Western Star 47X 2020, Maintenance Manual

Page: 147 / 166

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
Maintenance
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 Western Star 47X and 49X
Workshop Manual .
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.
No visible exhaust gas leaks are allowed any-
where in the ATS. If any problems are discov-
ered, refer to the engine manufacturer’s service
literature for repair instructions.
NOTE: Diesel exhaust fluid creeps, causing
white crystals to form around the line fittings.
The presence of crystals does not mean the
system has a leak. Replacing fittings or trouble-
shooting components is not necessary unless
there is a system failure or a fault code.
1. Check the DEF tank, pump, metering unit, and
lines for leaks. See
Section 49.02 of the West-
ern Star 47X and 49X Workshop Manual for re-
pair procedures.
2. Check any wires, lines, or hoses within 4 inches
(10 cm) of any uninsulated part of the exhaust
system for heat damage. Repair or reroute as
needed.
Diesel Exhaust Fluid (DEF) Filter
Replacement
The Selective catalytic reduction (SCR) uses diesel
exhaust fluid (DEF) to lower NOx emissions in the
vehicle exhaust. A filter in the DEF pump prevents
clogging of the DEF metering unit injection nozzle.
Twist the filter cover to replace the filter. See
Fig. 1 .
See the engine manufacturer’s maintenance manual
for filter replacement instructions intervals.
f490577 04/30/2020
1 2
3
4
5
6
7
1. DEF Pump
2. Water Supply Valve
3. DEF Pump Bracket
4. Tir-Fir Tree Mount
5. DEF Suction Line
6. Coolant Return Tube
7. DEF Filter Cover
Fig. 1, DEF Pump, Cummins Engine
Exhaust
49
47X and 49X Maintenance Manual, August 2020
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