DETROIT DIESEL 53
IN - LINE ENGINES
The lubricating oil pump, assembled to the inside of the lower engine front cover as illustrated in Fig. 1, is of the rotor
type in which the inner rotor is driven by a gear pressed on the front end of the crankshaft. The outer rotor is driven by
the inner rotor. The bore in the pump body, in which the outer rotor revolves, is eccentric to the crankshaft and inner
rotor. Since the outer rotor has nine cavities and the inner rotor has eight lobes, the 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 the former can revolve inside the latter without interference.
By rotating the pump 180 °, it can be used for either a right-hand or left-hand rotation engine.
As the rotors revolve, a vacuum is formed on the inlet side of the pump and oil is drawn from the crankcase, through the
oil pump inlet pipe and a passage in the front cover, to the inlet port and then into the rotor compartment of the pump.
Oil drawn into the cavities between the inner and outer rotors on the inlet side of the pump is then forced out under
pressure through the discharge port into a passage in the front cover, which leads to the lubricating oil filter and cooler,
and is then distributed throughout the engine. If a check of the lubrication system indicates improper operation of the oil
pump, remove and disassemble it as outlined below.
Remove Oil Pump
Drain the oil from the engine.
2. Remove the crankshaft pulley, fan pulley, support bracket and any other accessories attached to the front cover.
3. Remove the oil pan.
4. Refer to Fig. 2 and remove the four bolts which attach the oil pump inlet pipe and screen assembly to the main
bearing cap and engine front cover or oil pump inlet elbow. Slide the flange and the seal ring on the 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
5. Remove the lower engine front cover.
Fig. 2 - Typical Oil Pump Inlet Pipe and
Fig. 1 - Typical Right - Hand Rotation Lubricating
Oil Pump Mounting
July , 1972
Sec 4.1 Page 1