How to Replace a Lawn Mower Belt on a Front-Drive, Self-Propelled Mower

These instructions show you how to replace a lawn mower belt on a particular model.  Keep in mind that the steps may vary slightly for your MTD lawn mower model.  If you feel uncomfortable replacing your push mower belt or performing any other maintenance, take your machine to an authorized service center.

Before starting your project, refer to the "Replacement Parts" section of your MTD lawn mower manual to find the part number for your machine's belt.  Make sure you have the correct replacement lawn mower belt.

Step 1: Put the push lawn mower on an even surface

Before you start the process of changing your push mower belt, place your machine on a flat, level surface.

Step 2: Disconnect the spark plug wire

Remove the spark plug wire to prevent accidental starting while you replace the lawn mower belt.

Step 3: Check the fuel tank

Make sure your push lawn mower's fuel tank contains little to no fuel. If tank is full, use the Arnold Siphon Pump to pump the fuel into an appropriate container. Then, tighten the fuel cap.

Step 4: Check the oil dipstick

Make sure the oil dipstick is tight.

Step 5: Remove the front drive cover

Remove the two shoulder screws securing the front drive cover to the deck of your push lawn mower.  Press in on the sides of the front drive cover to release the tabs that secure it to the height-adjuster brackets.  Remove the front drive cover from the push lawn mower and set it aside.

Step 6: Remove the push mower belt

Loosen the screw holding the belt tension spring to the transmission. As you twist it, the tension on the belt will be released.  Push the transmission, pivoting it toward the engine, and slide the belt off the transmission pulley.

Step 7: Put the push lawn mower on its side

Tip the push lawn mower on its side with the air filter up.

Step 8: Make sure your hands are protected

When removing mower blades, protect your hands with a pair of heavy gloves or use a heavy rag to hold the blade.

Step 9: Take off the blade bolt and bell support

Remove the blade bolt and bell support, which secure the blade and blade adapter to the engine crankshaft. Set them aside.

Step 10: Take off the blade and blade adaptor

Remove the blade and blade adapter from the crankshaft. Set them aside.

Step 11: Remove the engine baffle

Locate the baffle bracket that secures the engine baffle to the push lawn mower's deck housing. Press in on the tab on the engine baffle to release it from the baffle bracket. Remove the engine baffle and set it side.

Step 12: Remove the push mower belt

Slide the belt off the engine pulley, and pull it through the opening in the deck housing.

Step 13: Replace the lawn mower belt

Install the new push mower belt through the opening in the deck housing.  Place the push mower belt in the engine pulley.  While pulling the push mower belt from the transmission, slide it over the transmission pulley.  Make sure the belt is fully seated in both mower pulleys.

Step 14: Reattach the engine baffle

Reattach the engine baffle in the reverse order.

Step 15:  Install the blade adapter

Lubricate the engine crankshaft and the inner surface of the blade adapter with a very light coating of oil.  Slide the blade adapter onto the crankshaft, aligning it with the key way.  Push the blade adapter until it bottoms out on the crankshaft.

Step 16: Put the blade on the adapter

Place the blade on the blade adapter.  The wing tips should be up and the side of the blade with the word "bottom" or the part number on it should be facing you.

Step 17:  Align the blade with the adapter

Make sure the blade is aligned and seated on the blade adapter flanges.

Step 18: Put the blade bell support on the top of the blade

Place the blade bell support on top of the blade and align the notches on the blade bell support with the small holes in the blade.

Step 19:  Check your work

Turn the mower back over and make sure the belt is still seated in the transmission pulley. Tighten the screw you loosened earlier to secure the belt tension spring to the transmission.

Step 20: Install the front drive cover

Install the front drive cover and secure it with the two shoulder screws.

Step 21: Replace the spark plug wire

Reconnect the spark plug wire to the spark plug.

Step 22: Clean up

Wipe up any fuel or oil spilled while you were replacing the push mower belt.

Step 23: Start the mower

Fill the fuel tank with fuel and start your push lawn mower. Note: Sometimes after having the push lawn mower tilted, the engine will smoke when you start it. This should stop after a short period of run time.