This mower has a 42" deck, two blades, one belt (#144200). To install belt, bear in mind the idler pulleys are flat sided which means the flat side of the belt contacts these …pulleys, while the V-type pulleys receive the V-side of the belt..
First, make sure the deck is connected to the mower at mounting points - two in front, the sway bar in the rear to keep the deck from rubbing the back-right tire, and the left side height adjustment hangar. Leave the right hangar and engagement rod disconnected to install the belt..
Lower the deck all the way. From the right side, slide the belt through to the left side, push the belt under the left blade pulley cover and drop the V-belt into the pulley, pull it taught to keep it firmly in the pulley (not underneath it). Feed the right-hand portion of the belt counter-clockwise around the left idler (flat) pulley straight up to the engine pulley, come around engine pulley straight back to the right (flat) idler pulley going counter-clockwise towards the right blade pulley. At this point, the left side of the belt should be coming straight across the rear of the deck from the left blade pulley to the right blade pulley. Take the belt off the engine pulley, shove the belt underneath the right blade pulley cover and drop the V-belt into the top pulley, pull it taught to keep it firmly on the pulley (not underneath it)..
Before installing the belt back onto the drive pulley at the engine, check twice to see that the belt is NOT on the outside of the thin metal belt keepers located at the idler pulleys. Make very sure the flat side of the belt is contacting the idler pulleys and not the wrong side of the belt keepers or else the belt will shred in about 30 seconds of operation. The belt should be parallel to the deck without going over or under any obstructions. (straight from point to point)..
Now is a good time to install the belt engagement rod that is barely visible on the right side of the mower up a little higher from the deck (Move the engagement lever to see the connecting hole for the rod.) Make sure the engagement lever is in the down position (disengaged) before putting the belt on the engine pulley. The belt should slip fairly easily around the engine-pulley yet still have just enough tension to keep it from falling off the pulley. Now, connect the deck to the right hangar. .
With the engine OFF, engage the deck belt to check tension (about Â½"of movement), and double check the idlers and belt keepers and overall alignment. With deck all the way down, check the angle from the drive pulley to the idlers. The less angle the better to avoid excessive edge wear on the belt. .
Side-note: To save wear on the thin aluminum drive pulley, raise the deck, engage deck at low RPM, then raise to max RPM for best cutting, then lower deck. Also, to save wear on the aluminum drive pulley, leave the drive belt engaged as much as possible and instead use the automatic transmission for braking, reversing, and going forward. It is designed for this type of use. If I'm not mistaken, this tranny uses straight 30W MOTOR OIL for hydraulic fluid and should not need servicing, theoretically, according to the manual. (MORE)