Recently had my uncle on the riding mower and he hit a branch that slid up into the transmission belt. It got lodged in between and somehow popped the belt off. The belt got chewed up, and in the process broke the plastic transmission fan. I hate paying for people to fix my stuff, so I decided to try it on my own. It wasn't too bad, took me about an hour, and I didn't have any major problems.
Tools you'll need:
3/8" Drive Socket Wrench w/ Socket Set
1/2" Breaker Bar
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Turn off the tractor (Duh), Place the PTO lever to “OFF” position. Move the tractor to a level spot, with plenty of clearance on both sides. Make sure the engine has completely cooled down, as you will have arms and hands very close to parts that are hot. Remove the mowing deck from beneath your tractor. Skip to step 2 if you know how to do this.
I do this by dropping the height down to 2 or 3. There is a handle on either side of the tractor with a black rubber grip. You pull this out to disengage the deck. You’ll want to support the deck with your hand, as it will drop down to the floor. After the deck is down, remove the front linkage bar from the front of the tractor. This simply involves taking the cotter pin out, and unscrewing the nut. Get a few plastic bowls or cups or whatever you have to keep nuts and bolts in. Once this is removed, slide the deck to the “left” side of the tractor (Side without the levers). The PTO cable will still be attached. Remove the cotter pin and and pull the cable up and out of the bracket. Detach the spring from the pulley and set the entire cable assembly out of your way. I hooked it onto the seat spring. Normally, you can just push the deck belt down and off the pulley, but we need to remove the belt guard anyway, so we can do that now. There is (1) bolt and (1) nut to remove the guard. (Get a bowl for those parts!)
Push the belt forward and off the pulley. Now the deck is completely detached. Slide it all the way out and get it out of your way. Now would be a good time to have one of your kids start cleaning it.
On a level surface, raise and block the tractor SAFELY! This is the most critical step of this procedure, as you will be using tools that will cause quite a bit of vibration. I simply lifted the front axle of my mower onto a sturdy wooden table. It gave me about 2 feet of clearance and a sturdy stand. You’ll need enough clearance to get your impact wrench and socket on the engine pulley bolt.
Get the impact wrench out and I believe it was a 16mm IMPACT socket, emphasis on IMPACT socket. Don’t use a regular socket, it may break sending shrapnel into your body. Set the socket on the engine pulley and lay into that sucker, have your hand on the pulley, as it will want to slide down. (Hopefully you have hit the thing with PB blaster for a few days.) Note which direction the spacer on the pulley faces. (Bowl for the parts!) If you forget which direction it faces, have a look at the picture.
Take note of the path the belt takes before you remove it. To get the belt off of one of the idler pulleys, you'll have to remove a small bolt. (Bowl!)
Remove the belt off of the pulleys, except the transmission pulley.
The transmission pulley has a guard all the way around it. You have to remove the pulley and lift it up, to clear the guard. I had to do this anyway, because the fan needed to be replaced. Since my fan was obliterated, I locked onto the plastic with a pair of vice grips, then used my 1/2” socket on the pulley nut. This was not an easy removal. It only took 10 minutes, but I busted quite a few knuckles. Very satisfying when it finally moves though. Once you break it free, lift the pulley up and remove the old belt.
Start the new belt on the engine pulley. Route it over the steering gear towards the rear of the tractor. Install the engine pulley, and hand tighten the bolt.
Route the belt around the transmission pulley and install the pulley and fan back onto the transmission. You’ll have to set the parking brake / cruise control lever to get some slack in the belt and run it around the idler pulleys.
Torque the nut on the transmission pulley down. I’m going to be honest, I have no idea what the torque spec is, so I just got it on there as tight as I could. I found one reference that said the engine pulley bolt should be at 50lbs., but I’m not 100% sure about this. I just made it very snug. You can remove the spark plug and stick some rope in there if the pulley is slipping.
Step 9: Reinstall the small idler pulley bolt that was removed.
Step 10: Reinstall the mower deck.
Step 11: Reinstall the engine pulley guard.
Step 12: Go mow that lawn!