The engine lubrication system is of the force-feed type. The oil is supplied under full pressure to the
crankshaft, connecting rods, valve lifters, camshaft, and rear balance shaft bearing. A controlled
volume of oil is supplied to the valve rocker arms and push rods. All other moving parts are lubricated
by gravity flow or splash. The engine oil is stored in the lower crankcase (oil pan) which is filled
through a filler opening in the valve rocker arm cover. A removable oil level indicator, on the left side
of the engine block, is provided to check the oil level. The oil pump is located in the engine front
cover and is driven by the crankshaft. It is a gerotor-style pump which is a combination of a gear and
a rotor pump. It is connected by a passage in the cylinder block to an oil screen and pipe assembly.
The screen is submerged in the oil supply and has ample volume for all operating conditions. If the
screen becomes clogged, oil may be drawn into the system through the oil pressure relief valve in the
oil filter adapter.

Oil is drawn into the pump through the screen and pipe assembly, and a passage in the crankcase,
connecting to the passages in the engine front cover. Oil is discharged from the oil pump to the oil
filter adapter. The oil filter adapter consists of an oil filter bypass valve and a nipple for installation of
an oil filter. The spring-loaded oil pressure relief valve, located in the engine front cover, limits the oil
pressure. The oil filter bypass valve opens when the oil filter is restricted to approximately 68.95 kPa
(10 psi) of pressure difference between the oil filter inlet and discharge. The oil will then bypass 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. If the filter
element becomes restricted, not allowing engine oil to pass through, a spring-loaded bypass valve
opens. The main oil galleries run the full length of the engine block and cut into the valve lifter guide
holes to supply oil at full pressure to the valve lifters. Holes, drilled from the crankshaft bearings to the
main oil gallery, intersect the camshaft bearing bores to supply oil to the cam bearings.


Oil is transfered from the crankshaft bearings to the connecting rod bearings through holes drilled in
the crankshaft. Pistons, piston pins, and cylinder walls are lubricated by oil splash from the crankshaft
and connecting rods.

Each valve rocker arm and valve is supplied with oil through the tubular push rod. The oil comes from
the inside of the valve lifter passing around the metering valve and through a hole in the push rod
seat. Oil from the push rod passes through a hole in the push rod seat, and emerges on top of the
push rod seat boss.

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3800 V6 Engine Oiling System Operation