Cylinder Head Components (Engine - Td4)

A thermal oil level sensor is fitted through the bottom plate of the sump and is fixed to the bottom plate by means of three studs and nuts. The oil drain plug with sealing washer is also fitted to the RH side of the bottom plate. The bottom plate is attached to the upper portion of the sump by means of 16 bolts, and a rubber-metal gasket seals the interface between the two components.

A port for the dipstick tube is included in the casting on the LH side of the sump.

An oil pick-up pipe with integral strainer locates in the centre of the sump oil pan to provide oil to the crankshaft driven oil pump.

Stiffener Plate The stiffener plate increases the rigidity of the lower engine block and is secured to the bottom of the cylinder block by 6 bolts.

Oil Pump The oil pump assembly is bolted to the bottom of the cylinder block and is located in front of the engine block stiffener plate. The pump is an internal rotor type with sintered rotors and is driven through a chain and sprocket system from the crankshaft.

A pressure relief valve is included at the outlet side of the oil pump to restrict oil pressure at high engine speeds by recirculating oil through the relief valve back around the pump to the inlet. The relief valve and spring is a plunger type; when oil pressure is great enough to lift the plunger, oil is allowed to escape past the plunger to relieve pressure and prevent further rise.

Oil is delivered to the pump from the pick-up pipe, and the outlet side of the oil pump delivers pressurised oil flow to the engine block main oil delivery gallery.

Crankshaft and Main Bearings The crankshaft is carried in 5 main bearings, number 4 main bearing having integral thrust washers for controlling end-float.

Cross-drillings in the crankshaft between adjoining main and big-end bearings are used to divert oil from the main bearings to lubricate the big-end bearings.

The crankshaft seals are made from PTFE. The front end of the crankshaft has a torsional vibration damper with integrated pulley attached for driving the ancillary components.

Each of the bearing caps are of cast iron construction and are attached to the cylinder block by two bolts. The bearing shells are of the split cylindrical type. The upper half shells are grooved to facilitate the supply of lubrication oil to the bearings and fit into a recess in the underside of the cylinder block. The lower half bearing shells are plain and fit into the bearing caps.

Cylinder Head Components

The cylinder head components are described below:

Cylinder Head The cylinder head is of aluminium gravity die casting construction. The cylinder head is bolted to the cylinder block by means of M12 cylinder head bolts arranged beneath each camshaft.

The cylinder head gasket is a multi-layer steel type and is available in three thicknesses. The choice of gasket thickness is dependent on the maximum piston protrusion.

The cylinder head has four ports machined at each cylinder location, two exhaust ports and two inlet ports. One of the inlet ports is helical and functions as a swirl port, the other is arranged laterally as a tangential port and functions as a charge port.

The cylinder head cooling system features combined longitudinal/transverse coolant flow. Coolant outlet is through a moulded plastic outlet elbow fixed to the cylinder head by three screws at the centre LH side of the cylinder head. The coolant thermostat is contained in a cast assembly at the inlet side and is bolted to the water pump which is driven from the ancillary drive belt. The coolant temperature sensor is screwed into an aperture at the rear LH side of the cylinder head. ENGINE MANAGEMENT SYSTEM - EDC, DESCRIPTION AND OPERATION, Description. COOLING SYSTEM - Td4, DESCRIPTION AND OPERATION, Description.