Land Rover Discovery Owners & Service Manuals

Land Rover Discovery: Glow Plugs

Glow Plugs

  1. Glow plug (4 off)
  2. Glow plug harness

The glow plug system has a glow plug installed in the inlet side of each cylinder. The glow plugs heat the combustion chambers before and during cranking, to aid cold starting, and after the engine starts to reduce emissions and engine noise when idling with a cold engine. The glow plugs are connected by a common harness which is connected into the main engine harness. The glow plugs are connected directly to a glow plug control module which is controlled by glow plug software contained within the Engine Control Module (ECM). The glow plug control module is located in the left wheel arch.

Glow Plug Control Module

Glow Plug Control Module

Each glow plug is a tubular heating element which contains a spiral filament 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 current to the heater coil to safeguard against overheating.

In the event of glow plug failure, the engine may be difficult to start and excessive smoke emissions may be observed after starting.

EXHAUST MANIFOLD

EXHAUST MANIFOLD

  1. Screw (4 off)
  2. Gasket assembly
  3. Exhaust manifold
  4. Heat shield - turbocharger
  5. Heat shield - upper
  6. Heat shield - upper
  7. Heat shield - lower
  8. Bolt (8 off)
  9. Heat shield - upper
  10. Output to Exhaust Gas Recirculation (EGR) valve

The exhaust manifold is cast from an iron alloy with a high nickel content giving excellent heat and corrosion resistance properties. The manifold is sealed to the cylinder head by means of a steel gasket and heat shield assembly. Spacers on the securing bolts allow the manifold to expand and retract with changes of temperature while maintaining the clamping loads.

A threaded boss is located under the turbocharger flange which provides the connection of an exhaust gas temperature sensor.

The exhaust manifold has a connection for the Exhaust Gas Recirculation (EGR) transfer pipe to the High Pressure (HP) EGR valve.

The exhaust manifold has a connection for the Exhaust Gas Recirculation (EGR) transfer pipe to the High Pressure (HP) EGR valve.

The engine is fitted with a Variable Geometry Turbocharger (VGT) which is located on the top of the exhaust manifold on a three hole flange mounting and sealed with a steel gasket.

EXHAUST GAS RECIRCULATION (EGR)

EXHAUST GAS RECIRCULATION (EGR)

  1. EGR valve motor
  2. EGR outlet to intake manifold
  3. EGR tube from exhaust manifold
  4. Air inlet from air filter
  5. Pierce point for engine breather hose
  6. Turbocharger attachment
  7. Engine coolant connection
  8. Diesel Particulate Filter (DPF) connection
  9. EGR cooler
  10. EGR tube assembly

There are two main external Exhaust Gas Recirculation (EGR) systems that are used on the engine - High Pressure (HP) EGR and Low Pressure (LP) EGR.

EGR is used to cool the combustion in the cylinders by introducing exhaust gases without oxygen (exhaust gas). This in turn allows the use of smaller fuel injections, improving emissions and fuel economy.

HP EGR

The HP EGR valve is located on the left side of the engine and secured to the cylinder head via a mounting bracket. Exhaust gases are routed to the HP EGR valve from the exhaust manifold. The EGR valve is cooled using engine coolant in the passenger compartment heater core circuit; this is to protect the electrical components from over-heating. The HP EGR valve controls the amount of EGR exhaust gas flow depending on the Engine Control Module (ECM) map. The exhaust gases are passed directly into the intake manifold via a simple EGR pipe on EU5/6 market vehicles. The design of the EGR pipe attachment to the inlet manifold helps mix the exhaust gasses with the main fresh air intake and also insulates the plastic intake manifold from the hot EGR pipe.

LP EGR

The LP system takes exhaust gases from the exit of the Diesel Particulate Filter (DPF) or the SCR on EU6 market vehicles, and mixes it with the fresh air intake into the turbocharger.

An additional pipe is welded to the DPF (or SCR on EU6 market vehicles) outlet pipe, which routes the exhaust gases from the outlet pipe to the Low Pressure (LP) Exhaust Gas Recirculation (EGR) cooler. The LP EGR cooler has no bypass mode, cools all exhaust gas passing through it. There is a simple mesh filter fitted before the gases reach the outlet of the cooler that prevents larger particles of soot etc from entering the turbocharger system.

The mesh filter is non-serviceable.

The cooled gases are then directed through the LP EGR valve via a butterfly valve. The valve consists of a tube between the fresh air duct and the turbocharger, with the butterfly valve covering the EGR inlet, in the center bottom of the EGR valve. The butterfly valve opens into the fresh air stream, promoting thorough mixing before the gas enters the turbocharger, and also provides 'suction' to drive the LP EGR gas through the system.

For additional information, refer to: Engine Emission Control (303-08B Engine Emission Control - INGENIUM I4 2.0L Diesel, Description and Operation).

INTAKE MANIFOLD

INTAKE MANIFOLD

  1. Electric throttle
  2. Manifold Absolute Pressure and Temperature (MAPT) sensor
  3. Seal (8 off)
  4. Bolt (9 off)
  5. EGR inlet

The inlet manifold is a plastic injection moulded assembly made from two shells vibration-welded together. The intake manifold is mounted directly to the cylinder head with nine bolts and sealed with eight flexible seals.

The main function of the intake manifold is to evenly distribute intake air from the air filter and intake distribution system into the combustion chamber of each cylinder.

A Manifold Absolute Pressure and Temperature (MAPT) sensor is located on the top of the intake manifold and secured a screws. The MAPT sensor is used by the Engine Control Module (ECM) to calculate air density and temperature and determine the engine's air mass flow rate.

The electric throttle is attached to the intake manifold with four screws. A gasket seals the joint between the electric throttle and the intake manifold.

NOISE, VIBRATION AND HARSHNESS (NVH) PADS

Noise, Vibration and Harshness (NVH) pads are fitted on the Ingenium I4 2.0L Diesel engine in order to reduce NVH experienced by the driver or passenger(s). The pads are made of either a PUR foam or a multi-layer mixed fibre and resin laminate composite depending on application.

The NVH package consists of a pad for each side of the engine cylinder block, an engine cover located on the top of the engine and an oil pan cover.

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