TM-9-2320-272-23-1

TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)

TECHNICAL MANUAL; FIELD MAINTENANCE MANUAL; VOLUME 1 OF 5

SEPTEMBER 2012

TM-9-2320-272-23-1 - Page 225 of 1313

ENGINE OIL SYSTEM OPERATION

The engine oil system provides lubricating oil for internal moving parts. Major components of the engine oil

system

are:

A. CRANKCASE BREATHER

- Vents hot engine oil fumes from engine and allows fresh air to enter.

B. ENGINE OIL COOLER

- Removes heat from engine oil as coolant circulates through internal tubes of

oil cooler.

C. OIL DIPSTICK

- Indicates engine oil level.

D. OIL FILTER

- Filters out foreign particles suspended in oil.

E. OIL FILLER CAP

- Located on rocker lever cover, cap covers engine oil fill opening.

F. OIL PRESSURE TRANSMITTER

- Sends an electrical signal that indicates engine oil pressure to gauge

on instrument panel.

G. OIL PAN DRAIN PLUG

- Plugs engine oil drain opening.

H. OIL PAN

- Reservoir for engine oil.

I. OIL SUPPLY LINE

- Carries oil from oil pan to oil pump.

J. OIL BYPASS RETURN LINE

- Returns oil from oil pump to oil pan.

K. OIL PUMP

- Provides mechanical pressurization of oil to circulate it through oil system.

TM 9-2320-272-23-1

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