DAF CF65, CF75, CF85 Series . Manual — part 235

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4-3

Inspection and adjustment

PE ENGINE COOLING SYSTEM

CF65/75/85 series

2

6

4.3 INSPECTION, VISCOUS FAN CLUTCH

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Do not run the engine in an enclosed

or unventilated area. Make sure

exhaust fumes are properly

extracted. Remain at a safe distance

from rotating and/or moving

components.

During this test, the slip in the viscous fan clutch

is measured while the clutch is not operating.

This test must be carried out when the engine is

"cold" (coolant temperature approximately 50

°C).

Testing with a cold engine
1.

Check the coolant level, and top up as

necessary.

2.

Start the engine and run it at idling speed for

at least 5 minutes.

3.

Then use a digital rev counter to measure the

fan speed at a number of engine speeds

(from idling to maximum engine speed).

During this test procedure, the speed of the

fan should be approx. 600 to 1100 rpm.

This test checks whether the bimetallic strip starts

opening the valve at an operating temperature of

85 - 95

°C.

Testing with a warm engine
1.

Check the coolant level, and top up as

necessary. Be careful when topping up the

coolant of a warm engine.

2.

Remove the front engine encapsulation.

PE ENGINE COOLING SYSTEM

4-4

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Inspection and adjustment

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CF65/75/85 series

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3.

Take a sheet of cardboard with a 100 mm

hole, as shown in the drawing opposite, and

place it in front of the radiator, with the hole

in front of the viscous clutch.

4.

Check that the gearbox is in neutral.

5.

Bring the cooling system to operating

temperature.

6.

Allow the fan drive flange to run at a speed of

1000 rpm.

7.

Then use an optical rev counter to determine

the difference between the rotating speeds

of the fan and the drive flange. The speeds

will differ as a result of slip in the viscous

clutch. For the permissible slip, see

"Technical data". If the slip measured is

greater than that permitted, the viscous fan

clutch must be replaced.

700

100

430

900

M200440

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4-5

Inspection and adjustment

PE ENGINE COOLING SYSTEM

CF65/75/85 series

2

6

4.4 INSPECTION, COOLANT PUMP RADIAL PLAY

1.

Remove the poly-V-belt from the coolant

pump pulley.

2.

Fit a dial gauge as shown in the illustration.

3.

Force the coolant pump pulley downwards

and set the dial gauge to zero.

4.

Pull the coolant pump pulley upwards and

read the dial gauge.

5.

Compare the reading with the technical data.

See "Technical data". If it is more than the

maximum radial play specified in the

technical data, the coolant pump must be

replaced.

M200595

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CF65/75/85 series

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