Land Rover Discovery: Oil Cooler

1. Engine coolant outlet
2. Engine coolant inlet from cylinder block
3. Oil pressure outlet to cylinder block
4. Oil pressure inlet / Anti-drain valve

The engine oil cooler is located on the side of the cylinder block, below the turbocharger and exhaust manifold. The oil cooler is sealed to the cylinder block with a metal gasket and secured with seven bolts.

There are four ports on the underside of the cooler; an engine oil inlet and outlet and an engine coolant inlet and outlet. The engine oil cooler is an aluminium housing comprising louvered fins and plates. The plates allow a cross-flow of engine oil and engine coolant through the cooler but keep the two fluids separate. The plates are immersed in engine coolant from the engine variable coolant pump which provides cooling of the engine oil by the temperature differential between the engine oil and the engine coolant.

An anti-drain valve is located in the cylinder block and prevents the oil draining from the engine oil cooler when the engine is not running.

THERMOSTAT HOUSING

1. Main housing
2. Top cover
3. By-pass housing

1. Heater core return inlet
2. Exhaust Gas Recirculation (EGR) cooler supply outlet
3. Radiator upper hose outlet
4. Cylinder head outlet
5. Cylinder block outlet
6. Electric thermostat electrical connector
7. Engine Coolant Temperature (ECT) sensor
8. Thermal by-pass outlet to water inlet
9. Electric thermostat

The plastic thermostat housing is located on the side of the cylinder block below the intake manifold. The thermostat housing is secured to the cylinder block with four bolts and sealed with a rubber gasket. The thermostat is contained within the housing.

The plastic thermostat housing comprises a main housing, a welded top cover with the connection for the upper hose to the radiator and by-pass housing.

A by-pass valve is located in the by-pass housing attached to the main body of the thermostat. The by-pass valve has the function of limiting the by-pass flow when engine is cold and at low speed, below 1500rpm. The by-pass valve ensures that coolant flow is circulated through the heater core providing heated coolant to warm the vehicle interior.

The thermostat housing provides locations for the Engine Coolant Temperature (ECT) sensor and also has a connection for the electric thermostat which is located in the thermostat housing. The ECT sensor is used by the Engine Control Module (ECM) to determine the engine coolant temperature.

The function of the electric thermostat is to control the operating temperature of the engine. In economy (low load) conditions, the engine will operate at 98ºC (208.4ºF). At high load, the engine temperature is reduced for engine protection.

The electrical control is also used to control the thermostat opening to protect the cylinder block from over-temperature events.

The electric thermostat is not a serviceable component. Failure of the electric thermostat requires replacement of the thermostat housing.

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