The 7 Most Common Mechanical Problems For Riding Lawn Mowers

Maintaining a big lawn is a big job, and specialized tools are required to do the necessary work efficiently. The riding lawn mower is one of the most important pieces of equipment used for this task. Like any piece of machinery, a riding mower is not invulnerable and you can expect to face breakdowns or maintenance issues from time to time.

This article will familiarize you with seven of the most common mechanical issues that riding mower owners have to deal with. You can use what you learn here as guidance in your own repair work, but bear in mind that not all problems can be solved by untrained hands. Always consult with a licensed professional technician when your riding lawn mower needs extensive repairs.

1) The Engine Won’t Turn Over

This is an extremely common issue to run into, especially if your mower has been left idle for an extended period of time.

Start by checking all of the safety features of the mower for proper operation. Sit on the mower and confirm that the parking brake is on and the mowing deck isn’t engaged. Make sure you’re toggling all of the safety switches as directed by your operator’s manual.

If you don’t have an issue with the safety features, you next likely culprit is the battery. Battery cables can occasionally pop off the battery’s terminals. If you find this is the case, reconnect them securely before trying to start the mower again. Remember that the black negative cable must be attached to the battery’s negative terminal, which should be marked with “NEG”, “-“, or “N”. The red positive cable needs to be attached to the battery’s positive terminal, which will be marked “POS”, “+”, or “P”.

SAFETY WARNING: Riding mowers operate using batteries which contain sulfuric acid, a hazardous material. Do not puncture the battery or spill its contents under any circumstances. You can test your battery’s charge by using a hydrometer to check the specific gravity of each of the cells in the battery. Charged cells will have a specific gravity of 1.250. If you determine that your battery’s fluid levels are low, add distilled water until the fluid level rests just underneath the split rings. Recharge the battery using no more than 5 amps of current. Charge until you confirm that each cell’s specific gravity is at 1.250. If you cannot bring the battery up to this point, it needs to be replaced.

After you’ve checked the battery, look at the fuses next. Check your operator’s manual to make sure you inspect all of the mower’s fuses; they may be located in different areas. Replace any blown fuses with new automotive fuses that match their amperage.

Finally, locate the engine’s ground wire and confirm that it’s in proper working order. The ground wire should lead from the engine to either an unpainted patch of the mower’s frame or a mounting bolt.

2) The Engine Turns Over But Will Not Catch

If you can bring your riding mower close to life but not actually engage the engine, a lack of fuel is likely the problem. You need to have a full fuel tank, a fueled carburetor, and a clear fuel line. If you determine that you have a clogged line, clean it out and install a new fuel filter.

The engine will not start unless the mower’s throttle and / or choke are set correctly. Double-check the appropriate settings in your owner’s manual; the right settings vary from model to model.

If the controls are set correctly and you have fuel, your problem may be a faulty spark plug. You can check this using a spark plug tester. Check each plug’s seating and clean its cap. Any spark plugs which still will not work should be replaced.

3) The Mower Smokes When The Engine Is Running

This alarming-looking problem is typically caused by having excess engine oil in the system. It should resolve itself once the excess is burned off; you can hurry this process along by checking your mower’s oil level and draining off oil.

f your mower’s oil level is within the proper marks and the engine is still smoking, you might have a crack or break somewhere in the system which is making it impossible to fully seal the crankcase. This can happen if you have a breakage or defect in a valve cover, dipstick tube, dipstick, engine breather assembly, or other vital parts. Assess the condition of the parts carefully and replace broken ones; this should restore the crankcase to full working order.

4) Constant / Excessive Vibration

Violent vibrations are typically caused by damage to a mower’s spindles, pulleys, or blades. These issues are typically caused by running them over a solid object, damaging them and spoiling their alignment. Mowing over rocks, roots, and sewer outlets can all cause this type of damage. Any parts showing evidence of this type of damage need to be replaced.

Excessive vibrations might also be caused by loosened or absent mounting bolts, a cutting deck which is set at the wrong height, or idling the engine at low RPMs. You should also check the machine for damaged or twisted belts. Check the seating of all belts and replace any that show evidence of wear and tear.

5) Poor Performance With Discharging, Bagging, or Mulching

If your mower isn’t getting rid of cut grass the way it’s supposed to, there are several potential problems to check for. First, verify that you’re running the engine at full throttle; the discharging, bagging, or mulching functions will not work at full efficiency at low RPMs.

Take a close look at the set of the mowing deck. It should be level all the way across the width of the mower, while the front end of the deck should be slightly lower (3/8″) than the rear.

Finally, you should take a look at the condition of your mower blades. If they are dull they could be delivering unsatisfactory results. Sharpen or replace them as necessary.

Be aware that adverse conditions may impede your mower’s functions. Running it over grass that’s wet or too tall will reduce its effectiveness.

6) The Mower’s Blades Don’t Engage In Reverse

This may not be a technical problem at all. Prior to 2005, mowing in reverse was made impossible as a safety feature. Newer mowers may have this capability, though. Check your owner’s manual for reverse mowing information and instructions.

7) The Tractor Is Still In Gear In Neutral

If your mower refuses to move while you have it in neutral, the transmission relief valve is probably not set correctly. The mower’s brake may also be sticking. Check the owner’s manual to confirm that you have the relief valve set in the right position.