1999 LAND ROVER DEFENDER engine coolant

ENGINE MANAGEMENT SYSTEM
11
DESCRIPTION AND OPERATION SENSOR - ENGINE COOLANT TEMPERATURE
(ECT)
The ECT sensor is located in the coolant outlet elbow on top of the engine. It provides the ECM with engine
coolant temperature information. The ECM uses this information for the following functions:
Fuelling calculations.
Temperature gauge.
To limit engine operation if coolant temperature is to high.
Cooling fan operation.
Glow plug operating time.
The ECT works as an NTC sensor. As temperature rises, the resistance in the sensor decreases, as temperature
decreases, the resistance in the sensor increases. The ECM compares the voltage signal to stored values and
compensates fuel delivery to ensure optimum driveability at all times.
Inputs / Outputs
The ECT sensor (C0169-2) is provided a feed by the ECM (C0158-7) on a pink/green wire. The sensor is provided
an earth path (C0169-1) via the ECM (C0158-18) on a pink/black wire.
The ECT can fail or supply an incorrect signal if one or more of the following occurs:
Sensor open circuit.
Short circuit to vehicle supply.
Short circuit to vehicle earth.
Incorrect mechanical fitting.
Signal fixed above 40°C (104°F) not detected.
Signal fixed below 40°C (104°F) not detected.
In the event of an ECT sensor failure, any of the following symptoms may be observed:
Difficult cold start.
Difficult hot start.
Driveability concerns.
Instrument pack warning lamp illuminated.
Temperature gauge reads excessively hot.
Temperature gauge reads excessively cold.
In the event of a component failure the ECM calculates coolant temperature from the fuel temperature signal. If
this occurs, the limit of engine operation if coolant temperature becomes too high becomes inoperative.
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18ENGINE MANAGEMENT SYSTEM
24
DESCRIPTION AND OPERATION GLOW PLUGS
The 4 glow plugs are located in the engine block on the inlet side, in cylinders 1 to 4. Cylinder 5 has no glow plug.
The glow plugs are a vital part of the engine starting strategy. The purpose of the glow plugs are:
Assist cold engine start.
Reduce exhaust emissions at low engine load/speed.
The main part of the glow plug is a tubular heating element that protrudes into the combustion chamber of the
engine.The heating element contains a spiral filament that is encased in magnesium oxide powder. At the tip of
the tubular heating element is the heater coil. Behind the heater coil and connected in series is a control coil. The
control coil regulates the heater coil to ensure that it does not overheat and cause a possible failure. The glow
plug circuit has its own control relay, located underneath the RH front seat.
Pre-heat is the length of time the glow plugs operate prior to engine cranking. The ECM controls the pre-heat time
of the glow plugs based on battery voltage and coolant temperature information via the glow plug relay.
Post-heat is the length of time the glow plugs operate after the engine starts. The ECM controls the post-heat time
based upon ECT information. If the ECT fails the ECM will operate pre-post heat time strategies with default
values from its memory. In this case, the engine will be difficult to start.
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18ENGINE MANAGEMENT SYSTEM
28
DESCRIPTION AND OPERATION OPERATION
Engine Management
The ECM controls the operation of the engine using stored information within its memory. This guarantees
optimum performance from the engine in terms of torque delivery, fuel consumption and exhaust emissions in all
operating conditions, while still giving optimum driveability.
The ECM will receive information from its sensors under all operating conditions, especially during:
Cold starting.
Hot starting.
Idle.
Wide open throttle.
Acceleration.
Adaptive strategy.
Backup strategy for sensor failures.
The ECM receives information from various sensors to determine the current operating state of the engine. The
ECM then refers this information to stored values in its memory and makes any necessary changes to optimise
air/fuel mixture and fuel injection timing. The ECM controls the air/fuel mixture and fuel injection timing via the
Electronic Unit Injectors (EUI), by the length of time the EUI’s are to inject fuel into the cylinder. This is a rolling
process and is called adaptive strategy. By using this adaptive strategy the ECM is able to control the engine to
give optimum driveability under all operating conditions.
During cold start conditions the ECM uses ECT information to allow more fuel to be injected into the cylinders.
This, combined with the glow plug timing strategy supplied by the ECM, facilitates good cold starting.
During hot start conditions, the ECM uses ECT and FT information to implement the optimum fuelling strategy to
facilitate good hot starting.
During idle and wide open throttle conditions, the ECM uses mapped information within its memory to respond to
input information from the TP sensor to implement the optimum fuelling strategy to facilitate idle and wide open
throttle.
To achieve an adaptive strategy for acceleration, the ECM uses input information from the CKP sensor, the TP
sensor, the ECT sensor, the MAP/IAT sensor, and the FT sensor. This is compared to mapped information within
its memory to implement the optimum fuelling strategy to facilitate acceleration.
Fuel Delivery / Injection Control
The fuel delivery/injection control delivers a precise amount of finely atomised fuel to mix with the air in the
combustion chamber to create a controlled explosion. To precisely control fuel delivery and control fuel injection,
the following input conditions must be met:
CKP information.
Injection timing map information.
FT information.
ECT information.
The ECM monitors the conditions required for optimum combustion of fuel in the cylinder from the various sensors
around the engine and then compares it against stored information. From this calculation, the ECM can adjust the
quantity and timing of the fuel being delivered into the cylinder. The ECM uses CKP information as follows:
To calculate engine speed.
To determine engine crankshaft position.
Engine speed and crankshaft position allows the ECM to determine fuel injection timing.
The ECM also uses ECT and FT information to allow optimum fuel delivery and injection control for all engine
coolant and fuel temperatures.
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ENGINE MANAGEMENT SYSTEM
1
REPAIR ENGINE CONTROL MODULE (ECM)
Service repair no - 18.30.03
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery negative lead.
3.Remove RH seat cushion, release clip and
remove ECM access panel.
4.Remove 3 bolts, release ECM and disconnect 2
multiplugs. Remove ECM.
Refit
5.Position new ECM and connect multiplugs.
6.Fit ECM and tighten bolts.
7.Fit access panel and RH seat cushion.
8.Reconnect battery negative lead.
9.Fit battery cover and secure with fixings.SENSOR - ENGINE COOLANT TEMPERATURE
(ECT)
Service repair no - 18.30.10
Remove
1.Disconnect battery negative lead.
2.Remove spring clip and disconnect ECT sensor
multiplug.
3.Position cloth around ECT sensor to absorb
coolant spillage.
4.Remove ECT sensor.
5.Remove sealing washer and discard.
Refit
6.Clean sealing washer, sensor threads and
sensor location.
7.Coat sensor threads with Loctite 577 and fit new
sealing washer.
8.Fit ECT sensor and tighten to20 Nm (14 lbf.ft).
9.Fit spring clip to multiplug and connect multiplug
to ECT sensor.
10.Top up cooling system.
11.Run engine to normal operating temperature.
Check for leaks around ECT sensor.
12.Reconnect battery negative lead.
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19FUEL SYSTEM
4
REPAIR ELEMENT - FUEL FILTER
Service repair no - 19.25.07
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery negative lead.
3.Raise rear of vehicle.
WARNING: Support on safety stands.
4.Release fixing and remove fuel filter cover.
5.Clean area around fuel filter.
6.Disconnect multiplug from filter element.
7.Remove fuel filter element.
Refit
8.Clean fuel filter and mating face.
9.Fit new fuel filter element and connect multiplug.
10.Position fuel filter cover and secure with fixing.
11.Remove stand(s) and lower vehicle.
12.Reconnect battery negative lead.
13.Fit and secure battery cover.COOLER - FUEL
Service repair no - 19.25.30
Remove
1.Remove 3 bolts and remove engine acoustic
cover.
2.Remove battery cover.
3.Disconnect battery negative lead.
4.Drain cooling system.See COOLING
SYSTEM, Adjustment.
5.Release 3 clips and disconnect 3 coolant hoses
from fuel cooler.
6.Release 2 fuel hoses from fuel cooler.
CAUTION: Plug the connections.
7.Release vacuum pipe clip from fuel cooler.
8.Remove 4 bolts securing fuel cooler to inlet
manifold and remove cooler.
Refit
9.Clean fuel hose connections.
10.Position fuel cooler to inlet manifold. Apply
Loctite 242 to bolts and tighten to18 Nm (13
lbf.ft).
11.Connect fuel hoses.
12.Connect coolant hoses, secure with clips.
13.Secure vacuum hose to fuel cooler.
14.Refill cooling system.See COOLING SYSTEM,
Adjustment.
15.Fit engine acoustic cover and secure with bolts.
16.Reconnect battery negative lead.
17.Fit battery cover.
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COOLING SYSTEM
3
DESCRIPTION AND OPERATION
NOTE: Inset A shows differences for Pre
EU3 models
1.Pressure cap
2.Overflow pipe
3.Heater return hose
4.Heater matrix
5.Heater inlet hose
6.Oil cooler return pipe - EU3 models
7.Connecting hose
8.Oil cooler housing assembly
9.Heater inlet pipe
10.Connecting hose
11.Outlet housing
12.Engine Coolant Temperature (ECT) sensor
13.Bleed screw
14.Radiator top hose
15.Radiator - upper
16.Intercooler
17.Gearbox oil cooler
18.Radiator - lower
19.Viscous fan
20.Drain plug
21.Connecting hose
22.Fuel cooler feed hose
23.Radiator bottom hose
24.Thermostat housing
25.Connecting hose
26.Coolant pump feed pipe
27.Coolant by-pass pipe
28.Radiator bleed pipe
29.Connecting hose
30.Coolant pump
31.Fuel cooler
32.Heater/expansion tank return hose
33.Expansion tank
34.EGR Cooler - EU3 models
35.Connecting hose - EU3 models
36.Connecting hose - EU3 models
37.Hose - EGR Cooler to oil cooler return pipe -
EU3 models
38.Radiator lower feed hose - Pre EU3 models
39.Oil cooler return pipe - Pre EU3 models
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COOLING SYSTEM
5
DESCRIPTION AND OPERATION A - EU 3 Models
B- Pre EU3 Models
GENERAL
The cooling system used on the Diesel engine is a pressure relief by-pass type system which allows coolant to
circulate around the engine block and heater circuit when the thermostat is closed. With coolant not passing
through the by-pass or the radiator promotes faster heater warm-up which in turn improves passenger comfort.
A coolant pump is mounted on a casting behind the PAS pump and is driven from the PAS pump at crankshaft
speed by the auxiliary drive belt. The pump mounting casting connects with passages in the cylinder block and
pumps coolant from the radiator through the cylinder block.
A viscous fan is attached to an idler pulley at the front of the engine. The fan is attached to a threaded spigot on
the pulley with a right hand threaded nut. 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 plastic thermostat housing is located behind the radiator. The housing has three connections which locate the
radiator bottom hose, top hose and coolant pump feed pipe. The housing contains a wax element thermostat and
a spring loaded by-pass flow valve.
Thermostat - Main valve
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 82°C (179°F). When the coolant
temperature reaches approximately 82°C 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.
The thermostat is exposed to 90% hot coolant from the engine on one side and 10% cold coolant returning from
the radiator bottom hose on the other side.
Hot coolant from the engine passes from the by-pass pipe through four sensing holes in the flow valve into a tube
surrounding 90% of the thermostat sensitive area. Cold coolant returning from the radiator, cooled by the ambient
air, conducts through 10% of the thermostat sensitive area.
In cold ambient temperatures, the engine temperature is raised approximately 10°C (50°F) to compensate for the
heat loss of 10% exposure to the cold coolant returning from the radiator bottom hose.
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26COOLING SYSTEM
6
DESCRIPTION AND OPERATION By-pass flow valve
The by-pass flow valve is held closed by a light spring. It operates to further aid heater warm-up. When the main
valve is closed and the engine speed is below 1500 rev/min, the coolant pump does not produce sufficient flow
and pressure to open the valve. In this condition the valve prevents coolant circulating through the by-pass circuit
and forces the coolant through the heater matrix only. This provides a higher flow of warm coolant through the
heater matrix to improve passenger comfort in cold conditions.
When the engine speed increases above 1500 rev/min the coolant pump produces a greater flow and pressure
than the heater circuit can take. The pressure acts on the flow valve and overcomes the valve spring pressure,
opening the valve and limiting the pressure in the heater circuit. The valve modulates to provide maximum coolant
flow through the heater matrix and yet allowing excess coolant to flow into the by-pass circuit to provide the
engines cooling needs at higher engine rev/min.
Outlet Housing
A cast aluminium outlet housing is attached to the cylinder head with three bolts and sealed with a gasket. Coolant
leaves the engine through the outlet housing and is directed through a hose to the heater matrix, the radiator or
the by-pass circuit.
An Engine Coolant Temperature (ECT) sensor is installed in a threaded port on the side of the outlet housing. The
sensor monitors coolant temperature emerging from the engine and sends signals to the Engine Control Module
(ECM) for engine management and temperature gauge operation.
Expansion Tank
The expansion tank is located in the engine compartment. The tank is made from moulded plastic and attached to
brackets on the right hand inner wing. A maximum coolant when cold level is moulded onto the tank.
Excess coolant created by heat expansion is returned to the expansion tank from the radiator bleed pipe at the top
of the radiator. An outlet pipe is connected into the coolant pump feed hose and replaces the coolant displaced by
heat expansion into the system when the engine is cool.
The expansion tank is fitted with a sealed pressure cap. The cap contains a pressure relief valve which opens to
allow excessive pressure and coolant to vent through the overflow pipe. The relief valve is open at a pressure of
1.4 bar (20 lbf.in) and above.
Heater Matrix
The heater matrix is fitted in the heater assembly inside the passenger compartment. Two pipes pass through the
bulkhead into the engine compartment and provide coolant flow to and from the matrix. The pipes from the
bulkhead are connected to the matrix, sealed with’O’rings and clamped with circular rings.
The matrix is constructed from aluminium with two end tanks interconnected with tubes. Aluminium fins are
located between the tubes and conduct heat from the hot coolant flowing through the tubes. Air from the heater
assembly is warmed as it passes through the matrix fins. The warm air is then distributed in to the passenger
compartment as required.
When the engine is running, coolant from the engine is constantly circulated through the heater matrix.
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