Range Rover P38
LAND ROVER V8
3
DESCRIPTION AND OPERATION
ENGINE COOLING - DESCRIPTION
General
The complete cooling system installed in vehicles with
V8 engines incorporates three independent functions:-
Engine (coolant) cooling; Engine oil cooling; Gearbox
oil cooling.
Engine and gearbox oil coolers are mounted in front of
the radiator and linked to their separate systems by
pre-formed pipes and hoses.
The cooling system used on the V8 engine is a
pressurised, by-pass type system which allows
coolant to circulate around the engine block and
heater matrix when the thermostat is closed. With
coolant not passing through the radiator, faster heater
warm-up is promoted which in turn improves
passenger comfort.
A coolant pump is located in a housing at the front of
the engine and is driven by a drive belt. The water
pump is connected into the coolant passages cast into
the cylinder block and pumps coolant from the radiator
through the cylinder block and heater circuit.
A viscous fan is attached to the water pump drive
pulley. The fan is secured by a left hand threaded nut
to the pulley spindle. The fan draws air through the
radiator to assist in cooling when the vehicle is
stationary. The fan rotational speed is controlled
relative to the running temperature of the engine by a
thermostatic valve regulated by a bi-metallic coil.
The cooling system uses a 50/50 mix of anti-freeze
and water.
Thermostat housing
A ’four way’ thermostat housing, located at the bottom
of the fan cowling behind the radiator, is used to link
the main components within the engine cooling
system. The four connections locate the radiator
bottom hose, top hose, by-pass hose and coolant
pump feed hose.
The plastic housing contains a wax element
thermostat. The thermostat and housing are a sealed
unit and cannot be replaced individually. The
thermostat is used to maintain the coolant at the
optimum temperature for efficient combustion and to
aid engine warm-up.
The thermostat is closed at temperatures below
approximately 80
°
C (176
°
F). When the coolant
temperature reaches between 80 to 84
°
C
(176 to 183
°
F) the thermostat starts to open and is
fully open at approximately 96
°
C (204
°
F). In this
condition the full flow of coolant is directed through the
radiator.
Inlet manifold cooling connections
With the thermostat open, coolant leaves the cylinder
block via an outlet pipe and top hose attached to the
front of the inlet manifold. The top hose is connected
to the top of the radiator.
Hot coolant from the cylinder block is also directed
from the inlet manifold via pipes and hoses to the
heater matrix. Coolant is circulated through the heater
matrix at all times when the engine is running.
Plenum chamber - up to 99MY
The plenum chamber is heated with a supply of
coolant from a supply pipe from the inlet manifold to a
plate on the underside of the throttle on the plenum.
The hot coolant prevents the air intake and throttle
linkage from icing. A bleed pipe returns coolant from
the plenum chamber to the expansion tank.
Throttle housing - from 99MY
A tapping from the inlet manifold supplies coolant to
the throttle housing via a hose. The coolant circulates
through a plate attached to the bottom of the throttle
housing and is returned through a plastic bleed pipe to
the expansion tank. The hot coolant heats the throttle
housing preventing ice from forming.