John Deere 544P High Coolant Temperature, Fan Operating
Fault Codes & Symptoms
High Coolant Temperature Related symptoms: - Slightly reduced hydraulic system performance in other circuits. - A whining noise from the fan drive system that changes with engine RPM. The engine overheats, especially when working the machine hard. The temperature gauge goes into the red.
Confirmed cause: Defective hydraulic fan motor with excessive internal leakage. Repair performed: Replaced the hydraulic fan motor. Drained and replaced the hydraulic fluid and filter for that circuit to remove any potential contamination from the failed motor. Verification: After repair, fan speed was measured with a photo-tachometer and confirmed to be within the manufacturer's specification at high idle. The machine was operated under a heavy load for 1 hour, and the coolant temperature remained in the normal operating range. Technician notes: - A spinning fan does not guarantee correct CFM. Always measure fan speed if overheating is a symptom. - The leak at the case drain line was the key indicator. This showed that fluid was bypassing internally instead of turning the motor. - Always change hydraulic fluid and filters after a major component failure like a motor to prevent repeat failures.