Cylinder head parts (Discovery 3)

Item name	Spare part catalog number	Description
1	-	Camshaft Bearing Cap
2	-	Valve lifter (without gasket)
3	-	Sleeve
4	-	Valve spring cap
5	-	Valve spring
6	-	Valve stem seal
7	-	Valve
8	-	Intake camshaft
9	-	Exhaust camshaft

Cylinder heads

The cylinder heads of each row are not interchangeable. The cylinder head is fastened to the cylinder block with deep-set bolts to reduce deformation. Two hollow pins ensure the alignment of each cylinder head with the cylinder block.

Spark plugs with a diameter of 14 mm, one plug per cylinder, are located in recesses on the axis of each cylinder head.

The engine mounting lugs are bolted to the cylinder heads - two at the rear (one for each head) and one in the front.

Camshaft covers

The camshaft covers are made of thermoplastic. The A-bank camshaft cover has a part-load breather hole. The B-bank camshaft cover has a full-load breather hole and an oil filler neck. Identical oil separators are located below the breather hole in each cover. For more information, refer to Electronic Engine Controls (303-14B Electronic Engine Controls - 4.4L)


Between the camshaft covers and the cylinder heads, silicone rubber gaskets are located in a recess. Together with the spacer bushings and seals on the camshaft cover fasteners, they isolate the covers from direct contact with the cylinder heads, thus reducing noise levels.

Cylinder head gasket

The multi-layer steel cylinder head gasket has different coolant passages for each cylinder, which ensures uniform fluid flow.

Camshafts

The camshafts are made of chilled cast iron. Five aluminum alloy caps hold each camshaft. The caps are numbered on the top side - 0 through 4 for the intake camshaft and 5 through 9 for the exhaust camshaft.

Sensor ring

Item name	Spare part catalog number	Description
1	-	Intake camshaft
2	-	Sensor ring

The rings for each camshaft position sensor are located at the rear of both camshafts. A flat machined surface near the front of both camshafts allows them to be locked when performing valve timing adjustments.

Camshaft Position Sensor

The camshaft position sensors are located in each cylinder head at the rear of the intake camshaft. The sensor is an electromagnetic sensor that generates a signal to the ECM containing information about the position of the camshaft. For more information, refer to Electronic Engine Controls (303-14B Electronic Engine Controls - 4.4L)

Inlet and outlet valves

Each cylinder head contains two overhead camshafts, actuating four valves per cylinder via solid, non-adjustable aluminum alloy tappets.

Lightweight valve mechanism ensures low fuel consumption and noise level. Valve head diameter: 31 mm on the exhaust and 35 mm on the intake. All valves have a stem diameter of 5 mm; the seat and guide bushings are made of metal powders by sintering. Between the bushings, valve plates and spring seats are located single valve springs on both the intake and exhaust valves. Valve stem seals are built into the spring seats.

NOTE: Due to some differences in length, valves are not interchangeable between different makes of vehicle. (Land Rover, Jaguar and Aston Martin).

Fuel injectors

The fuel rails contain eight 12-nozzle, top-fed fuel injectors. The injector is released by a solenoid valve controlled by the ECM. Two O-rings seal the contact between the fuel rail and each injector. The injectors deliver fuel to the rear of the intake valves. For more information, refer to Electronic Engine Controls (303-14B Electronic Engine Controls - 4.4L)