Navistar MaxxForce 15, Service Manual

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10 ENGINE SYSTEMS
The crankshaft has seven main bearings with fore
and aft thrust controlled at the forth bearing. One
connecting rod is attached at each crankshaft journal.
The piston pin moves freely inside the connecting rod
and piston. Piston pin retaining rings secure the piston
pin in the piston. The rear oil seal carrier is part of the
flywheel housing, and the front oil seal carrier is part
of the front cover.
An oil pump is mounted within the oil pan to the
bottom of the crankcase behind the front cover and is
driven by the crankshaft. Pressurized oil is supplied
to internal engine components, air compressor, power
steering pump and turbochargers. All MaxxForce®
15 engines use an engine oil cooler and a spin-on
can style engine oil filter element.
Fuel is drawn from the fuel tank through the
frame-mounted fuel/water filter separator.
A hand
operated primer pump is located either on top of
or next to the frame-mounted fuel/water separator.
The fuel is then routed into the fuel pump and to the
engine-mounted fuel filter. Conditioned fuel is then
pumped to the fuel injectors.
The fuel injection system is direct common rail. The
system includes a high-pressure fuel pump, fuel rail
and fuel injectors. The injectors are installed in the
cylinder head under the valve cover.
The MaxxForce® 15 engine uses dual turbochargers
with an air-to-liquid Interstage Cooler (ISC) between
turbochargers,
and a chassis-mounted air-to-air
Charge Air Cooler (CAC) to reduce air temperature
before entering the intake.
The cold start assist system warms the incoming
air supply before, during, and a short period after
cranking to aid cold engine starting and reduce white
smoke during warm-up.
The Exhaust Gas Recirculation (EGR) system
circulates cooled exhaust into the intake air stream in
the mixing duct. This cools the combustion process
and reduces the formation of Nitrogen Oxides (NO
X
)
engine emissions. The EGR cooler assembly cools
the exhaust gas in two stages.
An open crankcase breather system uses an oil
separator to return oil to the crankcase and vent
the crankcase gasses to the atmosphere. The oil
separator is mounted on the cylinder head.
The engine brake is standard on the MaxxForce® 15.
The engine brake is a compression release system
that provides additional vehicle braking performance.
The operator can control the engine brake for different
operating conditions.
Optional Features
An oil pan heater and a coolant heater are available
as optional cold climate features. Both heaters use an
electric element to warm engine fluids in cold weather
conditions.
The oil pan heater warms engine oil to ensure
optimum oil flow to engine components.
The coolant heater warms the engine coolant
surrounding the cylinders. Warmed engine coolant
increases fuel economy and aids start-up in cold
weather conditions.
Chassis Mounted Features
The aftertreatment system, part of the larger
exhaust system, processes engine exhaust so that
it meets tailpipe emission requirements. Most of the
aftertreatment system is mounted on the chassis.
• The Pre-Diesel Oxidation Catalyst (PDOC)
and Diesel Oxidation Catalyst (DOC) which is
mounted on the chassis, oxidizes hydrocarbons
and carbon monoxide, provides heat for exhaust
system warm-up,
and aids in temperature
management for the Diesel Particulate Filter
(DPF) for passive DPF regeneration.
• The DPF temporarily stores carbon-based
particulates then oxidizes the particulates and
stores the noncombustible ash.
The High-Pressure Charge Air Cooler (HPCAC)
mounted on the vehicle cooling module, is connected
between the outlet of the high-pressure turbocharger
and the inlet to the engine throttle valve assembly.
The HPCAC is an air-to-air cooler that uses ambient
air to cool pressurized air before it enters the engine.