Cylinder Block Components
CYLINDER BLOCK COMPONENTSThe main cylinder block components are:
^ Cylinder block
^ Connecting rods and pistons
^ Piston cooling jets
^ Generator
^ Gear housing
^ Thermostat housing
^ Crankshaft Position (CKP) sensor
^ Knock sensors
^ Coolant pump
^ Coolant inlet pipe
Cylinder Block
The cylinders and crankcase are contained in the cylinder block, which is of a cast aluminum construction. The cylinder sleeves are made of cast iron and cast in bores. The cylinder block is of a pen coolant mantle design, which allows coolant to flow freely around the upper section of the cylinders.
Connecting rods and Pistons
The connecting rods are 'L' profile forged with a trapezium shaped (a shape with 4 sides with 2 of its sides parallel) small end. The big end has a fracture split bearing cap, which gives a stable joint because the bearing cap and connecting rod are secured in the actual fracture surface. Aluminum bearings are used for both the lower and upper bearing half.
The pistons are cast from a light-alloy metal consisting of aluminum and silicon. The piston skirt is graphite coated at the front and rear to ensure low friction between the piston and cylinder, particularly during cold starting and during short periods of extreme load. The piston is 'weight optimized', which means, for example, that the piston pin is comparatively short and that the piston is missing material from the sides.
Each piston has 3 piston rings:
^ An upper compression ring of nitrated steel
^ A second ring of alloyed cast iron, which functions as both a compression ring and an oil scraper ring
^ A 3-part oil ring made of nitrated steel
Piston Cooling Jets
Jets located in the cylinder block spray oil on to the inside of the piston to provide piston and piston pin lubrication and cooling. The oil is distributed through the cylinder block, via the main oil gallery and channels bored in the block.
Generator
The generator is located at the rear of the intake side of the cylinder block. The generator is driven by the crankshaft gearwheel via the auxiliary unit shaft gearwheel and the auxiliary unit inner shaft gear wheel (see gear housing section for more information).
Gear Housing Components
The gear housing functions as an external cover for the following sub-sections:
^ Intermediate shaft
^ Camshaft drive outer shaft
^ Auxiliary unit inner shaft
Intermediate Shaft
The intermediate shaft is used to locate the camshaft drive shaft gear wheel in the cylinder block. The shaft is journaled with a double conical roller bearing. The auxiliary unit shaft drive gear wheel is in 2 pieces, with the narrow half being spring tensioned in the opposite direction to the wide half. This feature reduces noise because gear play is eliminated.
Only the wide half drives the auxiliary unit's gear wheel. The camshaft chain gear wheel is of the conventional design.
The shaft is sealed against the exhaust side (i.e. the rear side of the cylinder block) by a sealing washer. To remove or install the washer, the flywheel/flexplate must be removed.
Camshaft Drive Outer Shaft
The camshaft drive outer shaft is journaled at the front end of the shaft with a double row bearing in the gear housing.
Needle bearings are used at the rear end (pulley side) against the auxiliary unit shaft. The camshaft drive outer shaft gear wheel is in 2 pieces, a wide and a narrow half to reduce noise. The camshaft chain gear wheel is also located on the shaft and is used to drive the camshafts chain.
Auxiliary Unit Inner Shaft
The auxiliary unit inner shaft is journaled at the front end of the shaft (generator side) in the gear housing with a single row bearing. Needle bearings are used at the rear end (pulley side) against the camshaft drive shaft. There is a pulley at the rear end of the shaft that drives the Air Conditioning (AC) compressor and the power steering pump, via a polyvee belt. The shaft also drives the generator at the front end, via a sleeve connector.
Thermostat Housing
The thermostat housing is located towards the front of the intake side of the engine cylinder block. The housing contains a wax type thermostat and a coolant temperature sensor.
Coolant flows in at the coolant pump and passes through a number of channels before it collects and then flows out to the thermostat housing. If the thermostat housing is closed, the coolant passes via the by-pass channel directly to the coolant pump to then circulate through the cylinder block again.
Crankshaft Position Sensor
The Crankshaft Position (CKP) sensor is located at the rear of the intake side of the cylinder block. The sensor provides an input of engine crankshaft speed and position. The sensor works on the principle of the Hall effect and scans a trigger wheel (magnetic disc) on the flywheel.
Knock Sensors
The knock sensors are located at the front and rear intake side of the cylinder block. They are piezo-electric sensors that provide inputs to detect and locate detonation during combustion.
Coolant Pump
The coolant pump is installed on the RH side of the cylinder block rear face and is secured and sealed via 6 bolts and an 'O' ring. The coolant pump and power steering pump are both driven by a single pulley via a poly-vee belt. A keyed shaft at the front of the pulley drives the power steering pump, while a driver mechanism attached to the rear of the pulley drives the coolant pump.
Coolant Inlet Pipe
The coolant inlet pipe is located on the exhaust side of the engine. The coolant is routed from the coolant pump into 2 connections on the engine block via the coolant inlet pipe and leaves the engine block at the rear end, via the thermostat housing.