Skip to Content

Your Simplicity Zero Turn Won’t Move Forward or Reverse

You have a zero-turn mower that is moving slowly or just stopped moving. It could be something as simple as a worn part or as serious as a damaged transmission.

A Simplicity zero-turn mower won’t move or go forward due to engaged transmission bypass levers, worn or broken tensioner, worn tensioner pulley, stretched or missing tensioner spring, old or hot hydraulic oil, insufficient oil level, or air in the hydraulic system.

Before performing any work on your Simplicity, follow the safety instructions provided in your operator’s manual to prevent injury. This includes removing the spark plug boot(s) and the ignition key.

Simplicity zero turn won't move forward or revers

This post may include affiliate links. Purchases made through these links may provide a commission for us, at no extra cost to you. As an Amazon Associate, we earn from qualifying purchases.

Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

7 Reasons a Simplicity Mower Won’t Move or Go Forward

Simplicity Manual Transmission Bypass Lever is Not in the Operating Position

Fluid in the transmissions is used to pump fluid to turn the wheels on a Simplicity zero-turn. The pressure is so great that the operator won’t be able to manually push the mower without bypassing the transmissions.

You may have left the bypass levers engaged and forgot to place the transmission bypass levers in the DRIVE/CLOSED position. This will prevent your mower from turning the wheels while moving using the speed levers.

You will find two bypass levers on a Simplicity, one for the left transmission and one for the right transmission. You will find these near each drive wheel. Make sure they are in the DRIVE/CLOSED position.

Simplicity Drive or Pump Belt is Worn, Loose, or Broken

Check your Simplicity drive belt to make sure it hasn’t fallen off and is positioned correctly on the pulleys. If the belt appears worn, cracked, or broken, you must replace the belt.

Bad Simplicity Tensioner Pulley

Tensioner Pulleys are often made from hard plastic with a bearing in the center. The pulley can break or the bearing can fail on a Simplicity lawn mower.

If you find a bad pulley, replace it with a new one. Keep the tensioner arm greased so it does not seize and is allowed to have some movement.

Worn or Missing Simplicity Idler Arm Spring

The purpose of the idler spring is to place tension on the drive belt. Replace the spring if it is broken, missing, or stretched.

Low Hydraulic Fluid Level or Old Hydraulic Oil in Your Simplicity Mower

Running your mower with old or low hydraulic oil can cause your lawn mower not to move or seem very weak while running.

It’s important to keep your transmission system performing at its best by regularly checking and servicing the transmission as required. Some transmission systems found ON Simplicity zero-turn mowers are sealed and unserviceable.

This means you cannot change the hydraulic oil and filter. Refer to your operator’s manual to find out whether or not you are required to perform regular service on your transmission.

If your model is non-serviceable, but allows you to add hydraulic oil into the transmission oil tanks, add oil to each tank (left and right side) until it reaches the FULL COLD level.

If your Simplicity mower has a serviceable transmission, consistent hydraulic oil changes at intervals recommended by Simplicity must be completed.

Keep in mind, the first hydraulic oil change is performed at a sooner interval than the others. Simplicity recommends using 20W-50 oil in the transmissions.

The hydraulic oil and filter must be changed after the first 100 hours and then every 400 hours after.

When your hydraulic oil is low, add more hydro oil until the fluid level reaches the FULL COLD level when your hydraulic oil is cool. It’s also a good idea to check for hydraulic fluid leaks to make sure your fluid level isn’t low due to a leak.

Hot Hydraulic Fluid in Your Simplicity Mower

When you operate your Simplicity lawn mower with bad hydraulic fluid or low fluid, the oil is not able to efficiently lubricate the hydraulic system causing increased friction and overheating of the hydraulic fluid.

Hot hydraulic fluid can also result in more extensive damage.

I highly recommend taking the lawn mower to your local Simplicity dealership if you experience leaking from your hydraulic pump.

If your mower runs fine when it is cold, but stops running when it gets hot, you should have an experienced mechanic check your transmission.

Air in the Hydraulic System in Your Simplicity Mower

After changing or adding hydraulic fluid, you must bleed all of the air out of the system. Air in the system can prevent your mower from moving.

Remove air from a Simplicity hydraulic system:

Air can be removed from the system on most Simplicity zero-turn mowers by placing the mower on a flat surface.

  • Secure the front wheels using wheel chocks to prevent the mower from rolling forward.
  • Raise the rear drive tires off of the ground using jack stands.
  • Release the bypass levers so they are in the PUSH/OPEN position.
  • Start the engine and remove the parking brake.
  • Using the speed levers, move the levers forward and backward about 6 times.
  • Stop the engine and engage the parking brake.
  • Close the bypass levers so they are in the DRIVE/CLOSED position.
  • Using the speed levers, move the levers forward and backward about 6 times.

Repeat these steps as necessary until you don’t hear excessive noise and the wheels move at normal speeds. When air is removed from the system, the oil level goes down. Check the hydraulic oil level and add more oil as needed.

Refer to your operator’s manual for detailed steps to remove air from your model’s hydraulic system.