300 belt replacement

The 300 guy · Jan 1, 2013

Does anyone have a service manual reference (with pictures) to installing new water pump and generator belts? It has been many moons since I have installed then. I know you have to turn the outer pulley half to remove and tighten the belts. I have both service manuals for the engine and chassis but neither of them show this repair.

Hugh McKinney · Jan 1, 2013

I can tell you that if you are installing a new water pump, and surely new belts with it, all you have to do is unscrew the four (?) bolts that hold the water pump in place. You can then remove the water pump assembly with the belts. Once you have it off, I strongly suggest you thoroughly clean and lubricate, with graphite, the threads on the outer sheave (half of pulley) on the water pump/fan/pulley assembly. It's not as hard doing it as it is to describe it. Mainly, when you re-install your new pump and belts, get you a 36 inch length of 5/16 all-thread to stick from one side of the fan shroud to the other side, to prevent the fan from rotating when you are trying to tighten the fan belt. And of course, be sure that you have the generator belt IN PLACE BEFORE you put on the fan belt. I don't have a 300, I have a 450, but I don't think that it's much different. Good Luck.

Zachary Hoyt · Jan 2, 2013

The generator belt has to be removed from the generator by unbolting the third arm of the bracket and pushing the generator toward the water pump to slacken the belt. It can be moved over the fan one blade at a time and allowed to dangle from the crankshaft pulley. I have never changed the fan belt on a 300 but I imagine that once the belt is loosened it could be moved off the crank pulley and moved over the fan one blade at at time.
Zach

mkirsch · Jan 2, 2013

Clean up the threads on the water pump hub as best you can and lubricate them with your favorite penetrating oil.

There's a nut and set screw on the outer sheave of the water pump pulley. Find it and remove it.

Place a punch at an angle against one of the raised points on the outer sheave, and tap with a hammer to cause the sheave to rotate counter-clockwise on the pump hub. After a few taps the sheave should be loose enough to rotate by hand.

Even after the sheave is totally loose, the belt will be a tight squeeze over the crankshaft pulley, but it will come off. It will come off over the fan blades too, just do one blade at a time.

The easiest way to get the generator belt off is like Zach says, but it should have a similar pulley setup to the water pump.

Anonymous-0 · Jan 2, 2013

If you use a hammer to loosen the sheave be carefull. Have seen guys bust them with hammer. When I replace mine I use a spanner wrench less chance of damage.

300 belt replacement

The 300 guy

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Hugh McKinney

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Zachary Hoyt

Well-known Member

mkirsch

Well-known Member

Anonymous-0

Well-known Member

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