DAF CF65, CF75, CF85 Series . Manual — part 261

©

200324

2-3

General

XE ENGINE COOLING SYSTEM

CF65/75/85 series

2

9

2.2 SYSTEM DESCRIPTION, COOLING SYSTEM

From the delivery side of the water pump (1), the

coolant is directed to the cylinder block (2) via an

opening at the back of the coolant pump.

The coolant flows through the cylinder block up to

the cylinder heads (3).

The coolant leaves the cylinder heads through

the coolant collector pipe (4) (A), which takes it to

the thermostat housing (5).

If an intarder (13) or automatic gearbox (13) is

fitted, the coolant leaving the cylinder heads flows

via the coolant collector pipe (4) (B) to the intarder

or the automatic gearbox.

From the intarder or automatic gearbox, the

coolant then flows via the coolant collector pipe

(B) to the thermostat housing (5).

Depending on the coolant temperature, the

thermostat distributes the coolant flow to the

radiator (6) or back to the coolant pump (1).

The coolant transported to the radiator enters the

radiator at the top, and leaves the radiator at the

bottom.

From the bottom of the radiator, the coolant is

returned to the coolant pump, via the coolant

return pipe.

M201279

Heater unit

Thermostat

Coolantpump

Cylinderblock

Cylinderhead

Radiator

6

1

5

12

13

15

10

8

14

3

4

2

3

9

7

11

Cylinderhead

Coolantpipe

Oilcooler

Compressor

Coolantpipe

Retarder

Automatic transmission

Coolant

filter

Non

return

valve

Auxiliary

cab heater

Reservoir

M201038

A

B

XE ENGINE COOLING SYSTEM

2-4

©

200324

General

9

CF65/75/85 series

2

The header tank (7) has four connections. On the

top of the radiator, there is a bleed pipe which is

linked to connection 3 of the header tank.

Connections 1 and 2 of the header tank are linked

to the coolant collector pipe by bleed pipes. If no

intarder or automatic gearbox is fitted, one of the

connections will be sealed.

Connection 4 enables siphoning of the coolant

between the header tank and the engine when

the coolant temperature increases.

Connection 4 is linked together with the heater

return pipe to the coolant return pipe leading to

the coolant pump.

From the cylinder block, some of the coolant

flows through the oil cooler (8). From the oil

cooler, the coolant returns to the coolant pump

through a pipe via the coolant return pipe.

From the cylinder block, some of the coolant

flows through the air compressor (9). From the air

compressor, the coolant returns to the coolant

pump via a pipe.

From the coolant collector pipe, a pipe runs to the

cab heater (11). The heater return pipe is linked

together with the header tank pipe to the coolant

return pipe leading to the coolant pump.

If a cab heater (15) s fitted, a non-return valve

(10) is fitted in the heater supply pipe. It has two

connections. Connection (1) is for the cab heater

supply pipe. Connection (2) is for the cab heater

discharge pipe.

Note:

Fit the non-return valve with the arrow pointing in

the flow direction of the coolant.

M201034

4

1 2

3

1

2

M201035

©

200324

3-1

Description of components

XE ENGINE COOLING SYSTEM

CF65/75/85 series

2

9

3. DESCRIPTION OF COMPONENTS

3.1 PRESSURE CAP

The pressure cap is fitted to the header tank by

means of a threaded connection.

The pressure cap has two valves: a pressure

relief valve (1) and a vacuum relief valve (2).

Overpressure
As a result of the rising coolant temperature, the

pressure in the cooling system will increase. If the

pressure in the cooling system becomes too high,

the pressure relief valve (1) will open against the

pressure of the spring.

Underpressure
If the coolant temperature drops, the pressure in

the cooling system will decrease. If the pressure

in the cooling system becomes too low, the

vacuum relief valve (2) will be opened.

2

1

A

B

M201036

XE ENGINE COOLING SYSTEM

3-2

©

200324

Description of components

9

CF65/75/85 series

2

3.2 THERMOSTAT

The coolant enters the thermostat housing from

the coolant collector pipe at the back and then

flows through the thermostat. Depending on the

coolant temperature and the corresponding

position of the thermostat, there are three

possibilities:

Thermostat closed

The coolant has not yet reached the thermostat

opening temperature.

The supply channel (B) to the radiator is

completely closed.

The coolant flows directly to the coolant pump

through a bypass (A) and the coolant pump

returns the coolant to the cylinder block.

Thermostat starts opening

The coolant has reached the thermostat opening

temperature.

The supply channel (B) to the radiator is opened

and the bypass (A) is partially closed.

Now coolant will flow both through the supply

channel (B) to the radiator and through the

bypass (A) directly to the coolant pump.

Thermostat fully opened

The temperature of the coolant has further

increased. The supply channel (B) to the radiator

is fully opened and the bypass (A) is fully closed.

All the coolant now flows through the supply

channel (B) to the radiator, where it is cooled

before flowing back to the coolant pump.

In the event of excessive coolant temperatures,

removing the thermostat as an emergency

solution is not permitted.

If the thermostat is removed from the engine,

uncooled coolant will flow to the coolant pump

through the bypass (A). As a result, the coolant

temperature will continue to rise.

M200547

A

B

A

B

A

B