Return to Master Table of Contents Page 28 Hydraulic System Troubleshooting, Testing and Adjustment Problem Possible Causes Remedies Swing priority not operating correctly Sticking spool. Clean/replace Solenoid valve faulty. Replace Boom and arm cylinders do not perform normally in combined operation Priority valve faulty or spool sticking. Check pilot pressure. Broken or deformed spring. Replace Excess clearance between right and left casing and valve spool. Clean/replace Clogged spool passage. Clean/replace, replace filter. Relief valve malfunctions: Pressure does not increase at all. Main poppet or pilot poppet stuck open. Clean/replace Irregular or uneven pressure.
Poppet seat damaged or pilot piston sticking to main poppet. Clean/replace Loose lock nut and adjusting screw. Readjust Components worn out, past wear limits. Replace TROUBLESHOOTING - TRAVEL CONTROL VALVE Problem Possible Causes Remedies Secondary pressure does not increase. Low primary pressure. Check primary pressure. Broken spring. Replace spring. Spool sticking. Clean, repair or replace. Excess spool to casing clearance. Replace spool casing. Worn or loose universal joint (handle) subassembly. Repair or replace U-joint subassembly. Secondary pressure too high. Dirt, other interference between valve parts. Clean, repair or replace. Return line pressure too high. Redirect return line.
Secondary pressure does not hold steady. Dirt, other interference between valve parts, or worn spool sticking intermittently. Clean, repair or replace. Interference or binding on spool return spring. Clean, repair or replace. Interference, restriction or unsteady pressure in tank return line. Repair or re-route tank return line. Air bubbles in piping (temporary) or air leak. Vent air, or repair leak. NOTE: Look for evidence of leaking oil.