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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). Also specific sound can be heard (humming, screeching). Another sign of viscous coupling defect – lowering of fan rotation speed at high engine rpm.

It is recommended to perform replacement of the viscous fan coupling at a service station, as access to this component is complicated. Also, during the procedure, special equipment can be necessary.

How to select viscous fan coupling

The viscous fan couplings for various cars are presented in the assortment of such brands as Swag, Thermotec, Van Wezel, Dasis. The components of these brands are notable for durability and high quality.

In order to select the part properly, you need to take into account the car model, production year and the engine type. Particularly, compatibility of the part by outer diameter, mounting seat diameter, and quantity of mounting holes depends on this.