Viscous fan coupling: replacement and selection

When and why it is necessary to replace viscous fan coupling

Manufacturers do not specify the intervals of the viscous fan coupling replacement. Part replacement is performed at its jamming, cracking or deformation of the heated plate or casing, in case of free play or mechanical damage of the bearing, working liquid leakage, and loss of ability of liquid to transmit rotational torque.

As a rule, the cause of working liquid leakage lies in seal elements elasticity loss. Changing of liquid operational characteristics occurs in course of time due to contamination by wear debris and oxidation products. Breakages of the bearing usually occur as a result of impacts, metal fatigue wear and abrasive wear appearing due to grease contamination. Damaging of the heated plate can happen as a result of impact, for instance in a road accident, and due to specifics of its operation (frequent bending and unbending).

Defectiveness of the viscous coupling is indicated by increasing of engine temperature at idling or low rpm (for example, in a traffic jam).