Land Rover Lesson 2 Auto Trans Coolingine Rover Manual

							Cooling System Coolant Flow – Automatic Gearbox Without FBH
Engine CoolingLesson 2 – Powertrain
137Technical Training (G421101) 
						

							Cooling System Coolant Flow – Automatic Gearbox With FBH
When the engine is running the coolant pump is driven
by the ancillary drive belt. This forces coolant to
circulate around the engine and heater, while the
thermostat and bypass valve are shut. As the temperature
and pressure increases the bypass valve is forced open
allowing coolant to circulate through the bypass valve.
When the temperature reaches 82°C (180°F) the main
thermostat begins to open, allowing coolant to circulate
through the main radiator. As the thermostat
progressively opens (fully open at 95°C (203°F)), the
bypass valve progressively closes forcing any coolant
through the heater or radiator. Once coolant is allowed
to circulate through the radiator, the transmission fluid
(automatic models only) and fuel coolers begin to
receive coolant flow.
The increased coolant volume, created by heat
expansion, is directed to the expansion tank through a
bleed hose from the top of the radiator. The expansion
(G421101) Technical Training138
Lesson 2 – PowertrainEngine Cooling 
						

							tank has an outlet hose which is connected into the
coolant circuit. This outlet hose returns the coolant to
the system when the engine cools.
Coolant flows through the radiator from the top right
hand tank to the bottom left hand tank and is cooled by
air passing through the matrix. The temperature of the
cooling system is monitored by the ECM via the Engine
Coolant temperature (ECT) sensor located in the
cylinder head. The ECM uses signals from this sensor
to control the cooling fan operation and adjust fuelling
according to engine temperature.
To control the cooling fan, the ECM sends a Pulse
Width Modulated (PWM) signal to the cooling fan
module (integral to the ECM). The frequency of the
PWM signal is used by the cooling fan module to
determine the output voltage supplied to the fan motor.
The ECM varies the duty cycle of the PWM signal
between 0 and 100% to vary the fan speed. If the PWM
signal is outside the 0 to 100% range, the cooling fan
module interprets the signal as an open or short circuit
and runs the fans at maximum speed to ensure the engine
and gearbox do not overheat.
The ECM operates the fan in response to inputs from
the ECT sensor, the transmission oil temperature sensor,
the charge air temperature sensor, the A/C switch and
the A/C pressure sensor.
The speed of the cooling fan is also influenced by
vehicle road speed. The ECM adjusts the speed of the
cooling fans, to compensate for the ram effect of vehicle
speed, using the Controller Area Network (CAN) road
speed signal received from the Anti-lock Braking
System (ABS) module.
Pressure Relief Thermostat (PRT)
The thermostat is exposed to 85% hot coolant from the
engine on one side and 15% cold coolant returning from
the radiator bottom hose on the other side. This allows
the thermostat to react to the ambient conditions and
provide coolant control for both winter and summer use.
Hot coolant from the engine passes via holes in the
by-pass flow valve into a tube which surrounds 85% of
the thermostat sensitive area. Cold coolant from the
radiator conducts through the remaining 15% of the
sensitive area. In cold ambient conditions, the engine
temperature is raised by approximately 10°C (50°F) to
compensate for the heat loss of 15% exposure to the
cold coolant returning from the bottom hose. This
improves heater performance and engine warm-up.
The by-pass flow valve is held closed by a light spring
and operates to further assists engine and heater
warm-up. When the main valve is closed and the engine
speed is at idle, the coolant pump does not produce
sufficient flow and pressure to overcome the spring and
open the valve. In this condition the valve prevents
coolant circulating through the by-pass circuit and
directs coolant through the heater matrix only. This
provides a higher flow of coolant through the heater
matrix improving passenger comfort in cold conditions.
When the engine speed increases above idle, the coolant
pump produces a greater flow and pressure than the
heater circuit can accommodate. The build up of
pressure acts on the flow valve, overcoming the spring
pressure, opening the valve and relieving the pressure
in the heater circuit. The valve then modulates to provide
maximum coolant flow through the heater matrix and
allowing excess coolant to flow into the by-pass circuit
to provide the engines cooling requirements at higher
engine speeds. The thermostat then regulates the flow
through the radiator to maintain the engine at the
optimum temperature. Maximum opening of the
thermostat, and therefore maximum flow through the
radiator, occurs if the coolant temperature reaches 95°C
(203°F).
Engine CoolingLesson 2 – Powertrain
139Technical Training (G421101) 
						

							Exhaust Gas Recirculation Component Location
Fuel rail damper1
Vacuum control hoses2
Exhaust manifold to Exhaust Gas Recirculation
(EGR) hose
3
Exhaust manifold4
ESM valve5
Engine emissions on the V6 petrol engine are controlled
by the Engine Control Module (ECM). The engine
emission control system comprises:
•EGR system
•Crankcase emission system
(G421133) Technical Training166
Lesson 2 – PowertrainEngine Emission Control 
						

							EGR SYSTEM
ESM Valve
The EGR System Module (ESM) valve is located on
the intake manifold with a pipe connecting the exhaust
manifold to the valve. Connection between the sensor
and the harness is via a six-way connector. The ESM
valve is electrically controlled by a Pulse Width
Modulated (PWM) signal. The ESM valve allows
burned exhaust gas to be recirculated back into the
engine. Since exhaust gas has much less oxygen than
air, it is basically inert. The exhaust gas takes the place
of air in the cylinder and reduces combustion
temperature. As the combustion temperature is reduced,
so are the oxides of nitrogen (NOx) emissions.
The ESM valve has an integrated Differential Pressure
Feedback-Electronic/Manifold Absolute Pressure
(DPFE/MAP) sensor. This pressure transducer monitors
the pressure differential on either side of an orifice in
the ESM system flow path and then transmits that
information to the ECM. The pressure drop measured
across this orifice is used to estimate the flow rate of
recirculated exhaust gas. An Electronic Vacuum
Regulator (EVR) is used to control the vacuum signal
to the ESM valve based on the electrical signal from
the ECM. The ECM monitors the ESM level based on
the feedback from the DPFE/MAP sensor, which creates
a closed loop system.
Engine Emission ControlLesson 2 – Powertrain
167Technical Training (G421133) 
						

							CRANKCASE VENTILATION SYSTEM
Crankcase Ventilation System Component Location
Crankcase Ventilation ( CCV ) Hose and cam
lock connector
1
Engine to evaporative emissions control tube2
Evaporative emissions control valve3
Crankcase Ventilation (CCV) hose4
Positive Crankcase Ventilation(PCV) hose and
PCV valve
5
PCV jump lead with integral thermistor6
(G421133) Technical Training168
Lesson 2 – PowertrainEngine Emission Control 
						

							Positive Crankcase Ventilation (PCV) Valve
The crankcase ventilation system comprises:
•Positive Crankcase Ventilation (PCV) valve
•Positive Crankcase Ventilation (PCV) hose
•Crankcase Ventilation (CCV) hose
The PCV is an electrically heated control valve that
allows the gas from left hand cylinder head to flow into
the air intake. The PCV valve is electrically heated to
allow it to remain operational in cold climates. The PCV
heater power is fed from the fuel pump relay, therefore
heating is always active while the engine is running.
The current supplied is internally regulated by the PCV.
Engine Emission ControlLesson 2 – Powertrain
169Technical Training (G421133) 
						

							EXHAUST GAS RECIRCULATION (EGR)
EGR and Crankcase Ventilation Component Location
Full load tube1
Pressure Control Valve (PCV)2
Part load tube3
EGR tube4
EGR valve5
Electric throttle6
(G421134) Technical Training170
Lesson 2 – PowertrainEngine Emission Control 
						

							The EGR system is controlled by a PWM signal from
the ECM. The system comprises an EGR valve and a
gas transfer pipe.
The EGR valve comprises a 4 pole stepper motor with
an integral cooler unit which is mounted on the side of
the induction elbow. The EGR valve is cooled by the
return coolant flow from the electric throttle.
The EGR valve is connected to the LH exhaust manifold
via the gas transfer pipe.
CRANKCASE VENTILATION
The V8 engine is ventilated through a part load and a
full load breather.
The part load breather is a flexible composite hose
connected between the PCV valve mounted above the
oil separator in the bank A camshaft cover and the
induction elbow. The Positive Crankcase Ventilation
(PCV) valve prevents reverse flow into the crankcase.
The full load breather is a flexible hose connected
between the oil separator in the bank B camshaft cover
and the air intake duct.
The ends of the breather hoses incorporate quick release
connectors.
The oil separators consist of wire gauze packed into an
open ended enclosure below the breather outlet.
Engine Emission ControlLesson 2 – Powertrain
171Technical Training (G421134) 
						

							EGR modulator/ cooler assembly1
Electric throttle2
EGR to electric throttle tube3
EGR cooler4
EGR modulator valve5
EGR modulator solenoid valve6
EGR coolant hoses7
EGR SYSTEM
The EGR system comprises:
•EGR modulator x 2
•EGR cooler x 2
•Associated connecting pipes
(G421135) Technical Training172
Lesson 2 – PowertrainEngine Emission Control