• Aftertreatment Device (ATD)—a muffler-like can-
ister that houses a DPF and sensors.
• Diesel Particulate Filter (DPF)—a filter that col-
lects and holds particulate matter (soot and
ash).
• Diesel Oxidation Catalyst (DOC)—oxidizes hy-
drocarbons and reduces NOx.
• Sensors—detect temperatures and pressure
within the ATS.
• Diffuser—a device, used as a deflector, for dis-
tributing, mixing, and reducing the velocity of air
flow.
Inspection
IMPORTANT: The Environmental Protection
Agency’s 2007 regulations require lower ex-
haust emissions, thus requiring new exhaust
system components. See
Fig. 2. In particular
the aftertreatment device (ATD), which is part of
the aftertreatment system (ATS), requires spe-
cial attention during regularly scheduled mainte-
nance inspections. If any discrepancies are dis-
covered, refer to the engine manufacturer’s
service literature for repair instructions.
1. Check for leakage at the clamp that attaches the
exhaust pipe to the turbocharger exhaust outlet.
If leakage exists, tighten the nut on the clamp to
the required torque. If leakage persists, install a
new clamp.
2. Check the exhaust pipe, bellows, and each ex-
haust seal clamp for leakage, wear, cracks, or
damage. Replace damaged components as
needed. If leakage exists at a clamp, tighten the
nuts to the required torque. If leakage persists,
install a new exhaust seal clamp. Do not reuse
seal clamps. Once a seal clamp is loosened or
removed, it must be replaced.
3. If present, check the condition of the insulation
material around the exhaust pipe between the
turbocharger and the ATD, as well as the ex-
haust wrap from the ATD to the diffuser.
4. Check the ATD mounting bands for tightness.
Tighten to 30 lbf·ft (41 N·m) if needed. Do not
overtighten.
5. Check for leaks around the clamps that attach
the ATD in the ATS, and around the clamps that
retain the DPF in the ATD. No leaks are allowed
anywhere in the system.
6. Check all sensors attached to the ATD for leaks
or damaged wires. No leaks are allowed.
7. Check the DPF exterior surface for dents or
other damage. See
Fig. 2, Item A. A dent over 3
inches (76 mm) in diameter and 1/4-inch (6-mm)
deep could cause internal damage to the DPF,
causing it to malfunction.
8. Check for heat discoloration on the surface of
the ATD. Heat discoloration may indicate internal
damage; especially around the DPF.
9. Check any wires, lines, or hoses within 4 inches
(10 cm) of the exhaust system for heat damage.
Repair or reroute as needed.
Exhaust 49
Recreational Vehicle Chassis Maintenance Manual, November 2015 49/3
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