DAF CF65, CF75, CF85 Series . Manual - part 206

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 200351

2-1

General

CE-ENGINE COOLING SYSTEM

ΧΦ65/75/85 series

2

3

2. GENERAL

2.1 SYSTEM DESCRIPTION, COOLING SYSTEM

The cooling system consists of a water pump, a 
radiator, a header tank, an oil cooler, an air 
compressor, a thermostat housing with one 
thermostat and pipes.

The water pump is located below the thermostat 
in the engine block.
The thermostat housing is part of the cylinder 
head.
From the delivery side of the water pump, the 
coolant is directed to the oil cooler via an opening 
at the back of the water pump. Afterwards the 
coolant flows to the cylinder block.
The coolant flows through the cylinder block, 
along the cylinder liners, and up to the cylinder 
heads.

The coolant leaves the cylinder heads through 
the thermostat housing.

Depending on the coolant temperature, the 
thermostat distributes the coolant flow to the 
radiator or back to the water pump.
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 water pump, via the return pipe.

The connection pipe to the header tank is also 
connected to the return pipe from the radiator. 
When the coolant heats up, it flows to the header 
tank. When the coolant cools down, it will flow 
back from the header tank.

The oil cooler is not only intended to cool the 
lubricating oil, but also to heat the lubricating oil in 
a "cold" engine.

From the cylinder block, some of the coolant 
flows through the air compressor.
From the air compressor, the coolant is returned 
to the engine block via a pipe.

The pipe which takes the coolant to the cab 
heater is connected to the cylinder head. From 
the heater, the coolant is returned to the water 
pump via a pipe.

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General

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ΧΦ65/75/85 series

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Description of components

CE-ENGINE COOLING SYSTEM

ΧΦ65/75/85 series

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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.

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1

A

B

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Description of components

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ΧΦ65/75/85 series

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3.2 THERMOSTAT

Operation, thermostat
Coming from the cylinder head, the coolant 
passes 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 opening 
temperature of the thermostat (1).
The supply channel (B) to the radiator is 
completely closed.
The coolant flows directly to the water pump 
through a bypass (A) and the water pump returns 
the coolant to the cylinder block.

Thermostat starts opening
The coolant has reached the opening 
temperature of the thermostat (1).
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 directly to the 
water pump through the bypass channel (A).

1

A

B

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