TRUCK SERVICE MANUAL
ENGINE
Lubricating oil is drawn from the pan, through a suction
Filtered and cooled lubricating oil re-enters the block
tube, by the lubricating oil pump, Fig. 5-13, then
from the cooler support and is transferred internally back
transferred from the suction cavity by the pump gears
across the front of the block through a drilled oil transfer
into the pressure cavity.
passage to the head of the main rifle drilling. Accessory
Lubricating oil passes from the pump into the block, then
drive lubrication is supplied from the transfer passage
across the front of the block by means of an internal oil
out the front of the block and into the gear cover on the
passage and enters the cooler support. Oil is routed out
exhaust side of the engine, then across the front of the
of the cooler support and into the cooler housing,
engine through a tube in the gear cover. The flow path
passing through the cooler housing. (The oil cooler is a
then splits, part being routed to the accessory drive
counterflow tube-and-shell type heat exchanger, with oil
bushing in the gear cover and the rest being routed to
passing from front to rear through the shell and coolant
the air compressor.
water passing from rear to front through the tubes.) Oil
Piston-cooling is supplied from the transfer passage
exits the cooler housing and passes into the cooler
leading to the head of the main rifle drilling. An
cover, then enters the "rifle drilling" at the bottom rear of
intersecting drilling allows flow to the piston-cooling rifle
the cooler housing and flows forward into the filter head.
which extends from the front to the rear of the block on
Lubricating oil flowing into the filter shell from the filter
the exhaust side of the engine. Six piston-cooling
head enters outside the filter element and passes
nozzles inserted from the outside of the block direct a
through the element from outside to inside. Filtered
spray of lubricating oil from the piston-cooling rifle to the
lubricating oil then re-enters the filter head and flows
bottom of each piston.
through rifle drilling in the bottom of the cooler housing,
Lubricating oil entering the main rifle is routed by means
then flows forward out of the cooler housing and into the
of drilled passages and pipes to the main bearings, rod
cooler
support
where
the
flow
divides.
bearings, piston pin bushings, camshaft bushings, cam
follower shafts and levers, rocker box shafts and rocker
arms, etc. then returns to the oil pan.
Cooling System
Water is circulated by a centrifugal water pump mounted
either in or on the front of the engine belt driven from the
accessory drive or crankshaft.
Water circulates around wet-type cylinder liners, through
the cylinder heads and around injector sleeves. Injector
sleeves, in which injectors are mounted, are designed for
fast dissipation of heat. The engine has a thermostat to
control engine operating temperature. Engine coolant is
cooled by a radiator and fan or a heat exchanger.
The Fleetguard D C A Water Filter is standard on
Cummins Engines. The filter by-passes a small amount
of coolant from the system via a filtering and treating
element which must be replaced periodically.
In some cases the turbocharger is used for the engine to
Air System
retain efficiency (balanced fuel to air ratio) at altitude
The diesel engine requires hundreds of gallons of air for
above sea level.
every gallon of fuel that burns. For the engine to operate
The turbocharger consists of a turbine wheel and. a
efficiently, it must breathe freely, intake and exhaust
centrifugal blower, or compressor wheel, separately
systems must not be restricted.
encased but mounted on and rotating with a common
The intake air should always be routed through an air
shaft.
cleaner. The cleaner may be mounted on engine or
The power to drive turbine wheel - which in turn drives
equipment and may. be either oil bath, paper element of
the compressor - is obtained from energy of engine
composite type depending upon engine application. Air
exhaust gases. Rotating speed of the turbine changes
is routed from air cleaner directly to intake air manifold or
as the energy level of gas changes; therefore, the engine
turbocharger.
is supplied with enough air to burn fuel for its load
Turbocharger
requirements.
The turbocharger forces additional air into combustion
The turbocharger is lubricated and cooled by engine
chambers so engine can burn more fuel and develop
lubricating oil.
more horsepower than if it were naturally aspirated.
315
