Page 180 - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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164 Automobile mechanical and electrical systems

Figure 2.166 Water pump impeller

Figure 2.167 ‘V’ belt and pulley

Figure 2.168 Multi-V belt and pulley
The drive components for the water pump on earlier cars consisted of a ‘V’ belt
that also drove the alternator ( Fig. 2.167 ). On many other vehicles multi-V belts
are also in common use ( Fig. 2.168 ). An adjuster for the belt is provided on the
alternator mounting, or as a separate tensioner. The toothed camshaft drive belt
is used to drive the pump on some vehicles ( Fig. 2.165 ).
A fan is used to ensure an adequate air fl ow through the radiator when this is not
provided by the forward speed of the vehicle. The fan was traditionally fi tted to
the front of the water pump and attached with the same bolts as the drivebelt
pulley. Some longitudinal engines still use this system, but the fan, formerly a
pressed-steel component, now incorporates a thermostatic viscous hub and
nylon fan blades ( Figs 2.169 and 2.170 ). The viscous hub is a fl uid clutch using
silicon oil. The operation of the clutch is temperature controlled with a bimetallic
valve. When the air fl ow temperature over the viscous hub is cool, the valve