10
ENGINE SYSTEMS
Heavy Duty On Board Diagnostics (HD-OBD)
The EPA has added new regulations for 2010 to
reduce heavy duty vehicle emissions. The HD-OBD
system is designed specifically for electronically
controlled heavy duty engines. The goal for HD-OBD
regulation is to keep engine emissions in specification
for as long as a given vehicle is in use.
HD-OBD is legislated to be implemented in three
phases:
•
2010: First engine for each Original Equipment
Manufacture (OEM) becomes fully certified.
•
The lead engine is determined by a legislated
equation based on projected sales volume &
useful life of the engine.
•
For Navistar®, this is the EPA 2010
®
N13
engine.
•
2013: One engine in each engine family becomes
fully certified.
•
This will be the largest step of the three
phases.
•
2016: All engines must be fully HD-OBD certified.
The HD-OBD system continuously monitors for proper
engine operation, and will alert the vehicle operator to
emission-related faults using the Malfunction Indicator
Lamp (MIL).
The MIL is installed in the Electronic Instrument
Cluster.
When a detected emissions fault occurs,
the MIL will be illuminated. Diagnostic information is
also stored in the Engine Control Module (ECM), and
may be accessed by the technician for diagnosis and
repair of the malfunction. Diagnostic information is
accessed by connecting the Electronic Service Tool
(EST) to the in-cab Diagnostic Connector.
Engine Description
The Navistar
®
N13 diesel engine is designed
for increased durability, reliability, and ease of
maintenance.
The cylinder head has four valves per cylinder for
increased airflow. The overhead valve train includes
rocker arms and valve bridges to operate the four
valves. The fuel injector is centrally located between
the four valves, directing fuel over the piston for
improved performance and reduced emissions.
The overhead camshaft is supported by seven
bearings in the cylinder head.
The camshaft gear
is driven from the rear of the engine. The overhead
valve train includes roller rocker arms and dual valves
that open, using a valve bridge.
Navistar
®
N13 engines use one-piece steel pistons.
All pistons use an offset piston axis and centered
combustion bowls.
Crown markings show correct
piston orientation in the crankcase.
The one-piece crankcase uses replaceable wet
cylinder liners that are sealed by dual crevice seals.
The crankshaft has seven main bearings with fore
and aft thrust controlled at the sixth bearing. One
fractured cap 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.
A gerotor lube oil pump is mounted behind the front
cover and is driven by the crankshaft. Pressurized
oil is supplied to various engine components.
All
Navistar
®
N13 engines also use an engine oil cooler
and a cartridge-style engine oil filter, which are
installed in the engine lube oil module.
The low-pressure fuel pump draws fuel from the
fuel tank(s) through a chassis mounted filter/water
separator. The low-pressure fuel pump provides fuel
for the engine mounted fuel module.
Conditioned
low-pressure fuel is supplied from the engine mounted
fuel module to the high-pressure fuel pump, Inlet Air
Heater fuel solenoid, and the AFT fuel doser module.
The high-pressure fuel system is a direct fuel injected
common-rail system.
The common-rail includes a
high-pressure fuel pump, two fuel rail supply lines,
fuel rail, six fuel injectors, and pressure relief valve.
The fuel injectors are installed in the cylinder head
under the valve cover and are electronically actuated
by the ECM.
Navistar
®
N13 engines use a dual stage, fixed
geometry turbocharger assembly.
Each stage
includes a Charge Air Cooler (CAC). The High
Pressure (HP) turbocharger includes a pneumatically
operated wastegate. The Low Pressure Charge Air
Cooler (LPCAC) is mounted on the lower right side
of the engine, and uses the engine cooling system to
regulate charge air temperatures. The High Pressure
Charge Air Cooler (HPCAC) is mounted in front
