Summer is here. Grass in the yard grows fast. You pull the lawn mower to start it. But the starter motor fails. It just hums. The machine won’t start. Or it doesn’t make any noise at all.

Don’t worry. Starter motors aren’t that delicate. You don’t need to replace the whole part most of the time. You can fix it yourself easily. Today, I’ll share a simple guide to test and repair it. Even beginners can follow along.

First, get ready. Safety is always the top priority. First step: disconnect the lawn mower’s spark plug wire.Avoid accidental starts and injuries during repairs.You probably have them all at home. Find a clean spot to place the mower. This avoids losing small parts.

Next, do two basic tests on the starter motor: no-load test and load test.

The no-load test is very simple. First, remove the starter motor from the engine and disconnect the gears connected to the engine. Then connect the battery of the lawn mower, paying attention not to reverse the positive and negative poles, and observe the operation of the motor after connection. If the motor speed is uniform and there is no abnormal noise, it indicates that there is no problem with the motor itself, and the fault is likely to be caused by external circuits or gear jamming; If the motor does not rotate or rotates intermittently with loud noise, then it is necessary to disassemble the motor and inspect the internal components.

Then, do the load test. Reinstall the motor onto the engine. Restore all connections. Try to start the mower. If the motor can easily turn the engine over, it’s in good condition. If the motor hums but can’t turn the engine, or stops soon after starting, the carbon brushes are probably worn out. Or the engine might be stuck. You need to troubleshoot further.

Once you confirm the motor has issues, start repairing it. There are only a few common problems. Fix them accordingly.

First common problem: worn carbon brushes. Carbon brushes transfer electricity inside the motor. They wear down over time. This causes poor contact. Open the motor’s back cover. You’ll see the carbon brushes. If they’re less than half their original length, or have uneven wear, replace them with new ones. It only costs a few dollars.

Second problem: commutator carbon buildup. The commutator inside the motor can get covered in dust and carbon powder. This affects electricity flow. It makes the motor run poorly. Use sandpaper to gently polish the commutator surface. Clean off the carbon buildup with a brush. Don’t press too hard. Avoid scratching the commutator.

Third problem: loose or faulty wiring. Check the wires connecting the motor and battery. If the terminals are rusty or oxidized, sand them until they shine. Tighten the screws again. If the wires are damaged, wrap them with electrical tape. This prevents short circuits.

Another issue: stuck motor gear. Take apart the area where the motor connects to the engine. Check if the gear is bent or rusted. Apply lubricant to the gear. Clean out any grass and dirt inside. Make sure the gear can spin freely.

After repairs, repeat the no-load test and load test. Confirm the motor runs normally.

Finally, here are some maintenance tips. Clean dust and grass off the motor after each use. Check the wiring and carbon brushes regularly. Fix problems early. If you don’t use the mower for a long time, remove the battery and store it properly. This prevents battery drain.

Repairing a lawn mower starter motor isn’t complicated. Try these methods first. You might fix it in minutes.