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

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 200324

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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 200324

Inspection and adjustment

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CF65/75/85 series

2

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

©

 200324

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

PE ENGINE COOLING SYSTEM

4-6

©

 200324

Inspection and adjustment

6

CF65/75/85 series

2