When & Why You Should Purge Husqvarna Hydrostatic Transmission?
When the hydrostatic transmission on your Husqvarna mower is not producing consistent power, it’s time to purge it. Purging your old transmission will help you save on maintenance costs and can greatly improve the performance of your mower.
Most of the time, you might face a lack of power when climbing hills. The transmission is not delivering the power it once used to. At this point, you might be wondering if you can simply replace the drive belt. Unfortunately, chances are, there might be no improvement at all.
Why Should You Purge Husqvarna Hydrostatic Transmission?
It is common for Husqvarna riding lawnmowers to have sealed transmissions. This means that the transmission does not require maintenance. So why should you purge the transmission?
A lawnmower’s transmission mechanism can get affected when air gets stuck in its hydraulics system, leading to additional issues. When the transmission is changed, or the shipping process occurs, air can get into the transmission system.
If you have owned a Husqvarna riding lawn mower for a long time or if it has just been purchased, the transmission needs to be adjusted. The hydraulics will be protected from air damage this way.
A few things can be affected by the presence of air that replaces the oil. In this case, the oil refers to the hydraulic fluid. During use, the lawn mower’s wheels, whether going forward or reverse, can become sluggish.
The parts, such as the engine, can also lose power. Therefore, when using a new mower or after a long period of time, it’s wise to purge the transmission.
How To Purge Husqvarna Hydrostatic Transmission?
An inevitable amount of air remains in the transmission after it has been serviced or its oil has been changed. It is this air that is removed through the purging process.
Ensure that each transmission has the appropriate level of oil before starting. The owner’s manual specifies the correct level for your vehicle. If they are not, fill them up to that level. Most Husqvarna machines have oil reservoirs that are easily accessible.
- It’s necessary to hoist the drive wheels out of the ground and block the non-powered wheels to purge the system.
- Make sure the bypass valve is open on the transmission.
- Ensure that the engine is running at a normal speed by advancing the throttle.
- If the brake is activated, disengage it. Slowly reverse the direction by putting the directional control in forward neutral.
- Bypass valves do not allow the drive wheels to turn when they are open.
- The process should be repeated about a half dozen times. The next step is to turn off the engine. The engine on the machine should now be restarted after the bypass valve is closed.
- Push the throttle forward again. Close the bypass valve while rotating the directional control about half a dozen times in forward and reverse.
- Even though the wheels are turning, there is no load on them. Make sure the transaxle oil level is correct by shutting down the engine.
- If necessary, add more oil. Once the purge process is complete, always close the bypass valve.
- The transmission of your Husqvarna mower should now perform properly under normal operating conditions once you have completed the purge process.
Occasionally, the purge process may need to be repeated until all the air has been removed. When the transmission runs smoothly with normal noise levels and moves forward and reverse at normal speeds, it is considered purged. The air purging process is now complete.
Problems Associated With Hydrostatic Transmission:
There are often issues with hydrostatic transmissions. Fluid problems are most often caused by mechanical parts. It is not uncommon for even a brand-new Husqvarna lawn mower to face this problem.
A blocked filter or broken hose might cause hydrostatic transmission problems if one of these components fails mechanically. Leakage and viscosity are also concerning issues, but oil shortage is the most serious.
- The Viscosity
Temperature influences oil viscosity. Therefore, your machine will perform at its best regardless of the weather if you select the correct oil.
- The Leakage
When there is an oil leak, the internal pressure will be drastically lowered, affecting movement, shifting, etc.
When Should You Consider Purging The Transmission?
There is no need to monitor fluid levels on Husqvarna riding lawn mowers because of their sealed transmissions.
The presence of air in the system, however, can affect the forward and reverse power supplied to the lawn mower’s wheels. A hydrostatic system may display the following symptoms:
- The life cycle of components has been shortened
- Excessive oil expansion at high operating temperatures.
- After a short period of operation, there is no power or drive
- Operational noise increases a lot
What If You Are Unable To Purge?
In the event of transmission problems, purging is one of the most reliable solutions. However, in case it does not work, you can examine the hydraulic system entirely to troubleshoot the problem.
Make sure the oil level is at the required level; if it’s lower, you need to add more. It is also a good idea to check for leaks in your hoses and other components. The cooling fins of the pump should also be cleaned and examined for defects.
Alternatively, if all the above does not make a difference, the old fluid may be causing the problems. Therefore, you must replace it. Again, consult an expert if the problem cannot be resolved.
Alternative Option
Give this option a try. Put in a heavier oil – 50 weight – in place of all the transmission oil in the transaxle. Look for a drain plug on your transaxle.
The lawn tractor’s transaxle will need to be removed otherwise. Bleed the system next by following these steps:
- Lift the tractor’s rear wheel off the floor and place it on jack stands.
- Put the engine in low gear and start it.
- Alternate pressing forward and reverse while opening and closing the bypass valve.
- Increase the engine speed as soon as the wheels begin to turn.
- The transaxle should be fully responsive after several quick forwards or reverses with panic braking stops.
- Place the tractor on wheels and remove the jack stands.
- Check the oil level once more.
You can climb hills like never before with your tractor if you refill the tractor with 50 wt. oil. This will work like new or better than 30 wt. oil during the assembly process.
What Is the Right Fluid For Husqvarna Hydrostatic Transmissions?
It depends on the model of the transmission to use the appropriate transmission fluid. There are many transmission fluids, including non-synthetic engine fluid 10w-30 and non-synthetic engine fluid 10w-40.
You can use non-synthetic engine fluid in the Rider 155 and 175 transmissions. Higher-grade fluid is used in transmission systems with more power.
What Is The Recommended Interval For Changing Hydrostatic Transmission Fluid?
Your first oil change should take place within 50 hours. Afterward, you need to change it every 200 hours. It is also a good idea to change the oil filter when doing a fluid change.
The Bottom Line
When the air gets trapped in the hydraulics of a lawn mower, the transmission can suffer. As a result, it’s a good practice to purge the mower’s transmission before assembling it.
Even if you are unfamiliar with this troubleshooting procedure, transmission purging can restore proper operation to your Husqvarna lawn mower.
