While an Ariens mower that will not move can be a costly problem, there are several less expensive items that can wear or break causing a zero turn not to move.
An Ariens zero turn mower won’t move forward or reverse when the manual transmission bypass is engaged; the pump drive belt is worn; the tensioner pulley is bad; the idler arm spring is loose or missing; the hydraulic oil is low, old, or hot, or there is air in the hydraulic system.
Take caution when working with a hydrostatic transmission. Follow the safety instructions in your Ariens operator’s manual. This includes turning the engine off; removing the key, and waiting for all parts to stop moving and cool down.
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Follow all safety instructions provided in your equipment operator’s manual before 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 an Ariens Mower Won’t Move Forward or Reverse
Manual Transmission Bypass in the Wrong Position
You will find two pumps and wheel motors on the left and right-hand side of an Ariens zero-turn mower. The transmission is designed to pump transmission fluid to the wheel motors to turn the wheels.
The fluid is under so much pressure that you will not be able to move it manually without engaging the bypass lever.
The transmission bypass levers are pulled out in the bypass position when the mower needs to be “free-rolled”. These valves are often used when the mower has mechanical problems where the engine no longer runs.
If you have recently bypassed the transmission to manually move the mower, make sure you pushed the bypass transmission levers back into place so the Ariens transmission system will power the wheels.
The transmission bypass levers are located near each wheel. The lever must be pulled out to bypass the transmission and pushed in to engage the transmission.
When using the bypass levers, make sure the mower is parked on a level surface and the parking brake is engaged. Placing a transmission in bypass mode while the mower is on a hill can cause it to roll downhill.
Pump Drive Belt is Worn, Loose, or Broken
The hydraulic pump is powered using a v-belt off the engine. When the belt is loose or it falls off the pulley, an Ariens zero turn will fail to move.
Ensure the belt is securely positioned correctly on the pulleys. If the belt appears to be worn, stretched, or broken, it must be replaced. If the belt has fallen off, check the tensioner pulley or idler arm spring.
Bad Tensioner Pulley
After you have checked the pump belt’s condition and have found it is not worn, check the tensioner pulley.
This pulley is often made from hard plastic with a bearing in the center. The pulley can break or the bearing can fail. This can cause the belt to stop rotating around the pulley or the belt may fall off.
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 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
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 Ariens zero-turn mowers are sealed and unserviceable. This means you cannot change the hydraulic oil.
Consult your operator’s manual or contact an Ariens dealership for help if you are unsure if the transmission is serviceable on your model.
Running a mower with low or old hydraulic oil can cause the mower’s movement to seem weak. It may begin to run slowly or not move at all.
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.
Keep in mind, the hydraulic oil and filters must be changed after the initial 75-hour break-in period and then every 400 hours after.
Hot Hydraulic Fluid
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 your zero turn 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 and if it’s repairable or needs replacement.
Air in the Hydraulic System
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 Ariens zero-turs 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 operator’s manual for detailed steps to remove air from the hydraulic system.