DAF CF65, CF75, CF85 Series . Manual — part 263

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200324

3-7

Description of components

XE ENGINE COOLING SYSTEM

CF65/75/85 series

2

9

The coil (10) fitted to the drive shaft (4) with

bearings generates a magnetic field. Depending

on the variables mentioned earlier, the PWM

signal to the coil (10) will be adapted. This will

cause changes in the magnetic field and the

valve (9) will be attracted either more or less

frequently.

In static condition all silicone fluid will flow out of

the supply chamber (6), while in dynamic

condition the silicone fluid will remain in the

supply chamber (6) as a result of the centrifugal

force.

When the engine is being started, the fan will

always run for a short time, because the silicone

fluid that has settled at the bottom will be forced

outwards by the centrifugal force. Some of the

silicone fluid will first flow into the working area

(5). The silicone fluid causes friction between the

rotor (3) and the working area (5). As a result, the

difference in rotating speed (slip) between the

working area (5) and the rotor (3) will decrease.

The fan will be more and more engaged.

The silicone fluid will flow through the return

bores (11) of the working area (5), back to the

supply chamber (6).

If the valve (9) releases the opening (8) with a

certain frequency, a certain quantity of silicone

fluid will flow from the supply chamber (6) to the

working area (5). The quantity of silicone fluid

flowing through the working area, determines the

difference in rotating speed (slip) between the

working area (5) and the rotor (3).

If the valve (9) releases the opening (8) with a

higher frequency, the quantity of silicone fluid

flowing through the working area (5) will increase.

The friction between the working area (5) and the

rotor (3) will increase and the difference in

rotating speed (slip) between the working area (5)

and the rotor (3) will decrease.

M201063

10

11

4

3

8

1
2

9

7
6

5

XE ENGINE COOLING SYSTEM

3-8

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Description of components

9

CF65/75/85 series

2

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4-1

Inspection and adjustment

XE ENGINE COOLING SYSTEM

CF65/75/85 series

2

9

4. INSPECTION AND ADJUSTMENT

4.1 PRESSURE TESTING

}

When the coolant is hot, there is

overpressure in the cooling system.

Carefully remove the filler cap to

release the overpressure. Coolant is

a toxic fluid. Contact with the skin

should therefore be avoided. To

avoid damaging the cylinder block;

do not top up a warm engine with

cold coolant.

If this is done when the engine is

warm, any cracks can be spotted

more quickly.

The cooling system can be checked

for leaks with a pressure-test pump.

1.

Open the grille.

2.

Remove the filler cap.

3.

Fill the cooling system to the correct level.

4.

Raise the engine temperature. This need not

be the operating temperature.

5.

Fit a pressure-test pump. Pressure-test the

system at the specified pressure. See

"Technical data".

6.

Check for leakage.

M201192

XE ENGINE COOLING SYSTEM

4-2

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Inspection and adjustment

9

CF65/75/85 series

2

4.2 INSPECTION, THERMOSTAT

1.

Remove the thermostat. See "Removal and

installation".

2.

Inspect the sealing surfaces (A) of the

thermostat housing for damage.

3.

Inspect the oil seal (B) for damage.

4.

Inspect the thermostat seat (C) for damage.

5.

Check whether the thermostat is fully closed.

6.

Place the thermostat in a container filled with

clean water.

7.

Place a thermometer in the container and

heat the water. Check at what temperature

the thermostat starts opening and whether it

fully opens. See "Technical data".

M200594

A

B

C

A

B

C

M200513