Common Faults of Excavator Fan Motors The following symptoms indicate potential failure of the cooling (radiator) fan motor on CAT E336, E345, E340, E349, and E352GC excavators. Early diagnosis helps prevent secondary damage to the hydraulic system. Fan low speed / engine overheat: Internal wear and high internal leakage. Contaminated hydraulic oil scratches motor components, reducing efficiency. Fan no rotation: Seized bearings or damaged internal rotor. Abnormal whining or