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How to Solve the John Deere Hydrostatic Transmission Problems

Finding the solution to John Deere hydrostatic transmission problems can be a huge challenge. But before you try, find out whether the issue is major or minor. It is important to fix the problem at its root rather than spending a lot of money on repairs without even successful execution of the same.

If you are facing transmission problems, read on to find all the answers to your questions.

Hydrostatic Transmission of a lawn mower
Hydrostatic Transmission of a lawn mower

The John Deere Hydrostatic Transmission Problems

Troubleshooting your hydrostatic transmission begins with understanding how it works. Hydrostatic transmissions operation: it transfers power from the engine to the hydraulic pumps. It uses liquid pressure to move the wheels. 

There is no need for gears, and changing speed is smooth and efficient. Tractors with hydrostatic transmission also have variable speed settings that are controlled by levers on the console of the tractor. 

These levers determine how much fluid is sent to each wheel and whether they spin clockwise or counterclockwise. With tractors, you can adjust the speed of each wheel separately so that only one wheel spins, which can be helpful when using implements like plows or blades. 

To change speeds on a tractor with hydrostatic transmission, simply use the levers located on the console. Speed changes are smooth in tractors with hydrostatic transmission because there are no gears to shift.

If your tractor has a problem with hydrostatic transmission, it could affect all four wheels. Of course, before you begin any repairs, you’ll need to have a repair manual for your John Deere equipment. 

Hydrostatic Transmission of a lawn mower
Hydrostatic Transmission of a lawn mower

You can purchase the manuals for your tractor or zero-turn mower from our John Deere dealer locator. The correct operator manual will provide detailed information about the specific equipment that you own.

Purge Your Hydraulic Drive System

Hydrostatic transmission problems may start with air or air bubbles in the system. This situation is known as cavitation. When the pump is full of air instead of oil. The small amount of oil that is left in the pump cannot generate the pressure needed to provide power to the output shaft. 

This can happen if your mower or tractor has been stored for the winter with fuel in the tank. About all you can do to correct a problem like this is change out parts until it stops. 

If you are going to store your equipment for an extended period, it is a good idea to purge all fuel and run the engine so that all of the fuel will be burned up. 

Hydrostatic transmission problems are common in zero-turn mowers when they are stored for long periods of time without being run and purged of gasoline. It is best to follow the recommendations of the manufacturer, but the below steps will get you started.

  1. Park the mower on level ground, set the parking brake, and put the rear wheels on jack stands.
  2. Make sure the oil reservoir is filled properly according to specs.
  3. Disconnect transmission (check your operators manual to see how this is done).
  4. Sit on the mower’s seat and start the engine.
  5. With the engine running, move the throttle control to a slow position. Position the motion control levers in the neutral (N) and disengage clutch/brake pedal.
  6. Push the motion control levers forward and hold them there for a moment. This will purge any air from the forward motion system.
  7. Again, pull the motion control levers to reverse and hold them for the same time. This will purge any air from the reverse motion system.
  8. Repeat the previous 2 steps thrice to purge excessive amounts of air from the system.
  9. Set the motion control levers in the Neutral position. Turn off the engine and set the parking brake.
  10. Check the oil reservoir. Fill it up if necessary.
  11. Engage the transmission.
  12. Remove from the jack stands, then turn on engine, and disengage the brake.
  13. Move the motion control levers to the forward and roll for about 5 feet. Then slowly reverse for the same distance as before. Return the motion control levers to neutral position and repeat the steps for about 3 times.

Check The System

After you have completely eliminated the possibility that the problem is with the engine, you need to look into the entire system. The first thing to do is to check all the internal parts for any damage. 

If there are any damaged parts, replace them as soon as possible.

  1. Check if all the settings are in the right place. If not, make adjustments.
  2. Check engine oil viscosity. Make sure it is suitable for the temperature.
  3. Check the oil reservoir. Fill it up if it’s empty. Change the oil if it is too dirty.
  4. Proceed to check all your wires, clamps and hoses for any damage or sign of leaks.

Change the Hydraulic and Steering Fluids

You may be unaware that there are multiple fluids in your tractors. One such fluid is hydraulic oil. This oil is responsible for all the functions of the front axle, steering and hydraulics. 

If this oil is old or contaminated, it can cause your tractor to become sluggish and unresponsive. You need to keep a check on this fluid. If you notice your tractor becoming sluggish, it could be a sign that the fluid needs to be changed.

You should also check your steering fluid if you have steering problems. If you have no steering issues but want to ensure that your fluid has not gone bad, go ahead and drain it from the radiator into a container that is safe for disposal later on.

Engine Problem

Your John Deere lawn mower should be given regular maintenance to ensure it will be working at optimum performance. The following are some of the common problems you can encounter and how to fix them.

  1. Check first if the brake pedal is working properly. If it does not work properly, then there could be a problem with the foot pedal or linkage. The best solution to this problem is to replace the broken part.
  2. Make sure that you have disengaged the machine before trying to check if the spark plug wire is working properly or not. If you find that the wire is broken, then you have to replace it right away.
  3. Check if the safety switch is working properly. If it does not work as expected, then you have to replace it with a new one in order for your engine to run smoothly again.
  4. Make sure that the engine oil viscosity is optimum and match with what has been specified by the manufacturer of your John Deere engine.
  5. If you have tried all of these things and your John Deere mower still overheats, you may need to replace the thermostat. It can cause your mower not to move forward or reverse.
Lawn mower engine
Lawn mower engine

Electrical Problems

Electrical problems in your John Deere Mowers can be solved by you. You just need to know the right procedure to follow.

The first step is to check the battery terminals carefully. If corroded, take it to experts. Most of the time the terminals are corroded due to lack of maintenance. Make sure you always charge the batteries properly. 

Older batteries tend to lose their charge much faster than newer ones. Always have your batteries tested and replaced if found faulty. If there is any problem with its charging, get it checked at a local repair shop.

Check for fused circuits, if any, bring them to experts. It’s better if you don’t try to fix it by yourself as it can lead to serious problems like electrical fire and burning of your mower.


In conclusion, if you have had these John Deere hydrostatic transmission problems with your machines, do everything you can to rectify them. These are some simple but effective John Deere hydrostatic transmission problems. 

They are easy to solve if you have the right idea and implement the fixes in time. As long as you adhere to the suggestions we have provided in this article, your mowers should run just fine. 

Has your John Deere hydrostatic transmission stopped working? If you have and you can’t solve it by yourself, then it is time to call in a professional farm repairman.

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