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

 

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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

 

 

 

 

 

 

 

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