Range Rover P38
LAND ROVER V8
9
DESCRIPTION AND OPERATION
ENGINE COOLING - OPERATION
Coolant flow
Engine warm up - up to 99MY
When the engine is started from cold, the thermostat,
integral in the housing, prevents any coolant
circulation through the radiator by closing off the
supply from the radiator bottom hose.
During engine warm up, the water pump moves
coolant around the cylinders to the rear of the engine
block and along the galleries in both cylinder banks.
At the rear of the cylinder block the coolant rises
through a large port in both cylinder head/block joint
faces to the inlet manifold.
From the manifold, the coolant flow is divided between
the by-pass hose, the heater feed hose and the
plenum chamber feed pipe. The heater feed hose
supplies the heater matrix, located within the
distribution unit of the heating and ventilation system.
The coolant is then carried, via the heater return hose,
back to the thermostat housing to complete the cycle.
The heater matrix acts as a heat exchanger reducing
coolant temperature as it passes through the matrix.
With the thermostat closed and coolant flowing around
the by-pass circuit, the cooling system is operating at
maximum heater performance.
The plenum chamber is heated by a flow of coolant
through the feed pipe from the inlet manifold. A bleed
pipe returns the coolant from the plenum chamber
across the engine to the expansion tank.
Engine hot - up to 99MY
When normal engine running temperature is reached,
the main valve of the thermostat opens and a
secondary valve closes the bypass port. With the
thermostat open, coolant is circulated through the top
hose to the radiator.
The air flowing between the tubes cools the coolant as
it passes through the radiator. A controlled flow of the
lower temperature coolant is drawn from the base of
the radiator, through the bottom hose, by the water
pump and blended with hot coolant returning from the
heater matrix. Coolant circulation through cylinder
block and cylinder heads to the heater matrix and
plenum chamber remains the same.
Coolant is drawn from the base of the radiator,
through the bottom hose, by the water pump. Coolant
circulation through the cylinder block and cylinder
heads to the heater matrix and plenum chamber
remains the same.
An integral bleed pipe connects the top of the radiator
to the expansion tank and aids bleeding of air from the
coolant system. The expansion tank cap contains a
pressure valve which allows excessive pressure and
coolant to vent to the overflow pipe if the system has
been overfilled.
Engine warm up - from 99MY
When the engine is started from cold, the thermostat,
integral in the housing, prevents any coolant
circulation through the radiator by closing off the
supply from the radiator bottom hose.
During engine warm up, the water pump moves
coolant around the cylinders to the rear of the engine
block and along the galleries in both cylinder banks.
At the rear of the cylinder block the coolant rises
through a large port in both cylinder head/block joint
faces to the inlet manifold.
From the manifold, the coolant flow is divided between
the outlet pipe and the top hose by-pass connection to
the thermostat housing, the heater inlet pipe and hose
and the throttle housing inlet hose.
The heater inlet pipe and hose supply the heater
matrix, located within the distribution unit of the
heating and ventilation system. The coolant is then
carried, via the heater return hose and pipe, back to
the thermostat housing to complete the cycle.
The heater matrix acts as a heat exchanger reducing
coolant temperature as it passes through the matrix.
With the thermostat closed and coolant flowing around
the by-pass circuit, the cooling system is operating at
maximum heater performance.
The throttle housing inlet hose allows coolant to flow
from the inlet manifold to the plate attached to the
bottom of the throttle housing. A return pipe directs
coolant flow from the throttle housing to the expansion
tank.