Lawn Mower Not Self-Propelling (Causes and Solutions)
Article by Mark Trotta
Unless you have to cut grass uphill or cut grass in a ditch, you may not need or appreciate a self-propelled lawn mower. But for those of us that do, they are true work savers.
Front Wheel Drive vs Rear Wheel Drive Lawn Mowers
Self-propelled mowers can be either front-wheel drive or rear-wheel drive. The mower in this article is a Craftsman front-drive "EZ Walk" with a Briggs & Stratton engine.
Front wheel drive pulls rather than pushes. Instead of having to use your body to push the mower, lift on the handle, and the mower pulls itself. The self-propel function is off until you pull the handle, so you only use it when you need to.
Self Propelled Lawn Mower Problems
While cutting the lawn one summer day, the self-propel function on the mower stopped working. After 10 minutes of manually pushing the mower in the hot summer sun, I stopped and accessed the situation.
There are several possible reasons why the self-propel function stops working. These include the control cable out of adjustment, worn or broken drive belt, drive pulley problem, or bad transmission motor.
The self-propel control cable runs from the mower handle down to a small "transmission" motor by the front left wheel. The cable pushes the transmission motor against the drive belt, which engages the drive pulley and turns the drive wheel.
Over time, the cable will stretch and may require adjustment to compensate for the slack. This is the most common reason the self-propel function stops working.
Shop: Control Cable
If the control cable is damaged, it needs to be replaced.
The cable for a Craftsman EZ Walk mower is 532176556 (should be a sticker on the back of the mower with part numbers.) If you can't find a part number, chances are, if your mower is 21" Craftsman with a rear bag, this will fit. If you need Craftsman part number 420561, the 532176556 is slightly shorter but may work.
A stretched or broken V-belt also prevents a walk-behind mower from moving. Check the belt for wear and damage. Tighten if needed, or replace if worn or broken.
A less common reason for failure is the transmission motor itself. On the Craftsman front-drive mower, the motor sits in a cut-out on the deck near the front wheels.
Less likely, but other possible causes for a lawn mower that doesn't self propel are a broken deck tray or broken wheel.
In my case, it was the drive pulley that turns the gear-case shaft to propel the front wheels. The original 20+ year-old pulley had rusted out and the belt slipped off the bottom. I was able to pry the belt back on the pulley and continue cutting the lawn, but slipped off again several minutes later.
Drive Pulley Replacement
I ordered an original equipment pulley on Amazon. This particular pulley is a Husqvarna part #2443262. Both Sears and Husqvarna pulleys are the same, and it has many lawn mower applications.
Dimensions of the pulley are 2.60" x 2.10" x 1.00"
Shop: Lawn Mower Drive Pulley
This particular pulley is a genuine Husqvarna replacement, part number 532443262.
Replacing the pulley required holding the shaft from underneath with a pair of vice-grips. This was to prevent the shaft from turning while removing the top pulley bolt.