3-38. LUBRICATING OIL PUMP - MAINTENANCE INSTRUCTIONS.
The gear-type lubricating oil pump is mounted on the number one and two main b aring caps at
the front of the engine and is driven by a gear mounted on the crankshaft.
An oil outlet opening is provided on each side of the pump housing to accommodate connections
to the oil cooler and filter mounted on either side of the right front side of the cylinder block.
The greatest amount of wear in the oil pump is on the internal drive and driven gears. This wear
can be kept to a minimum by keeping the lubricating oil clean and acid-free. Do not allow dirt and sludge to
accumulate in the lubricating system as wear may occur in a short period of time. Proper servicing of the oil
filters will increase the life of the gears.
Oil is drawn by suction from the oil pan through the intake screen and pipe into the oil pump where
it is pressurized. It passes from the pump through the block and out to the full-flow oil filters, through the oil
cooler and into the oil galleries in the cylinder lock.
An oil pump pressure relief valve is located between the oil pump outlet and the cylinder block
vertical oil gallery leading to the oil filter and oil cooler. This valve opens at approximately 120 psi (827.4 kPa)
and returns excess oil to the oil pan.
Stabilized lubricating oil pressure is maintained in the engine at all speeds, regardless of the oil
temperature, by means of a regulator valve mounted beneath the cylinder block at the lower end of the vertical
oil gallery on the side opposite the oil cooler. This valve opens at approximately 50 psi (344.8 kPa) and returns
excess oil directly into the oil pump.