Hydraulic Fluid Change Question

Posted By: lancerplayer

Hydraulic Fluid Change Question - 03/24/20 01:05 AM

I have a new to me John Deere Z445 zero turn mower. I would like to do some basic maintenance on it before the mowing season. I plan to change the engine oil and filter, air filter, fuel filter, spark plugs, and transaxle hydraulic fluid.

Fluid spec: John Deere Low Viscosity HY-GARD® (J20D)

My question is: following the manufacturer's procedure, will I have to be concerned with any air getting into the hydraulic system? Will I have to purge the system?

1. Park machine safely on a level surface.

2. Raise operator’s seat, and clean area around reservoir cap. Remove cap.

3. Clean area around hydraulic oil filter.

4. Place drain pan with at least a 9.9 L (10.5 qt) capacity under hydraulic oil filter, turn filter counterclockwise to remove and allow oil to drain completely.

5. Apply a film of clean oil on gasket of new filter.

6. Install filter. Turn filter clockwise until gasket makes contact with the mounting surface. Tighten 1/2 to 3/4 turn after gasket contact.

NOTE: Reservoir capacity is approximately 8.5 L (9 qt). Total system capacity with filter is approximately 9.9 L (10.5 qt).

7. Fill oil reservoir with approximately 8.5 L (9 qt) of oil.

8. Install reservoir cap.

9. Start engine.

10. Move throttle lever to the 3/4 fast idle position.

11. Unlock park brake.

12. Run engine in full forward position for five minutes and then cycle motion control levers forward and rearward several times. Check for leaks around filter.

13. Stop the engine. Check oil level in reservoir. Add oil as necessary.
Posted By: samven

Re: Hydraulic Fluid Change Question - 03/24/20 01:52 AM

That is their purge method. The running for 5 min in forward just heats up the hydraulic fluid to normal operating temps then the cycle of forward reverse purges any air in the system. On my tractor after a fluid change I do similar. Idle system for 5 min then run tractor in forward for several min then cycle the front end loader up and down bucket in and out looking for jerky movement. Run PTO and lift and lower mid deck several times.
Posted By: JTK

Re: Hydraulic Fluid Change Question - 03/24/20 08:49 PM

Not sure what drive system this JD uses, but on most of them, after the refill, you pull the bypass lever on the drive, start the engine and cycle the controls forward-reverse a few times to purge the air out. If it's a separate hydraulic pump and motor drive, air will typically work it's way through the system.
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