When your zero turn stops moving, the last thing you want to do is tow it or use another piece of equipment to pull it back to the house. Doing so can damage the transmission and you can end up with a large repair bill that could have been avoidable.

A John Deere zero turn may not move or go forward when the bypass lever is not in the operating position; the v-belt is worn or has fallen off; the pulleys or idler arm spring are worn; the hydraulic fluid level is low or hot, or there is air in the hydraulic system.

Follow all safety precautions outlined in the operators manual. Take caution when working around a hot transmission.

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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.

Reasons a John Deere Mower Won’t Move or Go Forward

John Deere Manual Transmission Bypass Lever is Not in the Operating Position

A John Deere zero-turn pumps transmission fluid to the wheel motors to turn the wheels. The fluid pressure is so great that you will not be able to manually move the mower without engaging the bypass levers.

When the bypass levers are engaged to push the mower, it must be disengaged once you are finished.

If you recently transported your mower or worked on your mower where you had to engage the bypass levers, you may have forgotten to move the bypass levers to the operating position so the transmission works to move the wheels.

You will find a couple of bypass levers on a John Deere zero-turn mower, one for each transmission (left and right). When engaging and disengaging the levers, make sure the mower is parked on a level surface and the parking brake is engaged.

John Deere Drive or Pump Belt is Worn, Loose, or Broke

The hydraulic pump is powered using a v-belt off the engine. When the belt is loose or it falls off the pulley, your John Deere will fail to move.

Check your John Deere belt to make sure it is positioned correctly on the pulleys. If the belt appears worn, cracked, stretched, or broke, you must replace the belt.

Bad John Deere Tensioner Pulley

If your belt does keep falling off and it is not worn or stretched, check the tensioner pulley. The tensioner pulley is often made from hard plastic with a bearing in the center.

A pulley can break or the bearing can fail causing the belt to fall off or stop rotating around the pulley.

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

Worn or Missing John Deere 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 John Deere Mower

It’s important to keep your transmission system performing at its best by regularly checking and servicing the transmission as required. This includes changing the hydraulic fluid and filters.

Some transmission systems found in entry-level John Deere zero-turn mowers are sealed and unserviceable. This means you cannot change the hydraulic oil.

However, you must still top it off if it gets low. Refer to your operator’s manual to find out whether or not you are required to perform regular service on your transmission.

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

Keep in mind, the first hydraulic oil change is performed at a sooner interval than the others. Running your mower with old or low hydraulic oil can cause your lawn mower not to move or seem very weak while running.

When your hydraulic oil is low, add more hydro oil until the fluid level reaches the full level on the transmission overflow tanks 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 John Deere Zero Turn

When there isn’t enough hydraulic fluid or the fluid has become old or bad, it won’t efficiently lubricate the hydraulic system. This can cause friction to build causing the hydraulic fluid to overheat.

Hot hydraulic fluid can also indicate extensive damage in the transmission.

I recommend taking a John Deere mower to the dealership when you experience a mower that is running fine when it is cold but stops running when it gets hot. It’s best to have an experienced mechanic check the transmission to determine how much damage has occurred.

Air in the Hydraulic System in Your John Deere Zero Turn

After changing hydraulic fluid, you must bleed all of the air out of the system. Air in the system can make your mower move slowly or not at all.

Air can be removed from the system on most John Deere zero-turn mowers by raising the drive tires off the ground and allowing them to spin forward and backward.

Before doing this, make sure the mower is placed on a level surface. Use wheel chocks to prevent the mower from rolling forward.

Raise the rear drive tires off of the ground and allow them to spin forward and backward until you don’t hear excessive noise and the wheels move at a normal speed.

Refer to your operators manual for detailed steps to remove air from your John Deere’s hydraulic system.