Jaguar XJ (X350). Manual — part 591

•

Radiator

•

Coolant pressure cap

•

Thermostat

•

Water pump

•

Electric cooling fan

•

Coolant expansion tank

•

Engine oil cooler

Water Pump

The water pump is of a conventional design and is driven by the crankshaft pulley through the

accessory drive belt. The water pump belt tension is maintained by an automatic drive belt tensioner.

<<303-05>>

Thermostat

The thermostat is located in the thermostat housing and allows rapid engine warm-up by restricting

coolant flow through the radiator below 82°C (180°F). The thermostat also assists in keeping the

engine operating temperature within predetermined limits. On the 4.2L supercharged engine the

thermostat begins to open at 84°C (183°F) and is fully open at 98°C (208°F), on the 3.5L or 4.2L and

3.0L engine the thermostat begins to open at 88°C - 92°C (190°F - 198°F) and is fully open at 102°C

(216°F).

When the engine is cold and the thermostat is closed, coolant flows from the water pump through

the engine. It then returns to the water pump through the upper coolant hose.

When the engine is warm and the thermostat is open, coolant flows into the radiator through the

upper coolant hose. It then returns to the water pump from the radiator through the lower coolant

hose and engine oil cooler.

The heater core is on a parallel circuit and is unaffected by the position of the thermostat.

Radiator

The radiator is of aluminium construction with plastic end tanks. Foam seals are fitted to the radiator

to prevent the cooling air from by passing the radiator core. A coolant drain plug is provided in the

lower coolant end tank of the radiator for the draining of the coolant. The cooling fan shroud is

attached to the radiator.

Cooling Fan

A single, variable speed cooling fan motor is attached to a fan shroud located behind the radiator.

The speed is determined by the Engine Coolant Temperature (ECT) and the air conditioning pressure

and transmission oil temperature.

Under hot operating conditions, the fan may continue to operate for four minutes after the engine

has been switched off.

Engine Block Heater

For vehicle markets subject to very cold climate conditions, an engine block heater for connection to

an external mains power supply, is fitted in place of the engine block drain plug.

Coolant Recovery System

A pressurized coolant expansion tank system is used which continuously separates the air from the

cooling system and replenishes the system through the coolant expansion tank outlet hose, attached

to the heater return hose.

A continuous vent from the engine and radiator to the coolant expansion tank prevents air locks

from forming in the cooling system.

Manual bleed points are provided on the coolant reservoir.

The coolant expansion tank serves as the location for:

•

service fill.

•

coolant expansion during warm-up.

•

air separation during operation.

•

system pressurization by the coolant pressure cap.

The coolant expansion tank is designed to have approximately 0.5 to 1 liter of air when cold to allow

for coolant expansion.

Engine Oil Cooler

The engine oil cooler is a Modine oil to water type. The oil cooler on the 3.0L engine is fitted to the

oil filter housing. The oil cooler on the 3.5L or 4.2L engine is located at the front of the engine and is

fitted between the oil filter housing and the oil filter. The oil cooler on the 4.2L engine with a

supercharger is fitted behind the front bumper on the front of the cooling pack.

The coolant supply for the engine oil cooler is through the radiator bottom hose.

Engine Coolant

The long life engine coolant is formulated to last for five years or 240,000 km (150,000 miles). The

coolant is silicate free and orange in color. The long life engine coolant must not be mixed with

conventional engine coolant.

www.

Vehicles with 3.0L engine

Item

Part Number

Description

1

—

Water pump

2

—

Throttle body

3

—

V6 engine

4

—

Heater core

5

—

Engine oil cooler

6

—

Thermostat

7

—

Lower hose

8

—

Radiator

9

—

Coolant expansion tank

10

—

Upper hose

Vehicles with 3.5L or 4.2L engine

Item

Part Number

Description

1

—

EGR valve

2

—

Throttle body

3

—

Heater core

4

—

Water pump

5

—

Engine bank (left-hand)

www.