49–00 Safety Precautions
Safety Precautions in this section apply to all
procedures within this group.
DANGER
When working on the vehicle, shut down the en-
gine, set the parking brake, and chock the tires.
Before working under the vehicle, always place
jack stands under the frame rails to ensure the
vehicle cannot drop. Failure to follow these steps
could result in serious personal injury or death.
49–01 Exhaust System
Inspecting (Noise
Emission Control)
In addition to inspecting the exhaust system at the
scheduled maintenance interval, inspect the exhaust
system if the noise level of the vehicle has in-
creased. Freightliner Trucks recommends replacing
parts that show leakage, wear, or damage, with
genuine Freightliner parts.
The exhaust system must be free of leaks, binding,
grounding, and excessive vibrations. These condi-
tions are usually caused by loose, broken, or mis-
aligned clamps, brackets, or pipes. If any of these
conditions exist, check the exhaust system compo-
nents and alignment. Align or replace as necessary;
see
Group 49
of the
Business Class® M2 Workshop
Manual
, or take the vehicle to an authorized Freight-
liner dealer.
It is a violation of US federal law to alter exhaust
plumbing or aftertreatment in any way that would
bring the engine out of compliance with certification
requirements. (Ref: 42 U.S.C. S7522(a) (3).) It is the
owner’s responsibility to maintain the vehicle so that
it conforms to EPA regulations.
EPA10 and Newer Exhaust
System
Definitions of Aftertreatment (ATS)
Terms
Refer to the following list of definitions of ATS terms
and components.
•
Aftertreatment System (ATS)—the entire ex-
haust system from the turbocharger to the ex-
haust stack or tail pipe.
•
Aftertreatment Device (ATD)—a housing that
contains the DOC and DPF (also the SCR and
the mixing tube in one-box systems).
•
BlueTec®—Daimler’s proprietary SCR technol-
ogy.
•
Diesel Oxidation Catalyst (DOC)—a flow-
through device that oxidizes soot in the ATD.
•
Diesel Particulate Filter (DPF)—a component in
the ATD that traps soot from the exhaust gas.
•
Diesel Exhaust Fluid (DEF)—the chemical agent
that reacts with the exhaust gases in the SCR
to reduce NOx.
•
DEF Pump—filters and supplies DEF to the
DEF metering unit.
•
DEF Tank—holds DEF and regulates its tem-
perature.
•
DEF Metering Unit—mixes DEF with com-
pressed air, and meters this mixture into the
exhaust flow via an injection nozzle.
•
SCR Catalyst—the housing containing a treated
ceramic flow-through block where the DEF and
exhaust gases undergo selective catalytic re-
duction (SCR).
•
Selective Catalytic Reduction (SCR)—a process
used to reduce NOx emissions.
Inspection
To meet EPA10 emissions regulations for vehicles
domiciled in the USA or Canada, engines manufac-
tured after December 31, 2009 are equipped with an
emission aftertreatment system. Vehicles domiciled
outside of the USA and Canada may not have after-
treatment equipment, depending upon local statutory
emissions guidelines.
IMPORTANT: The aftertreatment device (ATD),
which is part of the aftertreatment system (ATS),
requires special attention during regularly
scheduled maintenance inspections. No leaks
are allowed anywhere in the system. If any dis-
crepancies are discovered, refer to the engine
manufacturer’s service literature for repair in-
structions.
Exhaust
49
Business Class M2 Maintenance Manual, November 2015
49/1
Property of American Airlines
