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.
| 1 - Oil Cooler |
| 2 - Exhaust Gas Inlet For The Low Pressure Exhaust Gas Recirculation (EGR) |
| 3 - Coolant Inlet (from the coolant pump) |
| 4 - EGR Exhaust Gas Outlet From The Crankcase (for the cylinder head) |
On the left side of the engine block there are machined mounting surfaces and related cavities for the oil cooler, EGR low pressure gas inlet, coolant inlet and the EGR gas outlet.
| 1 - Oil Vapor Pre-Separation Cavities |
On the right side of the engine block there are cavities for pre-separation of the oil vapors.
| 1 - QR Code |
| 2 - Engine Block Heater Port |
On the transmission side the block is machined to mate to the transmission and a machined pad for the readable engine identification along with a QR Code scannable code symbol. The port for the engine block heater (dealer installed accessory only available for cold climates) is located near the rear of the block.
| 1 - Intake Side Balance Shaft |
| 2 - Exhaust Side Balance Shaft |
On the timing side of the engine block are the bores for the two counter-rotating balance shafts, one on the intake side and the other on the exhaust side.
| 1 - Cylinder Tolerance Classes |
| 2 - Upper Crankshaft Main Bearing Tolerance Classes |
The information for the cylinder tolerance class and upper main bearing tolerance class is located on a machined surface located at the lower rear right side of the engine block.
CRANKSHAFT
The engine drive components are designed to reduce overall rotational friction forces.
| 1 - Main Bearing Journal |
| 2 - Cylinder 1 Crank Pin |
| 3 - Cylinder 2 Crank Pin |
| 4 - Cylinder 3 Crank Pin |
| 5 - Cylinder 4 Crank Pin |
The crankshaft is made of steel and has five main journal to support the crankshaft in the block, four crank pins and four counterweights. The main journals are numbered starting from the timing side (1st cylinder). The crankshaft is cross-drilled to allow pressurized engine oil from the main bearings to reach the connecting rod bearings.
| 1 - Lubrication hole |
| 2 - Groove |
| 3 - Centering Tangs |
The crankshaft main journals rotate on select fit main bearings located in the engine block. Aluminum alloy half-bearings are used (upper and lower) to reduce dragging friction. The upper half main bearing has a lubrication hole and a groove to allow engine oil to enter and lubricate of the crankshaft main journal and provide oil to the crank pin lubrication cross-drillings. On both the half-bearings there are centering tangs to properly locate the bearings.
The upper half-bearing has three tolerance classes identified by a number stamped on the outside of the lower rear right side of the engine block. The lower half-bearing has 5 tolerance classes, also identified with a number stamped on the front of the crankshaft.
The crankshaft axial clearance (thrust) is adjusted by two half-rings located at the 2nd main bearing journal.
| 1 - Arrow |
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.
| 1 - Lower Crankshaft Main Bearing Tolerance Classes |
| 2 - Connecting Rod Bearing Tolerance Classes |
Data regarding the lower crankshaft main bearing and connecting rod bearing tolerance classes can be found stamped into the front of the crankshaft (timing side).
| 1 - Crankshaft Target Wheel |
The crankshaft target wheel is fastened to the crankshaft counterweight next to the fifth main bearing with 3 screws. The crankshaft target wheel toggles the Crankshaft Position (CKP) sensor signal. The crankshaft target wheel has 57 equal teeth around its circumference and one tooth that is the width of 3 teeth plus their related spacing. The larger tooth serves to provide an indexing point for actual crankshaft position to the CKP.
PISTON AND CONNECTING ROD
The connecting rods are forged steel. The big end (cap) is split so that it can be separated. 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 small end of the connecting rod has a bushing for the full floating wrist pin that attaches the piston to the connecting rod.
| 1 - Connecting Rod Weight Class |
The connecting rod weight class is stamped on the outside surface of the connecting rod bearing cap.
| 1 - Piston crown hollow area (dish) |
| 2 - Clearance for intake valves |
| 3 - Arrow that indicates the timing side |
| 4 - Part number |
| 5 - Class indication |
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 are attached to the connecting rods via a full floating wrist pin that is held into place by two circlips in the piston pin bore.
| 1 - First Groove Compression Ring |
| 2 - Second Groove Compression Ring |
| 3 - Oil Control Ring |
Combustion chamber pressure is captured by the first groove compression ring and the second groove compression ring. The ring that scrapes the oil from the cylinder walls, the oil control ring, is in the third groove.