Description And Operation - Block Assembly
ENGINE BLOCK
The engine block is made of aluminum. It is a single block that includes the cylinders, coolant cavities and oil galleries.
On the exhaust side of the engine block there are mounting surfaces and related cavities for the following components:
- Oil Cooler
- Exhaust gas inlet for the low pressure Exhaust Gas Recirculation (EGR)
- Coolant inlet (from the coolant pump)
- EGR exhaust gas outlet from the crankcase (for the cylinder head)
On the inlet side of the engine block there are cavities for pre-separation of the oil vapors (1).
On the transmission side, you can see the surface with the readable engine identification along with a QR Code scannable code symbol (1) and the port (2) for the engine block heater (dealer installed accessory only available for cold climates).
On the timing side of the engine block are the bores for the two counter-rotating balance shafts, one on the intake side (1) and the other on the exhaust side (2).
The following information is shown in illustration on the surface of the exhaust side of the engine block:
- Cylinder tolerance classes
- Upper crankshaft main bearing tolerance classes
CRANKSHAFT
The engine drive components are designed to reduce overall rotational friction forces.
The crankshaft is made of steel and has 5 main journals, 4 crank pins and 4 counterweights. The main journals are numbered starting from the timing side (1st cylinder):
- Main journals
- 1st cylinder crank pin
- 2nd cylinder crank pin
- 3rd cylinder crank pin
- 4th cylinder crank pin
The nominal main journal diameter is: 50 mm. The nominal crank pin diameter is: 50 mm.
The crankshaft main journals rotate on main bearings located in the engine block. Aluminum alloy half-bearings are used (upper and lower) to reduce dragging friction. Along the outside diameter of the upper half-bearing, there is a hole (1) to allow engine oil to enter. Along the inside diameter there is the groove (2) that allows lubrication of the crankshaft main journal and provides oil to the crank pin lubrication cross-drillings. On both the half-bearings there is the centering "tang" (3).
The upper half-bearing has three tolerance classes identified by a number. The number is stamped on the outside surface. The lower half-bearing has 5 tolerance classes, also identified with a number stamped on the outside surface.
The crankshaft axial clearance is adjusted by two half-rings located at the 2nd main journal.
The crankshaft is supported from underneath by five main bearing caps. These are anchored to the engine block by two rows of bolts at the center (ten in total) and by two rows of bolts at the sides (ten in total).
An arrow stamped on the lower surface of each main bearing cap indicates the direction in which the bearing cap should be mounting on the engine block. The bearing cap must be mounted with the arrow pointing towards the timing side.
Data regarding the following bearing tolerance classes can be found on the front of the crankshaft (timing side):
- Lower crankshaft main bearing tolerance classes
- Connecting rod big end bearing tolerance classes
On the crankshaft counterweight next to the fifth main bearing, there is a crankshaft target wheel (1) with the Crankshaft Position (CKP) sensor facing it.
The crankshaft target wheel is fastened to the crankshaft counterweight with 3 screws. The crankshaft target wheel has 57 teeth around its circumference and one tooth that is the width of 3 teeth plus their related spacing.
PISTON AND CONNECTING ROD
The connecting rods are in forged steel. The big end (cap) is split so that it can be separated.
The connecting rod weight class (1) is stamped on the outside surface of the connecting rod bearing cap.
The connecting rod half-bearings (upper and lower) are classified according to 3 tolerance classes. The reference tolerance class is stamped on the outside surface of the half-bearings themselves.
The pistons are made of cast aluminum alloy with a graphite coating.
Indentations on the piston crown allow for intake valve clearance. There is a hollow area "dish" at the center of the piston crown that helps create the right amount of turbulence to mix the fuel and air.
The pistons have the following features:
- Piston crown hollow area (dish)
- Clearance for intake valves
- Arrow that indicates the timing side
- Part number
- Class indication
Combustion chamber pressure is captured by two compression rings, the first groove compression ring (1) and the second groove compression ring (2). The ring that scrapes the oil from the cylinder walls, the oil control ring (3), is in the third groove.
The piston pin is held in its place by two circlips (4).