Engine Lubrication: Description and Operation
LUBRICATIONDESCRIPTION
NOTE: Refer to and for circuit illustrations.
A gear driven gerotor type oil pump is mounted behind the front gear cover in the lower right portion on the engine.
OPERATION
A gerotor style oil pump draws oil from the crankcase through the suction tube and delivers it through the block where it enters the oil cooler cover and pressure regulator valve. When oil pressure exceeds 517 kPa (75 PSI), the valve opens exposing the dump port, which routes excess oil back to the oil pump.
At the same time, oil is directed to a cast in passage in the oil cooler cover, leading to the oil cooler element. As the oil travels through the element plates, it is cooled by engine coolant traveling past the outside of the plates. It is then routed to the oil filter head and through a full flow oil filter. If a plugged filter is encountered, the filter by-pass valve opens, allowing unfiltered oil to lubricate the engine. This condition can be avoided by frequent oil and filter changes, per the maintenance schedules found in the owners manual. The by-pass valve is calibrated to open when it sees a pressure drop of more than 345 kPa (50 psi) across the oil filter.
The oil filter head then divides the oil between the engine and the turbocharger. The turbocharger receives filtered, cooled and pressurized oil through a supply line from the filter head. The oil lubricates the turbocharger and returns to the pan by way of a drain tube connecting the bottom of the turbocharger to a pressed in tube in the cylinder block.
CAUTION: Two different styles of J-jet piston cooling nozzles and nozzle mounting fasteners are used, depending on engine build date. The two designs are NOT interchangeable. One design uses an all metal piston cooling nozzle (1) with a fluted mounting capscrew (3). The second design uses a plastic nozzle/body/locating arm (5), and a metal nozzle tip (4). The second design nozzle must be used with a banjo bolt (6). When replacing piston cooling nozzles, it is important to replace the cooling nozzle mounting fastener with the same type that was removed. Do not intermix both designs in the same engine. Severe engine damage can result if the two designs are intermixed.
Oil is then carried across the block to an angle drilling which intersects the main oil rifle (3). The main oil rifle (3) runs the length of the block and delivers oil to the crankshaft main journals and valve train. Oil travels to the crankshaft through a series of transfer drillings (one for each main bearing) and lubricates a groove in the main bearing upper shell. From there another drilling feeds the camshaft main journals. J-jet piston cooling nozzles (1,4) are supplied by a separate oil rifle. Plugs are used in place of saddle jets when J-jets are used. Crankshaft internal cross-drillings supply oil to the connecting rod journals.
Another series of transfer drillings intersecting the main oil rifle supply (14) the valve train components. Oil travels up the drilling, through a hole in the head gasket, and through a drilling in the cylinder head (one per cylinder), where it enters the rocker arm pedestal (3) and is divided between the intake and exhaust rocker arm (1). Oil travels up and around the rocker arm mounting bolt, and lubricates the rocker shaft (2) by cross drillings that intersect the mounting bolt hole. Grooves at both ends of the rocker shaft supply oil through the rocker arm where the oil travels to the push rod and socket balls and.