to remove pulley?

I hold the pulley with a pipe wrench.
Or you can get a bolt to thread into the spark plug hole to stop the engine from turning.


I don't know why you are removing the pulley.

Is the belt old?
Are the belt guides bent or missing around the pulley?

I am going to say that if the pulley is not bent then it is not the reason the belt comes off.

The idler pulley bracket, that tensions the belt, is possibly allowing the idler pulley to be mis-aligned. Belt retainer clips are also sometimes out of place.

If you decide to put a bolt in the spark plug hole to keep the engine from rotating, better get you a new piston located before attempting that because you will surely punch a hole in the piston.

SeniorCitizen said:

The idler pulley bracket, that tensions the belt, is possibly allowing the idler pulley to be mis-aligned. Belt retainer clips are also sometimes out of place. If you decide to put a bolt in the spark plug hole to keep the engine from rotating, better get you a new piston located before attempting that because you will surely punch a hole in the piston.

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They sell a kit that is really just a bolt to hold the piston. There are a few techs on here that use this method. I also thought it would punch a hole in the piston but it does not.

One other way is to put a string in the spark plug hole.

I need to remove the pulley because it is bent and throws the belt off every time I start the mower. I need to know what type of bolt was used besides the one that MTD states is inside holding the pulley on.

The bolt is a 7/16 with a 5/8 hex head. I normally use an impact to remove the bolt. In a perfect world the pulley will then slide off the crankshaft. In reality it will be stuck to the crankshaft and will either need to be driven off, with lots of penetrating oil, or cut off.

Just use a 5/8 socket

I have seen a few that take a 9/16

It is a 5/8 deep socket or regular socket with extension. Select Assembly then Engine Accesories. Number 33
http://www.mtdparts.com/equipment/mtdparts/yard-machines-riding-mower-13a7660g752?tabView=diagrams

Pulled it apart yesterday. There was no bolt holding the pulley on, just rust. Got another pulley and pet it back together correctly. Going to give it a try today on my yard.

Well that explains all the confusion on how to take it off.