A self propelled lawn mower makes mowing your lawn much easier by helping you 'push' the mower with a belt and pulley. The lawn mower uses a belt and pulley (connected to the motor) to propel the unit automatically so that you don't have to exert too much force to push it. However, from time to time, the belt may wear out and need to be replaced. Not to fear though, it's an easy DIY job, and this guide will show just how to do it.
Step 1 - Remove the Spark Plug Cap
Just to be safe, you should always remove the cap from the spark plug before working on your lawn mower to keep it from possibly starting while you are working on it.
Step 2 - Remove Belt Cover
On the top of your lawn mower and near the rear wheel, there will usually be a cover on the housing that contains the belt used to propel your mower. Depending on the model you own, you'll need to use a screwdriver or wrench to remove this cover.
Step 3 - Disengage Drive Pulley
If the pulley is engaged, you'll need to release the tension on the belt by using the shifter lever near the top of the handle to disengage it. On some mowers, the belt is engaged with a second handle that is pulled up to the main push handle and uses a spring to engage the pulleys. If your lawn mower is of this type, the pulley will automatically disengage whenever you release the second handle. So, you won't need to worry about this step.
Step 4 - Tilt Lawn Mower on Side
Place a piece of cardboard or plastic on the ground that is large enough to keep your lawn mower from getting too dirty. Then, tilt the mower on its side so that it rests on the cardboard or plastic. When tilting the mower, make sure that the gas tank and filter are facing up and not pressed into the ground.
Step 5 - Remove Old Belt
If you have released the tension on the belt with the handle or shifter, you should be able to remove the belt fairly easily. However, sometimes you may need to use a flat head screwdriver to gently pry the belt off of the pulley. Once you remove the old belt, don't throw it away as you'll need it when you buy a replacement.
Step 6 - Purchase and Install New Belt
Take the old belt with you and purchase a replacement belt at your favorite hardware store or local home improvement center. Once you return home, install the new belt by sliding it over the blade pulley and then the wheel pulley. To do this, you may need to push the wheel pulley toward the engine slightly.
Step 7 - Adjust Tension
Once the new belt is installed, check the tension. If the belt seems to be a little loose, look for a small bolt or nut on the pulley wheel that will let you adjust the position of the wheel pulley. Adjust the tension of the belt as needed.
Step 8 - Turn Mower Upright
Flip the mower so that it is again right side up.
Step 9 - Replace Belt Cover and Spark Plug
Screw or bolt on the belt cover and a place the cap on the spark plug. You should now be able to use your lawn more as you normally would.