DETROIT DIESEL 53
LUBRICATING OIL PUMP
The lubricating oil pump, assembled to the inside of the
between the inner and outer rotors on the inlet side of
lower engine front cover as illustrated in Fig. 1, is of the
the pump is then forced out under pressure through the
rotor type in which the inner rotor is driven by a gear
discharge port into a passage in the front cover which
pressed on the front end of the crankshaft. The outer
leads to the lubricating oil filter and cooler, an( is then
rotor is driven by the inner rotor. The bore in the pump
distributed throughout the engine.
body, in which the outer rotor revolves, is eccentric to
the crankshaft and inner rotor. Since the outer rotor
If a check of the lubrication system indicates improper
has nine cavities and the inner rotor has eight lobes, the
operation of the oil pump, remove and disassemble i; as
outer rotor revolves at eight-ninths crankshaft speed.
Only one lobe of the inner rotor is in full engagement
with the cavity of the outer rotor at any given time, so
Remove Oil Pump
the former can revolve inside the latter without
Drain the oil from the engine.
Remove the crankshaft pulley, fan pulley,
support bracket and any other accessories attached to
the front cover.
Remove the oil pan.
As the rotors revolve, a vacuum is formed on the inlet
Refer to Fig. 2 and remove the four bolts which
side of the pump and oil is drawn from the crankcase,
attach the oil pump inlet pipe and screen assembly to
through the oil pump inlet pipe and a passage in the
the main bearing cap and engine front cover or oil pump
front cover, to the inlet port and then into the rotor
inlet elbow. Slide the flange and the seal ring oil the
compartment of the pump. Oil drawn into the cavities
inlet pipe and remove the pipe and screen as an
assembly. Remove the oil pump inlet elbow (if used)
and gasket from the engine front cover.
Remove the lower engine front cover.
Fig. 1. - Typical Right-Hand rotation Lubricating Oil
Fig. 2. - Typical Oil Pump Inlet Pipe and Screen
1972 General Motors Corp.
SEC. 4.1 Page 1