Re: Change belts on SM

Posted by john d on February 17, 2007 at 17:20:58 from (69.130.183.218):

In Reply to: Change belts on SM posted by Soldner on February 17, 2007 at 16:39:28:

Okay, you're in for a treat. It's really simple, but you'll need some common tools, a large supply of PATIENCE, and possibly some choice words to say in moments of frustration.

If the belt is already broken and off the tractor, move ahead one space. If the old belt is still on the tractor, cut it off now.

I find it easier to do most of the work from the left side of the tractor. Suit yourself. The belt rides in a pulley on the front of the water pump. That pulley has a moveable front sheave, that threads onto the hub. Threading it closer to the water pump tightens the belt.

The pulley has two raised square "bosses" that stick out on the front edge of the sheave. One of those has a setscrew in it that is held in place by a locknut. The locknut is loosened with a 9/16 or 5/8 socket, I can't remember which. Once the locknut is loosened, the setscrew can be loosened with a screwdriver. I recommend taking the setscrew and locknut completely out. Put them where you WON'T lose them!

At this point, squirt some good penetrating oil into that setscrew hole. I like PB Blaster, but I've gotten them loose with less. You’ll notice that the setscrew was lined up with a slot or groove in the threads on the pulley hub. If you're lucky, you'll see some of the penetrating oil start seeping out into that groove.

If you have a small wire brush, start cleaning the threads in front of the pulley. Penetrating oil may help. I like to use some spray carburetor cleaner to help remove the grime that's accumulated there over the last few years. Those belts sometimes last 20 years or more, so there's probably a lot of dirt in the threads, and some of it has worked its way into the threads inside the pulley sheave.

When you think the threads are looking pretty good, turn the assembly 180 degrees, and you find another raised portion on that sheave that does NOT have a setscrew. Put a drift pin, large punch, or even a big screwdriver against it and hit it with a hammer. Work from first one side, then the other until you get that pulley sheave to move a little. Keep adding penetrating oil, keep tapping it, and eventually it WILL begin to turn. Once it starts moving - either direction - you're on your way.

Keep working at it, and suddenly you'll find you can move it by hand. When it's really clean, you can spin it on those threads. Above all, RESIST the temptation to get a bigger hammer and bash the *&^%$#@ out of it! You'll break the hub, and replacing that assembly is more work and several more $$ than replacing a belt.

When things are loose and clean, loop the new belt over the fan, onto the pulley, and around the crankshaft pulley. New belts are stiff, and have to be twisted a little to go between the fan and radiator. I suggest wearing gloves for this part of the task, as the fan shroud may have some sharp edges.

Once the belt is in place, it is tightened by threading the movable pulley sheave toward the water pump. A little oil on those threads is a good idea. The belt does not have to be extremely tight. Line up the set screw hole with a groove on the hub; install the screw, then the locknut.

After you've run the tractor several hours, it will take only a few minutes to tighten the belt some more if needed. Once you've done one of these, the second one will take half the time, or less. Unless the generator belt looks pristine, I'd replace it at the same time.

Good luck, and let us know how it went!

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