Things You'll Need
Pair of pliers
New mower deck belt
Since the drive belt on your Craftsman DYS 4500 riding mower is subjected to abrasion from flying grit and debris, you need to fit a replacement from time to time before the belt snaps. Save unexpected down-time by inspecting the belt regularly for signs of wear. Look for frayed edges, signs of burning, and cracks on the inner "vee" section where it meets the pulleys. In addition, if you hear a squealing noise coming from under the tractor and the mower blades start hesitating, it's time to remove the deck and install a new belt.
Drive the tractor onto a smooth level surface. Engage the parking brake, switch off the engine and remove the ignition key.
Move the attachment clutch switch to the "Disengage" position.
Push the mower lift lever forward to its lowest position.
Locate the spring-loaded belt tension rod lying fore and aft on the upper left of the mower deck. This is a 1/2 inch diameter rod stretching from the back of the deck to the front; it is held in place by an open C-shaped inward facing locking bracket a few inches from the front of the mower deck.
Grip the front of the belt tension rod firmly, push down slightly and move the front of the rod an inch or so toward the center of the mower deck to free it from the locking bracket. Raise the rod to the upright position slowly while maintaining a firm grip and downward pressure; this will prevent the rod suddenly flipping up against spring tension.
Roll the worn mower drive belt off the electric clutch pulley attached to the PTO shaft on the back of the engine.
Disconnect the front link leading from the front of the mower deck to the attaching point on the chassis situated on the right of the electric clutch. Remove the hairpin clip and washer from the front link by pilling the clip out with a pair of pliers.
Go to the right of the mower. Remove the hairpin clip and washer securing the lift arm to the chassis lift link and slide the lift link off the suspension arm. Go to the left of the mower and disconnect the left-hand suspension arm the same way. CAUTION: Have a helper maintain a firm grip on the spring-loaded lift lever while disconnecting the suspension arms to prevent the lift lever from suddenly snapping backward.
Move to the right of the mower deck. Disconnect the anti-sway bar running through the two transmission brackets on the rear of the deck. Remove the hairpin clip and washer from the end of the anti-sway bar protruding through the right transmission bracket. Pull the mower to the right until the anti-sway bar falls from the bracket.
Turn the tractor steering wheel all the way to the left and slide the mower out from under the right of side the tractor.
Remove the right and left belt guards covering the mower spindle pulleys by undoing the securing screws with a nut driver.
Take a snapshot of the belt configuration with a camera phone or digital camera to serve as a reference while replacing the drive belt.
Remove the worn belt from all the pulleys; the belt will be slack at this stage. Rout the new belt over the pulleys and into the grooves by following the configuration shown in the snapshot taken earlier. Replace both belt guards and loop the loose front of the belt forward in preparation to connecting it to the electric clutch pulley.
Reinstall the anti-sway bar back onto the right side of the mower deck. Pivot the bar upward and maneuver the deck to line up the anti-sway bar with the hole in the right-hand transmission bracket. Insert the bar in the hole and secure it with the washer and hairpin clip removed earlier.
Ensure that the right and left suspension arms are pointing forward. Check to see that the front wheels are still pointing all the way to the left and slide the mower back under the tractor.
Line up the holes on each suspension arm with the right and left lift link ends in turn, and push the hole in the suspension arm over the lift link. Secure the suspension arms to the ends of the lift link with the hairpin clips and washers removed earlier.
Reconnect the front link by reversing the procedure carried out in Step 7.
Slip the loose looped end of the new belt over the electric clutch pulley. Go to the left of the deck. Grasp the end of the now upright spring-loaded belt tension rod, push the rod forward and downward to the horizontal position and secure the rod by hooking it into the C-shaped locking bracket.
Inspect the entire length of the belt to ensure that it's seated properly in all the relevant pulley grooves. Reach under the deck and move one of the mower blades in a clockwise direction to see that it moves freely as a final check for a correctly seated belt.
Wear safety glasses and heavy gloves while working under the tractor and changing the mower deck belt.