Diffuser Assembly; Diffuser Adjustment - PREVOST H3-41 Maintenance Manual

centered with the exhaust inlet of the
catalytic converter.
EXHAUST
INLET
While tightening the bolts, keep in mind to
•
respect the alignment of the parts and keep
the lower support as centered as possible
with the catalytic converter exhaust inlet.

5. DIFFUSER ASSEMBLY

During stationary regeneration, exhaust gases
temperature may get very hot at the outlet. The
diffuser decreases the exhaust gas temperature
by about half at 6 inches above the diffuser. The
diffuser is an important component of the
exhaust system and must remain on the vehicle
at all times. Operating the vehicle without the
diffuser may seriously damage the vehicle.
FIGURE 7: DIFFUSER ASSEMBLY

1.9. DIFFUSER ADJUSTMENT

Should an adjustment of the diffuser position be
necessary, first remove
aftertreatment roof ventilation grill.
CAUTION
To prevent paint damage and fiberglass
overheating caused by hot exhaust gases, the
diffuser louvered cover must be flush with the
SECTION 04 : EXHAUST AND AFTERTREATMENT
the exhaust
PA1621 Maintenance Manual All Series | Section 04 revised Feb 2019
roof surface or may not exceed the roof
surface more than 3/32 inch (2 mm).
CAUTION
Tighten clamps properly in order to prevent
any movement of the diffuser assembly. An
impact wrench is necessary.
1. Loosen the clamp securing the diffuser
assembly to the catalytic converter.
FIGURE 8: DIFFUSER POSITION ADJUSTMENT
2. For proper angular position, make sure that
the two edges shown on Figure 8 are parallel
with each other.
3. Using a straightedge, adjust the diffuser
assembly level. The top surface of the
warning plate fixed on the diffuser louvered
cover must be flush with the roof surface or
may exceed about 3/32in (2mm).
4. Tighten the clamp securing the diffuser
assembly to the catalytic converter.
5. Reinstall the EATS roof ventilation grill and
deflector.
1.10. MAINTENANCE
At vehicle inspection intervals, inspect the
diffuser assembly as follows:
• Inspect diffuser grille for stress cracking;
• Check for presence of foreign matter and
debris inside the diffuser housing, remove
and clean if applicable;
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