How to Replace Kubota Hydraulic Cylinder Seals

Replacing the hydraulic cylinder seals on your Kubota machinery is a critical maintenance task that ensures the longevity and efficiency of your equipment. This step-by-step guide will walk you through the process, from preparation to testing, ensuring you can precisely address this task.

Cylinder Removal

  1. Safety and Preparation: Before commencing any work, ensure the machinery is on stable ground and the engine is turned off. Engage any safety locks or supports on the machinery to prevent accidental movement.
  2. Lower Attachments: Carefully lower any hydraulic attachments to the ground. This step reduces tension in the hydraulic system, making it safer to disconnect the cylinder.
  3. Release Hydraulic Pressure: Find the pressure release valve on your Kubota’s hydraulic system and carefully release any built-up pressure. This step is crucial to prevent accidental discharge of hydraulic fluid when disconnecting the cylinder.
  4. Disconnect Hydraulic Lines: Gently disconnect the hydraulic lines connected to the cylinder using the appropriate wrenches. Expect some fluid to leak out, so have rags or containers ready to catch the spillage. Cap the lines and the cylinder ports to prevent contamination.
  5. Remove Cylinder: Remove the pins or bolts that secure the cylinder to the machinery. Note the orientation and placement of any washers or spacers for correct reassembly. Carefully remove the cylinder, not damaging the rod or any surrounding components.


  • Secure the Cylinder: Place the cylinder on a clean, flat work surface. If possible, secure it in a vise with protective jaws to prevent damage to the cylinder.
  • Remove End Cap: The end cap or gland nut may be secured with bolts, a snap ring, or another locking mechanism. Remove these components carefully. Employ snap ring pliers to ease the removal process if a snap ring is used.
  • Extract Piston Rod: Gently slide the piston rod and assembly out of the cylinder barrel. Keep all parts organized and note their orientation for reassembly.

Seal Removal and Inspection

Old Seal Removal: Using a small flathead screwdriver or seal removal tool, carefully pry out the old seals from the piston and rod. Be mindful not to scratch or damage the metal surfaces.

Clean and Inspect: Thoroughly clean all parts with a suitable cleaner and inspect for wear, scratches, or damage. Pay close attention to the surfaces of the piston rod and inside the cylinder barrel, as scratches can lead to future leaks or seal damage.

Installing New Seals

  1. Seal Orientation: Refer to the Kubota seal kit instructions for detailed seal orientation and placement diagrams. Incorrect installation can lead to leaks or damage upon reassembly.
  2. Installation: Gently install the new seals using a seal installation tool or a socket with a slightly smaller diameter than the seal to press it into place. Ensure the seals are evenly seated without twists or kinks.
  3. Lubrication: Before reassembling, lightly lubricate the new seals with clean hydraulic fluid. This lubrication aids in the reassembly process and helps protect the seals during the initial operation.

Reassembly and Installation

Reassemble Cylinder: Carefully slide the piston rod back into the cylinder barrel, ensuring it does not damage the new seals. Reattach the end cap or gland nut, securing it per the original configuration.

Reinstall Cylinder: Position the cylinder back onto the machinery, replacing any washers or spacers in their original locations. Reconnect the hydraulic lines, ensuring a tight, clean fit to prevent leaks.


System Testing

  • Refill Hydraulic Fluid: Check the hydraulic fluid level and refill if necessary, using the type specified by Kubota for your machinery.
  • Bleed the System: Operate the hydraulic controls to move the cylinder through its full range of motion, bleeding any air from the system. This process may need to be repeated to ensure smooth operation.
  • Leak Testing: After the cylinder is operational, inspect all connections and the cylinder itself for leaks. Pay close attention during the first few hours of operation and address any leaks immediately.

Replacing the hydraulic cylinder seals on your Kubota equipment is a vital maintenance task that can prevent costly repairs and downtime. By following this detailed step-by-step guide, you can ensure your machinery continues to operate efficiently and reliably. Remember to always prioritize safety and consult your Kubota’s manual for any model-specific instructions or specifications.