3.8L "3800" V6 - VIN [L]: Lubrication: Description
The engine lubrication system is of the force-feed type in which oil is supplied under full pressure to the crankshaft, connecting rods, camshaft bearings, valve lifters, and a controlled volume is supplied to the rocker arms and pushrods. All other moving parts are lubricated by gravity flow or splash.
The supply of oil is carried in the lower crankcase (oil pan) which is filled through a filter opening in the rocker arm cover. A removable oil level indicator (dip stick) rod on the left side of the crankcase is provided to check oil level.
The oil pump is located in the front cover and is driven by the crankshaft. It is a "gerotor" style pump which is a combination of gear and rotor pumps. It is connected by a passage in the cylinder crankcase to an oil screen housing and pipe assembly. The screen is submerged in the oil supply and has ample volume for all operating conditions. If the screen should become clogged for any reason, oil may be drawn into the system through the relief valve in the screen.
Oil is drawn into the pump through the screen and pipe assembly and a passage in the crankcase which connects to passages in the front cover. All oil is discharged from the pump to the oil pump filter adapter assembly which consists of an oil filter bypass valve and nipple for installation of an oil filter. The spring loaded oil pressure relief valve, located in the timing chain cover, limits the oil pressure. The filter by-pass valve opens when the filter has become restricted, to the extent that approximately 68.96 kPa (10 PSI) pressure difference exists between the filter inlet and discharge, to by-pass the oil filter and channel unfiltered oil directly to the main oil galleries of the engine.
A full flow oil filter is externally mounted to the oil filter adapter on the lower right front side of the engine. Normally all engine oil passes through the filter element, however, if the element becomes restricted, a spring loaded by-pass valve opens as mentioned above.
The main oil galleries run the full length of the crankcase and cut into the valve lifter guide holes to supply oil at full pressure to the lifters. Holes drilled from the crankshaft bearings to the main gallery intersect the cam bearing bores to supply oil to the cam bearings.
Holes drilled in the crankshaft carry oil from the crankshaft bearings to the connecting rod bearings. Pistons and cylinder walls are lubricated by oil thrown off the crankshaft and by connecting rod splash. Piston pins are lubricated by splash.
Each rocker arm and valve is supplied with oil through the tubular pushrod. This oil comes from the inside of the lifter, passing around the metering valve and through a hole in the lifter pushrod seat. Oil from the pushrod passes through a hole in the rocker arm pushrod seat, and emerges on top of the pushrod seat boss.
The crankshaft driven, gear-type oil pump provides pressurized lubrication to the main gallery. See Fig 1 . Oil pump and pressure regulator valve are located in front cover.