26
COOLING SYSTEM
Viscous Fan Operation
A = Cold
B = Hot
1.
2.
3.
4.
5.
6.
Drive plate
Fan body
Clearance
Valve plate
Valve
7. Fluid seals
8. Ball race
9. Fluid chamber
10. Reservoir
11. Return port
Bi-metallic coil
When the engine is off and the fan is not rotating, the silicone fluid stabilises within the fluid chamber and the
reservoir. The fluid levels equalise due to the return port in the valve plate being open between the fluid chamber
and the reservoir. In this condition, when the engine is started, silicone fluid is present in the fluid chamber and
causes drag to occur between the drive plate and the body. This causes the fan to operate initially when the
engine is started.
As the fan speed increases, centrifugal force and a scoop formed on the fluid chamber side of the valve plate,
pushes the silicone fluid through the return port in the valve plate into the reservoir. As the fluid chamber empties,
the drag between the drive plate and the body is reduced, causing the drive plate to slip. This reduces the
rotational speed of the fan and allows it to ’freewheel’.
12
DESCRIPTION AND OPERATION
| Categories | Land Rover, Land Rover Defender |
|---|---|
| Tags | Land Rover |
| Model Year | 1999, 2000, 2001, 2002 |
| Download File |
|
| Document Type | Workshop Manual |
| Language | English |
| Product Name | Defender |
| Product Brand | Land Rover |
| Document File Type | |
| Publisher | landrover.com |
| Wikipedia's Page | http://en.wikipedia.org/wiki/Land_Rover |
| Copyright | Attribution Non-commercial |
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