Lawn mower not self propelling: Common Causes & How to Fix
1Lawn Mower V-Belt
Most Common Solution
Repair Instructions:
The V-belt in your lawn mower is responsible for moving the drive pulleys and, in turn, propelling the mower's wheels. If this belt is worn or broken, it prevents the wheels from turning. So, inspect the V-belt to see if it's damaged. If you discover that the V-belt isn't in good condition, it will need to be replaced
How to Replace Lawn Mower V-Belt
- Disconnect spark plug wire - Locate the spark plug wire and detach it from the spark plug to prevent accidental starting.
- Loosen belt tension - Use pry bar or block of wood to push down on deck or release tensioner to loosen belt.
- Remove old belt - Slip the old V-belt off the pulleys, taking note of the proper routing.
- Inspect pulleys - Check pulleys and bearings, cleaning debris and lubricating as needed.
- Loop new belt - Following old belt routing, slip the new V-belt around the deck drive and blade pulleys.
- Adjust tension - Apply pressure or tighten tensioner to get proper tautness on the new mower belt.
- Check alignment - Confirm belt is centered on pulleys and not twisted or binding.
- Reconnect spark plug wire - Reattach the spark plug wire once the new belt is fully installed.
- Test operation - Start mower engine and engage blades to verify smooth operation with the replaced V-belt.
- Make adjustments - If issues, recheck belt routing, tension and pulley alignment. Replace belt if damaged.
2Lawn Mower Wheel Assembly
Most Common Solution
Repair Instructions:
Your lawn mower's wheel assembly contains a series of gears that mesh with the transmission drive gear. If these gears become worn out, the transmission won't be able to connect with the wheel assembly, preventing the mower from moving. If you find that the gears are indeed worn out, you'll need to replace the entire wheel assembly
How to Replace Lawn Mower Wheel Assembly
- Raise and support mower - Use a jack to safely lift the mower deck and support it with jack stands.
- Remove hardware - Take out the axle bolt, washers and retaining pins that secure the old wheel assembly.
- Detach wheel - Carefully remove the faulty wheel assembly from the deck or mower frame.
- Install new assembly - Slide the replacement wheel onto the axle or mount point, aligning any splines or keys.
- Secure wheel - Reinstall washers and retaining hardware in the original locations and orientations.
- Tighten hardware - Use wrench to tighten the axle bolt or other fasteners to the specified torque.
- Remove supports - Once the new wheel assembly is installed, lower the mower from the jack stands.
- Check tire inflation - Inflate the new tire to the recommended air pressure printed on the sidewall.
- Test operation - Roll mower forward and check for wobbling or issues with the replaced wheel assembly.
- Make adjustments - If problems arise, recheck hardware tightness and realign or balance the new wheel.
3Lawn Mower Drive Pulley
Most Common Solution
Repair Instructions:
The drive pulley in your lawn mower is linked to the engine crankshaft. If this pulley is damaged or broken, it won't be able to enable the transmission to connect with the wheel assembly. As a result, your mower won't move. Therefore, it's important to check the drive pulley for any signs of wear or damage. If you find that the pulley isn't functioning as it should, you'll need to replace it
How to Replace Lawn Mower Drive Pulley
- Disconnect spark plug wire - Locate the spark plug wire and detach it from the spark plug to prevent accidental starting.
- Remove belt - Loosen belt tensioner and slip the drive belt off the old pulley.
- Take off pulley - Use wrench to loosen and remove the pulley retaining bolt and washers.
- Install new pulley - Slide replacement pulley onto drive shaft, aligning any keyways or spline.
- Secure pulley - Thread pulley bolt through center of new pulley and tighten to specified torque.
- Replace belt - Loop drive belt around the new pulley, checking alignment. Apply proper tension.
- Check operation - Spin pulley by hand to ensure smooth rotation and proper belt grip.
- Reconnect spark plug - Reattach the spark plug wire once the new pulley is fully installed.
- Test drive - Start mower engine to verify proper drive speed and engagement with the replaced pulley.
- Make adjustments - If issues arise, recheck pulley alignment, belt tension and torque on mounting bolt.
4Lawn Mower Transmission
Common Solution
Repair Instructions:
The drive belt, connected to the engine crankshaft, powers your lawn mower's transmission, enabling the wheels to turn. To check if the transmission is faulty, watch it while the mower is operating. If the transmission pulley is spinning but the mower's wheels aren't turning, this suggests a problem with the transmission. It's important to note that transmissions can't be repaired. If you find the transmission is defective, you'll need to replace it to get your lawn mower functioning again.
How to Replace Lawn Mower Transmission
- Disconnect spark plug wire - Locate the spark plug wire and detach it from the spark plug to prevent accidental starting.
- Drain oil - Remove the drain plug and drain old oil from the transmission case.
- Detach drive linkage - Remove clevis pins, washers and cotter pins securing the shift linkage to the transmission.
- Disconnect shift cables - Loosen cable clamps and detach shift selector and speed control cables from transmission.
- Remove transmission - Support transmission and take out mounting bolts. Carefully separate from mower deck.
- Install new transmission - Position replacement transmission, aligning mount holes. Insert and hand tighten mounting bolts.
- Reattach linkages - Reconnect the shift selector and speed control cables to proper fittings on new transmission.
- Refill oil - Add new transmission oil to proper level based on dipstick or fill plug.
- Reconnect spark plug wire - Reattach spark plug wire once transmission is fully installed.
- Test operation - Start mower engine and check gear engagement and speeds to verify proper operation.
5Lawn Mower Transmission Assembly
Common Solution
Repair Instructions:
The drive belt in your lawn mower, which is connected to the engine crankshaft, is responsible for powering the transmission and turning the wheels. If you suspect a problem with the transmission, run the mower and observe the transmission. If the transmission pulley is rotating but the wheels aren't, it's a clear signal that the transmission is faulty. Bear in mind that you can't repair a malfunctioning transmission; if it's defective, the only solution is to replace it to ensure your lawn mower operates properly.
How to Replace Lawn Mower Transmission Assembly
- Disconnect spark plug wire - Locate the spark plug wire and detach it from the spark plug to prevent accidental starting.
- Drain oil - Remove the drain plug and empty old oil from the transmission case if applicable.
- Detach drive linkage - Take out clevis pins, washers and cotter pins securing the shift rods to the old transmission assembly.
- Disconnect cables - Loosen clamps and detach selector and speed control cables from the faulty transmission.
- Remove assembly - Support the transmission assembly and take out mounting bolts. Carefully detach from the mower.
- Install replacement - Align the new transmission assembly and reinstall mounting bolts. Tighten bolts to specified torque.
- Reattach linkages - Reconnect the selector and speed control cables to the proper fittings on the transmission.
- Refill oil - Add new transmission oil if required for the replacement assembly to reach full mark.
- Reconnect spark plug wire - Reattach the spark plug wire once the transmission is fully installed.
- Test operation - Start mower and check gear engagement and speeds to verify proper operation.
6Lawn Mower Traction Control Cable
Common Solution
Repair Instructions:
There could be an issue with the traction control cable in your lawn mower—it might be broken or not correctly adjusted. To diagnose this, see if the cable moves freely. If it doesn't, try applying a bit of oil to the cable end to lubricate it. However, if lubricating the cable doesn't improve its movement, it's likely you'll need to replace the traction control cable to ensure your lawn mower operates as it should.
How to Replace Lawn Mower Traction Control Cable
- Disconnect spark plug wire - Locate the spark plug wire and detach it from the spark plug to prevent accidental starting.
- Move control lever - Shift the traction control lever to release tension on the old cable.
- Loosen cable clamps - Use pliers or screwdriver to loosen any cable clamps on the old traction control cable.
- Detach old cable - Pull the cable free from the adjusters, pulleys, and lever. Note routing path.
- Thread new cable - Following same path, thread the replacement traction control cable through the pulleys and adjusters.
- Attach to lever - Insert end of new cable into the control lever and secure with retaining clip or pin.
- Tighten clamps - Position cable clamps over new cable housing and tighten to keep firmly in place.
- Adjust tension - Use adjusters to get proper tension in the new traction control cable.
- Reconnect spark plug - Reattach the spark plug wire once the new cable is installed.
- Test operation - Start mower engine to verify smooth engagement using the replaced cable.