1 ENGINE SYSTEMS 39
diverted to the oil cooler plate stack or by-passed into
the oil cooler/filter module.
An oil temperature control valve, in the oil cooler/filter
header, senses inlet oil temperature. During engine
start-up, when the oil is cold, the oil temperature
control valve allows unfiltered oil to bypass the oil
cooler plate stack. W hen the unfiltered oil reaches
engine operating temperature, the oil temperature
control valve routes unfiltere d oil to the oil cooler. Oil
flows through both the oil cooler core and bypass
gallery when the valve is partially open.
Unfiltered oil at full flow moves through plates in the
oil cooler. Engine coolant fl ows through the plates to
cool the surrounding oil.
The cooled, unfiltered oil leaving the oil cooler stack
mixes with the uncooled, unfiltered oil (that bypassed
theoilcooler). Theoilmixtureflows through the oil
filter (from element outside to element inside). The
oil filter bypass valve in the header ensures full flow
of oil to the engine should the filter element become
plugged. Oil bypass occurs within the module when
differential filte r pressure reaches 345 kPa (50 psi).
Cooled, filtered oil flows to and past the oil pressure
regulator relief valve, in the oil cooler module. The oil
pressure regulator valve maintains correct operating
oil pressure.
The pressure regulator valve opens at 379 kPa
(55 psi) and dumps excess oil into the crankcase.
The filtered oil continues to th e ma in oil gallery for
distribution throughout the engine.
Connecting rod bearings are fed through drilled
passages in the crankshaft from main journals to rod
journals, that receive pressurized oil from the main
bearings.
Camshaft journ a ls are fed th ro ug h passages drille d
vertically in the main b earing webs. P ressurized oil
from the main gallery, through piston cooling tubes,
lubricates and cools the pistons.
Valve rocker arms are lubricated through an annulus
on the outside of the rear camshaft bushing. The oil
passes up and through the vertical gallery in the rear
of the crankcase, through a passage in the cylinder
head. Oil continues through rocker arm s haft pedestal
and into the rocker arm shaft. Oil continues flowing
through drillings in the rocker arm shaft to the rocker
arms. The oil then drains to the oil pan sump through
push rod holes.
Filtered oil from the main gallery flows up throug h a
passage in the front of the crankcase and front cover
into the oil reservoir for the high-pressure oil pump.
The turbocharger receives filtered oil through an
external tube connected to the oil cooler header.
Oil drains back to the oil pan sump through a tube
connected to the crankcase.
The air compressor (if equipped) receives filtered oil
from the main oil gallery through an external tube
connected to the left side of the crankcase. Oil drains
to the front cover and back to the oil pan.
The front gear train is splash lubricated with oil
draining from the high-pressure reservoir and the air
compressor (if equipped).
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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