January 01, 2015

Walk-behind lawn mower common questions

Walk-behind lawn mower common questions.
Walk-behind lawn mower common questions.

These common questions about walk-behind lawn mowers are the ones our experts hear the most often from our customers.

You might also find the help you need by checking the common symptoms and solutions for walk-behind mowers.

When you’re ready to make a repair, search your model number to find replacement parts. Sears PartsDirect has the part you need, no matter where you bought your walk-behind mower.

Why is my new Craftsman lawn mower engine locked up?

In the shipping carton for many models of Craftsman lawn mowers, the bottom ends of the handle extend into the mower deck. The ends of the handle block the blade and prevent the engine from rotating. 

Pull the handle up into the operating position as shown in the owner’s manual to fix this problem. The blade will then spin freely and the engine will crank properly.

Where can I find parts for my lawn mower engine?

The mower engine parts are often listed under the engine’s model number rather than the mower’s model number. To find the engine’s model number, check the engine itself or search for the mower’s model number to find its parts list, which will include the engine. When you have the model number for the engine, search for the model on Sears PartsDirect to find the individual component parts for the mower engine.

Can I use E85 (ethanol) fuel in my lawn mower?

Most lawn mower engines cannot use E85 fuel, which contains 85% ethanol and 15% gasoline. Many lawn mowers can only use unleaded gasoline with up to 10% ethyl alcohol (E10). Check your owner’s manual for fuel specifications.

Why does the engine stall just after I start my lawn mower?

If the engine stalls when you start the mower, first check the fuel level—a low fuel in the gas tank could cause the engine to die. 

A blocked vent on the gas tank cap could also cause the engine to die. Loosen the gas cap so air can flow into the tank but don’t remove the gas cap completely. Start the engine. If the engine keeps running, clean or replace the gas cap. 

A clogged carburetor could also cause the engine to die. Rebuild the carburetor if it’s gummed up.

Why does my lawn mower cut grass unevenly?

If your mower cuts the lawn unevenly, first check the settings on the adjustable wheels to make sure all the wheels are set at the same level. 

If the wheels are set properly, an engine mounting problem or a warped deck could cause an uneven cut. 

If the grass is tattered and turns brown, the blade could be damage. Replace the blade if it’s bent or damaged.

Why does my mower shake a lot? 

A loose or damaged blade could cause the mower to vibrate severely.  Check the blade and tighten it if necessary. If the blade is bent or damaged, replace it

Also make sure the engine's mounting bolts are tight.

Why won’t my lawn mower restart after I hit something?

If you hit a tree stump or rock while mowing, the flywheel key can shear off to prevent further damage. Replace the flywheel key if it’s broken or damaged. 

Hitting and object could also damage the blade. Replace the mower blade if it’s damaged. 

If the engine is locked up, the crankshaft could be bent or the mower engine could be damaged.

How do I override the operator presence control bar on my lawn mower?

The operator presence control system should not be overridden. It’s required for the safe operation of the lawn mower.

How much horsepower does my lawn mower have?

Lawn mower engine manufacturers no longer rate the engines for horsepower. They provide  engine cylinder displacement and torque ratings for comparing lawn mower engines.

How do I attach a new recoil starter assembly on my lawn mower?

The existing recoil starter assembly is usually riveted to the blower housing. To remove the existing recoil starter assembly, drill the rivets out of the blower housing. Use the appropriate size of nuts, bolts and washers to secure the new recoil starter assembly to the blower housing. Most replacement recoil starter assemblies include the proper nuts, bolts and washers to attach the new recoil starter assembly.

Symptoms for gas walk-behind mowers

Choose a symptom to see related walk-behind mower repairs.

Main causes: uneven wheel height settings, damaged wheel, dull or damaged cutting blade
Main causes: damaged cutting blade, loose cutting blade, damaged flywheel key, engine needs tune up
Main causes: engine needs tune up, dirty or clogged carburetor, damaged flywheel key
Main causes: dirty carburetor, bad spark plug, clogged air filter, engine choke problems, clogged gas cap vent
Main causes: drive control cable failure, worn or broken drive belt, bad transmission, broken drive wheel
Main causes: stale gas, engine needs tune up, bad spark plug, dead battery, bad recoil starter, faulty safety switch, bad ignition coil

Repair guides for gas walk-behind mowers

These step-by-step repair guides will help you safely fix what’s broken on your walk-behind lawn mower.

How to replace a lawn mower spark plug

Take a few minutes to replace the spark plug during your lawn mower's annual tune-up or if the spark plug is burnt or cracked.

Repair difficulty
Time required
 15 minutes or less
How to replace a lawn mower blade

Check your lawn mower blade regularly and replaced it if it's bent or damaged.

Repair difficulty
Time required
 15 minutes or less
How to replace a lawn mower flywheel key on a flathead engine

When you hit a hard object with your mower, the flywheel can shear to protect more expensive components. Learn how to replace this tiny but essential part.

Repair difficulty
Time required
 45 minutes or less

Articles and videos for gas walk-behind mowers

Use the advice and tips in these articles and videos to get the most out of your walk-behind lawn mower.

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