How To Purge Husqvarna Hydrostatic Transmission?

How To Purge Husqvarna Hydrostatic TransmissionHusqvarna riding lawn mowers commonly come with a sealed transmission and hence, they do not need any fluid maintenance.

However, if you buy a new Husqvarna riding lawn mower or have already kept it for a long period, you need to adjust the transmission in order to eliminate the air to prevent it from affecting the hydraulics system.

When the air gets stuck in the hydraulics system of a lawnmower, the transmission mechanism gets affected which can lead to a few additional problems. The air probably enters the systems during the shipping process or when you change the transmission.

The presence of air which replaced the oil (fluid), can affect a few things such as the engine becoming sluggish and also affect the delivery of power to the lawn mower’s wheels for its movement (forward and reverse).

So, because of that reason, it’s a smart decision to purge the transmission when you are using the mower for the first time (new mower) or after a long period.

What is Purging a Transmission?

This is the process of letting out the trapped air in a transmission line. Most transmission lines have transmission fluid in them. They are designed to use the fluid to generate enough power to move the vehicle. But once air penetrates the transmission, it will no longer work normally. And in most cases, the air-filled transmission isn’t able to move the vehicle.

In some cases, it will move very slowly with more than the usual input. And that can increase the rate of wear and tear. So, you have to get the air out of your tractor’s transmission line by purging it.

What Kind of Fluid Goes into a Husqvarna Hydrostatic Transmission?

The appropriate transmission fluid depends on the model. Basically, there is a long list of transmission fluid types, and some of them are 10w-30 non-synthetic engine fluid and 10w-40 non synthetic engine fluid.

Rider 155 and Rider 175 transmission engines use the 10w-30 non-synthetic engine fluid, while the Rider 155 AWD and Rider 175 AWD use the 10w-40 non synthetic engine fluid. More powerful transmission systems use higher-grade fluid.

How To Purge Husqvarna Hydrostatic Transmission:

The condition of air replacing the oil in the hydraulic system is known as cavitation. The pump should pressurize the fluid (oil) instead of air to generate the pressure needed by the system to deliver power for the lawnmower movement. So this is why we need to get rid of the air.

Let’s see the steps on how to purge the Husqvarna hydrostatic transmission as listed below. Check it out!

  1. To begin, we need to elevate the operator seat (on the left side) to the ideal position by lifting the lift lever.
  2. Then, set the freewheel control (located at the back) outward and down by pulling it. This is to disengage the transmission.
  3. Next, find an open space around your lawn and push your Husqvarna lawn mower over there.
  4. Now, you need to sit at the operator’s seat to do the next step.
  5. Using your foot, press the brake pedal forward and hold it (you are now engaging the brake). Stay holding it until you are told to press and release it slowly on step 10, and eventually disengage it on the next step 16 as mentioned below.
  6. Press the attachment clutch to switch it on to release the cutting blades.
  7. Set the throttle control to the fast setting by pushing it upward and pull out the choke located below it to make it engaging.
  8. Plugin the ignition key and turn it to the right, then remove it as soon as the engine is running.
  9. After that, set the throttle control in a slow setting by pushing it downward. The motion control lever should be positioned on the middle (center) of the right side’s seat which is a neutral position.
  10. Slowly press and release the brake.
  11. In step number 9, the motion control lever is in a neutral position, right? Now, you need to move it upward and downward, for 5 seconds each. Upward is “Forward”, hold for 5 seconds. Then, downward (“Reverse”), hold for 5 seconds. Do it for 3 cycles repeatedly.
  12. After done 3 cycles, set back the motion control lever to the neutral position.
  13. Okay so now, when the motion control is already in a neutral position, you can plug in the ignition key back to turn the engine off.
  14. Next, you need to engage back the transmission. The step is vice versa of step number 2; Invert the freewheel control by lifting it and pushing it inward.
  15. Once again, restart the engine back. At this time, the throttle control should be set to one-half speed.
  16. Now, you can disengage the brake slowly.
  17. Next, you need to drive towards approximately 5 feet by setting the motion control lever to the “Forward” position. After that, do the versa; in the “Reverse” position of the motion control lever, drive backwards around 5 feet away. And, set it to a neutral position once done.
  18. Do the forward-reverse-neutral process in 3 cycles repeatedly.
  19. You are done!

If Purging Does Not Work…

Purging is one of the reliable solutions for transmission problems but if it does not work out, you can try to troubleshoot the problems by examining your hydraulic system entirely.

Check the oil level and if it is lower than the required level you need to add it. You may check for leaks in your hoses and other components as well. You also should clean up the pump cooling fins and examine if there is any sign of defects there.

Or, if all above does not make any changes, the problems may be caused by the old fluid. So you need to replace it with the new one. However, if the problem is not solved, seek an expert for advice.

The Hydrostatic Transmission Potential Problems:

Hydrostatic transmission issues are common. A brand-new Husqvarna lawn mower and any other brand may appear to be in perfect condition but still will face this typical occurrence.

The mechanical parts which the fluid flows through are commonly the sources of problems. If any mechanical failure in these components, such as a blocked filter, or even a broken hose, it might create hydrostatic transmission problems.

On the other hand, oil shortage is the most concerning issue; leakage and viscosity.

  • Leakage: Any oil leak will drastically decrease internal pressure which will cause movement difficulties; affect the shifting process etc.
  • Viscosity: The viscosity of an oil is affected by the surrounding temperature. As a result, selecting the suitable oil will enable your machine to work at its optimum in any reasonable weather.

When the control arm is out of alignment, shifting issues will arise. When the lawn tractor begins to move on its own, you should check for oil leaks first. If it cannot get fit, it is time to retrieve and repair your adjustment bolt.

Why Doesn’t My Hydrostatic Transmission Move?

Once the hydrostatic transmission system fails, the vehicle won’t move. And there are three major causes of failure in hydrostatic systems. First of all, when the hydraulic fluid becomes too old, it will lose its viscosity and lead to the failure of the transmission system. This is why it’s important to follow the oil change and maintenance instructions of the manufacturer.

You must first drain the system of the oil completely before replacing it with fresh oil. Also, if you don’t use the recommended oil, it’s possible for the hydrostatic transmission to fail. That means you must use the recommended fluid for your engine.

The second reason why your hydrostatic transmission may not move is when air is in the system. It will prevent the hydraulic fluid from working with the system properly. In that situation, you need to get rid of the air as quickly as possible. The process of expelling air from your transmission system is known as purging.

The third reason why your hydrostatic transmission fluid won’t move is when there are leaks in any of the transmission hoses. Fluid will leak out through the point of leakage, and the remaining fluid will not be enough to get the job done.

Whatever the problem is, it’s always a smart idea to consult a specialist to fix your tractor. It is not advisable to try to fix the problem yourself if you are not a professional. You could make things worse.

Final Words

Finally, we come to the end. Solving hydrostatic transmission could be tricky if you do not know how to do it. This article would be a lifesaver for you as it provides simplified steps to be followed. Perhaps it would be very useful for you. Happy trying!