SAFARI

4 DLT ENGINE

PROCEDURE FOR CHECKING AN EATON

VISCOUS FAN DRIVE IN A VEHICLEWORKSHOP

This procedure will only give an indication that the fan

drive is cutting in and out, but will not be able to check

the accuracy of the cut in temperature. Please use

this procedure in conjunction with the description on

the operation of the fan drive. All BorgWarner (Eaton)

fan drives work in the same method and have similar

mechanical construction.The only differences are the

size of the fan drive and the external appearance.

Depending on the level of test equipment available

there are several ways of checking if the fan drive is

working correctly.

Using a stroboscope.

With the engine running under no load conditions

for approximately 3minutes, for example at 2,000

rpm, observe the fan drive speed with a

stroboscope. In the disengaged mode the fan

speed should be approximately 800 rpm. By

running for three minutes it will ensure that the

fan drive has pumped out the silicone fluid into

the reservoir and that the fan drive will be in the

cut out ( idle ) condition.

Either

a) Blank the radiator by using a sheet of cardboard

which has a 15 cm hole cut out of it in line with

the centre of the fan drive. This will allow a flow

of air on to the bimetal coil, and the cardboard

will allow the radiator to heat up quicker. Keep a

check on the vehicle temperature gauge and let

the water temperature rise to about 105

C.This

will ensure that the fan drive will engage.

(Depending on the pressure of the water system

let the temperature rise higher)

b) Using a commercial hot air blower, which will

provide a hot air flow of at least 75

C, direct the

air on to the centre of the fan drive through the

radiator. Keep the hot air on for several minutes.

This will cut the fan drive in, and the fan speed

Will increase. It is important that the blower is

powerful to ensure that the hot air reaches the

fan drive at the correct temperature.

Test procedure for fan drive

Once the fan drive has become engaged by

either method in 2, check the fan speed with a

stroboscope . At 2000 rpm input speed the fan

speed should be about 1800 rpm.This may vary

depending on the actual application.

Testing without a stroboscope

Use the same method described in section 2.

but this time listen to the noise level generated

by the fan. With the fan in the idle condition the

noise level should be very low, however when

the fan speed increases in the engaged mode

there will be a significant roar from the fan.

This will dearly indicate if the fan drive is

working.

If the fan drive fails to engage during these

tests there may be something wrong with the

fan drive. The unit should be replaced.