DAF CF65, CF75, CF85 Series . Manual — part 208

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200351

4-1

Inspection and adjustment

CE-ENGINE COOLING SYSTEM

ΧΦ65/75/85 series

2

3

4. INSPECTION AND ADJUSTMENT

4.1 PRESSURE TESTING

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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

CE-ENGINE COOLING SYSTEM

4-2

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200351

Inspection and adjustment

3

ΧΦ65/75/85 series

2

4.2 INSPECTION, THERMOSTAT

1.

Remove the thermostat. See "Removal and
installation".

2.

Inspect the sealing surfaces of the
thermostat housing for damage.

3.

Check the thermostat seat for damage.

4.

Check whether the thermostat is fully closed.

5.

Place the thermostat in a container filled with
clean water.

6.

Place a thermometer in the container and
heat the water. Check at which temperature
the thermostat opens and whether it opens
fully. See "Technical data".

M200513

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200351

4-3

Inspection and adjustment

CE-ENGINE COOLING SYSTEM

ΧΦ65/75/85 series

2

3

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.
Then use an optical rev counter to measure
the fan speed at different 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.

CE-ENGINE COOLING SYSTEM

4-4

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200351

Inspection and adjustment

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ΧΦ65/75/85 series

2

2.

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.

3.

Check that the gearbox is in neutral.

4.

Bring the cooling system to operating
temperature.

5.

Allow the fan drive flange to run at a speed of
1000 rpm. 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. When the clutch is
fully engaged, the slip must not exceed 10%.
If it is more, the viscous fan clutch must be
replaced.

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550

450

750

300

M201166