THEORY OF OPERATION
Transmission Oil Cooler
ENGINE COMPONENTS (Continued)
Oil Coolers, Transmission and Engine:
External oil coolers accomplish transmission and
engine oil cooling. The oil coolers are located on the
sides of the engine above the cylinders. Air is drawn
through the oil coolers by the cooling fans. A
thermostatic control valve in each oil cooler controls
the temperature of the oil from the cooler by
permitting cold oil to bypass the coolers. This valve
also permits oil to bypass the cooler in the event that
the cooler becomes clogged.
The oil pan acts as a reservoir for the oil, and
is the base for the cylinder block, thereby
forming a strong engine structure.
It is a one-piece aluminum alloy casting
divided into an oil pump pressure
compartment, an oil reserve compartment, and
a sump compartment. Cored passages from
each of the compartments terminate at a
central outlet and permits draining. A
separate passage permits draining the oil
coolers and oil filter compartment directly
without permitting any sludge to enter the oil pan. The oil pan is designed to maintain a
constant oil level, above the oil pump pickup tube, regardless of the angle at which the
engine/vehicle is operated.
The oil pump provides pressure to circulate oil to engine parts
The oil pump consists of four sections combined in a single
unit. The main section (pressure) draws oil from the oil pump
pressure compartment in the oil pan. This oil pan
compartment is fed by the scavenge section of the pump
which picks up oil from the sump compartment at the front
end of the oil pan and by oil which drains into the pressure
compartment from the cover of the pressure pump compartment and the reserve compartment.
The dual inlet make-up section picks up oil from opposite corners of the reserve compartment.
The dual inlet feature assures that the inlet to the main section is supplied regardless of engine
tilt. The leveling pump section returns any excess oil to the reserve compartment. The make-
up section and the leveling pump section work together to maintain a constant level in the
main pressure compartment.
WP 0004 00-25