Riding Lawn Mower Repair

A riding lawn mower saves time and energy — as long as it works. This Fix-It Guide on riding lawn mower repair tells how a riding lawn mower works, what often goes wrong, how to identify a riding lawn mower problem, and what parts and tools you will need to fix it. It then gives simple step-by-step instructions for how to remove a riding lawn mower deck and how to adjust a riding lawn mower drive belt. This Fix-It Guide also refers to rotary lawn mower repair, small engine repair, and switch repair for further information on fixing a riding lawn mower.

How Does a Riding Lawn Mower Work?

Riding Lawn Mower Repair

Components of a typical riding lawn mower.

A riding lawn mower is a gas-powered machine for cutting grass. The engine turns a rotating blade that cuts the top off the grass blades to a specified height. The operator sits atop the mower on a tractor-type seat with speed and height controls nearby. Riding mowers also can be used to pull small utility carts for other yard jobs. Other grass cutters include the reel lawn mower and the rotary lawn mower.

Fix-It Tip

Save yourself some time and money. Pull out the owner’s manual for your riding lawn mower and determine what regular maintenance is needed, then mark the jobs on your calendar. Taking care of your mower will pay off by ensuring a longer working life at lower costs.

What Can Go Wrong with a Riding Lawn Mower?

The mower may cut poorly or unevenly. The V-belts may slip or come off during use. The belt may squeal or wear quickly. The mower may vibrate excessively when the clutch is engaged. The mower may be hard to shift or may not move when the clutch is engaged. The engine may not start, may lose power, or may die during use.

How Can I Identify a Riding Lawn Mower Problem?

  • If grass is poorly or unevenly cut, try mowing at a slower speed and adjusting the riding lawn mower engine speed with instructions in your owner’s manual. Scrape away any dried grass and other debris caked under the mower deck. Sharpen or replace dull or bent blades (see the Rotary Lawn Mower Fix-It Guide). Check and replace a worn belt.
  • If the riding lawn mower V-belt slips or comes off during use, clear any debris in the belt area, adjust the drive-belt tension (see below), or have the belt replaced. Adjust and tighten pulley fasteners or have a service center replace worn parts.
  • If the belt squeals or wears excessively, adjust the drive-belt tension (see below) and look for obstructions around the belt. If that doesn’t work, take the mower in for professional service.
  • If a riding lawn mower vibrates excessively when the clutch is engaged, scrape away any debris accumulated under the deck. Balance the blade (see the Rotary Lawn Mower Fix-It Guide) and replace the blade if needed. If that fails, adjust drive-belt tension (see below). If you find that the drive belt, pulley, or other belt-drive part is damaged, consider having it replaced by a professional.
  • If a riding lawn mower is hard to shift or doesn’t move when the clutch is engaged, adjust the drive-belt tension (see below). Also make sure the mower is lubricated according to the owner’s manual specifications. As needed, have the mower serviced for damaged or maladjusted clutch/brake pedal linkage.
  • If a riding lawn mower engine doesn’t start, loses power, or dies during use, see the Small Engine Fix-It Guide for additional suggestions.

Fix-It Tip

Larger riding mowers typically have a safety switch that stops the engine if the driver leaves the seat with the transmission in gear or the parking brake off. If the engine won’t start, test the switch.

What Do I Need for Riding Lawn Mower Repair?

Replacement parts are available from lawn mower repair services or the manufacturer. Tools needed to fix a riding lawn mower include these:

  • Screwdrivers
  • Wrenches
  • Scrap lumber
  • Leather work gloves
  • What Are the Steps to Fixing It?
  • Remove the mower deck:


Wear leather work gloves when working around sharp edges such as the mower blade(s) and deck to prevent injury. You can take them off for the delicate work, but will be glad you have them on when you handle sharp edges. And never put your hands, or anything else, under the mower while it’s running.

What Are the Steps to Riding Lawn Mower Repair?

Remove a riding lawn mower deck:

  1. Make sure that the parking brake is locked.
  2. Place scrap lumber under the front and rear of the deck.
  3. Use the deck lever to lower the deck.
  4. Remove attachments from the deck.
  5. Remove the blade drive belt from the front pulley.
  6. Remove the front and rear deck fasteners, following instructions in your owner’s manual.
  7. Use the deck lever to raise the deck.
  8. Remove the scrap lumber.
  9. Remove the deck from under the mower.

Adjust a riding lawn mower drive belt:

  1. Remove the belt from the large idler pulley.
  2. Remove the belt from the adjustable idler pulley.
  3. Carefully remove the spring-loaded large idler pulley.
  4. Loosen the adjustable idler pulley and move it slightly toward the rear of the mower to tighten it–or move it toward the front to loosen it–and re-tighten the pulley.
  5. Replace the belt.
  6. Check belt tension and readjust as needed.