Mini Excavator Hydraulic Functions Slow When Hot

Confirmed cause: The port relief valve for the dozer blade lift function was stuck partially open and adjusted well below the manufacturer's specification. Repair performed: The dozer blade lift port relief valve was removed, disassembled, cleaned, and inspected for wear. It was reinstalled and adjusted according to the manufacturer's service information. Verification: The machine was operated for several hours under similar load conditions. Hydraulic oil temperature stabilized in the normal operating range, and hydraulic function speed remained consistent. Technician notes: - The low port relief setting was likely allowing oil to bypass constantly, even when the blade was not being used. - This issue might not be obvious if the blade function seems to work acceptably; the primary symptom is the secondary effect of system-wide overheating. - Always check port relief pressures on circuits that are not actively used during the primary work cycle (like a dozer blade during trenching) when diagnosing mysterious overheating issues.