Engine - Td4 (Description): Description and operation

Description

General

The Td4 diesel engine is a 2.0 litre, 4 cylinder, in-line direct injection unit having four valves per cylinder operated by twin overhead camshafts. The engine emissions comply with EU-3 (European Commission Directive) legislative requirements and employs a catalytic converter, positive crankcase ventilation and exhaust gas recirculation to limit the emission of pollutants. The unit is water cooled and turbo-charged and is controlled by an electronic engine management system. Fuel injection features common rail technology.

The engine is controlled by a DDE 4.0 engine management system. ENGINE MANAGEMENT SYSTEM - EDC, DESCRIPTION AND OPERATION, Description.

The cylinder block is of cast iron construction with a cast aluminium stiffening plate bolted to the bottom to improve lower structure rigidity. The cylinder head is cast aluminium with a moulded plastic camshaft cover. The engine sump is a two-piece cast aluminium assembly. A moulded plastic acoustic cover is fitted over the upper engine to reduce engine generated noise.

The engine utilises the following features: l Direct fuel injection utilising a common rail and high pressure injectors controlled by an engine management system for precise fuel delivery under all prevailing operating conditions. A high pressure intermediary fuel pump is chain driven from the crankshaft to supply fuel to the common rail l 4 valves per cylinder with centrally arranged injection nozzle l Turbocharging which delivers compressed air via an intercooler to the combustion chambers for improved power output l Exhaust gas recirculation to improve emissions through the reduction of NO2 l Oil cooler to keep engine lubrication oil cool under heavy loads and high ambient temperatures

Cylinder Block Components

The cylinder block components are described below:

Cylinder Block The cylinders and crankcase are contained in a single grey cast iron construction with hollow beam structure. The cylinders are direct bored. Lubrication oil is supplied via lubrication jets for piston and gudgeon pin lubrication and cooling.

Lubrication oil is distributed throughout the block via the main oil gallery to critical moving parts through channels bored in the block which divert oil to the main bearings, and to the big-end bearings via holes machined into the crankshaft.

An oil cooler is fitted to the side of the oil filter assembly with ports in the oil cooler mating with ports in the oil filter assembly, to facilitate coolant and oil flow from the cylinder block. An oil pressure switch is included in a tapping in the oil filter assembly which is used to determine whether sufficient oil pressure is available to provide engine lubrication and cooling.

A tapping at the front RH side of the cylinder block connects a pipe to the turbocharger by means of a banjo connection. Oil under pressure from the oil pump provides lubrication for the turbocharger bearings.

Cylinder cooling is achieved by coolant circulating through chambers in the engine block casting. Note that the water jacket does not have core plugs.

Two hollow metal dowels are used to locate the cylinder block to the cylinder head, one on each side at the front of the unit. Two additional hollow metal dowels are used to locate the timing cover to the cylinder block.

Connecting Rods The connecting rods are machined, H-sectioned steel forgings. The big-end bearing shells are plain split halves. The upper half bearing shell fitted to the connecting rod is treated using the sputtering process (cathodic surface coating process) to improve its resistance to wear.

The small-end of the connecting rod has a bushed solid eye which is free to move on the gudgeon pin. The small-end bushing is a hand-push transition fit.