Engine Lubrication: Description and Operation
Lubrication System-Low-PressureLow-Pressure Oil Flow
Part 1:
Part 2:
The lubrication system is pressure regulated, cooled and full flow filtered. In addition to providing engine lubrication, it supplies oil to the high-pressure oil system to control fuel delivery in the fuel injectors.
The following sequence describes lube oil flow through the major oil system components:
1. Oil pan (sump).
2. Oil pickup tube and screen.
3. The low pressure oil pump is a gerotor type contained in the front cover. The gerotor assembly consists of an outer and an inner gear. The inner gear is driven by the crankshaft. The pump inlet and outlet passages are through ports in the front cover.
^ Oil pressure regulator (bypass) controls lube oil pressure via a spring-loaded plunger relieving oil back to the inlet of the pump once operating pressure has exceeded 517 kPa (75 psi).
4. The oil cooler cover receives oil from the oil pump and cools it in the oil cooler, which is located underneath the oil cooler housing.
^ The cooler bypass valves open in the event that the oil cooler base and/or cooler becomes restricted.
5. The oil filter housing contains a paper type element. Unfiltered oil flows down and around the outside of the filter and then up through the center stand pipe.
^ The oil filter bypass allows oil to pass directly to the main oil gallery should the filter become restricted.
6. Turbocharger and drive gears.
^ Cooled and filtered oil supplied from the oil cooler base lubricates the turbocharger bearings and provides hydraulic pressure for the variable geometry turbocharger control valve. Oil drains from the turbocharger through a drain tube back to the high-pressure hydraulic pump cover.
7. Main galleries. Cooled and filtered oil supplied from the oil cooler base fills the main galleries to distribute oil to the following components via passages machined within the crankcase.
^ Hydraulic cam followers.
^ Camshaft main journals.
^ Crankshaft main journals.
^ Connecting rod bearings receive pressurized oil from the main bearings via drilled passages within the crankshaft.
^ Rocker arms receive lube oil from the hydraulic cam followers via the push rods. Oil drains back to the sump through holes located in the cylinder head.
^ Piston cooling tubes.
8. High-pressure hydraulic pump oil reservoir.
^ This reservoir (below oil cooler) has a constant supply of oil for the pressure hydraulic oil pump. It has an approximate capacity of 0.9 liter (0.95 quart).
Lubrication System-High Pressure
The high pressure oil system is composed of two subsystems:
^ Injection Control Pressure (ICP) system
^ Fuel injector assembly
The hydraulic force necessary to inject fuel into the combustion chamber is provided by the ICP system. The fuel injectors on the engine are hydraulically actuated and electronically controlled.
The ICP system is composed of the following components:
^ Oil reservoir
^ Oil pump assembly (high pressure)
^ Oil pump cover
^ High-pressure tubes
^ High-pressure rail assemblies
^ Injection Control Pressure (ICP) sensor
^ Injection Pressure Regulator (IPR) valve
^ Check valves
The high-pressure oil pump receives engine lube oil from a reservoir cast into the vee of the crankcase. This reservoir makes available a constant supply of engine oil from the pump. This reservoir is constantly refilled by the low-pressure lube oil system with filtered oil from a passage in the oil cooler housing.
The high-pressure oil pump is mounted at the rear of the crankcase and is driven by the camshaft gear. Oil is drawn from the oil reservoir through a 200-micron screen and into a passage to the pump inlet port. High-pressure oil from the pump is distributed to the injectors through a series of tubes and manifolds.
The high-pressure discharge tube is mounted to the pump and serves to connect the oil flow from the high-pressure oil pump to the rear engine tube assembly. This tube assembly divides oil flow into two tubes or branches, one for each side of the engine. Rigid tubes in each branch direct oil up into the high-pressure oil rail of each cylinder head. Oil from the rails enters the injectors through O-ring sealed ports at the top of each injector. When the injector opening coil is energized, high-pressure oil is used to push fuel into the combustion chamber. After injection is complete, the oil inside the injector is vented through the top portion of the injector and allowed to drain back to the oil sump.