Massey Ferguson A.60.28 – Hydraulic Control Unit or Vehicle ECU: External Hydraulic Valve 6 Issue

Fault within the circuit or mechanical operation of the 6th external auxiliary hydraulic spool valve. The underlying condition is typically an electrical connection problem (such as an open circuit, short to ground, or short to power at the valve's solenoid) or a mechanical failure preventing the spool valve from operating correctly (such as a stuck spool, internal bypass, or pressure loss).

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714
• 7715
• 7716
• 7718
• 7719
• 7720
• 7722
• 7724
• 7726

1. 1

   Electrical Circuit Testing: Check the Valve 6 solenoid connector for corrosion or loose pins. Inspect the wiring harness for rub points, test the solenoid coil resistance, and verify ground integrity.

2. 2

   Spool Leakage Check (Mechanical): Position the control handle in 'Neutral'. Connect a hydraulic hand pump to the Valve 6 port and pressurize it to 2500 psi. If the port cannot hold pressure, oil is bypassing the spool, indicating a damaged spool bore, a failed centering spring, or internal contamination.

3. 3

   Filter & Fluid Inspection: Check the hydraulic/transmission oil filters. Contaminated fluid is responsible for over 80% of spool valve failures.

4. 4

   Physical Inspection: Check for external leaks around the valve stack, sluggish response, or a control lever that feels sticky or binds.

1. 1

   Relieve Pressure

   Turn off the tractor and cycle the hydraulic controls to relieve all residual pressure in the system.

2. 2

   Remove the Valve

   Disconnect the hydraulic lines and the electrical harness from External Valve 6. Unbolt the valve from the distribution stack.

3. 3

   Disassemble and Clean

   Carefully disassemble the spool valve. Clean all components thoroughly to ensure no foreign matter or contamination remains.

4. 4

   Inspect for Damage

   Inspect the precision-machined cylindrical piston (spool) and the valve body bore. If the castings are cracked, bores are deeply scored, or clearances exceed 0.001 inches, the valve cannot be rebuilt and must be replaced.

5. 5

   Rebuild

   If the metal components are intact, use a spool valve rebuild kit to replace all elastomeric seals, O-rings, and backup rings. Ensure the centering spring is intact and properly seated.

6. 6

   Reassemble and Install

   Lubricate the new seals with clean hydraulic fluid, reassemble the valve, and reinstall it onto the tractor using proper torque specifications for the hydraulic unions.

7. 7

   Clear Codes

   Reconnect the electrical harness. Access the control unit dashboard to delete the error code and unlock the valves. Test the hydraulic function.