Inspection After Removal

• Remove any residual gasket material from the flanges on the DPF and DOC assembly inlet and outlet using a suitable tool (A).

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  WARNING: Do not drop fragments of gasket material into the DOC and DPF assembly.
• Inspect all boss threads for damage.
• If thread damage is found on the sensor boss threads, repair threads or replace component as required.
  NOTE: If the DOC and DPF assembly is being inspected due to progressive damage that introduced engine oil or excessive fuel into the exhaust, inspect the exhaust downpipe from the turbocharger outlet to the DOC and DPF assembly. Refer to Exploded View .

DOC Inlet Inspection 

Inspect for the following potential failure modes:

1. Soot build up and DOC inlet face plugging

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   1. Face Plugging - If front face of the DOC inlet is 50% or more plugged, perform the following steps:
   • Interview customer to determine vehicle drive patterns (vehicle duty cycle). Large amounts of drive time at idle or low speeds may not allow thorough cleaning of the DOC and DPF assembly while driving.
     1. Perform Aftertreatment DPF Regeneration Test and inspect DOC inlet. Refer to Aftertreatment DPF Regeneration Test .
        NOTE: If face of DOC inlet is still 50% or more plugged, replace DOC and DPF assembly.
     2. Inform customer of the need to drive vehicle at higher speeds and loads per Owner's Manual when Exhaust Filter Overload message appears on the dash message display.
   • Investigate engine for history of a coolant leak from engine into the exhaust.
     1. Identify any current or prior coolant loss and repair source of coolant leak.
     2. Perform Aftertreatment DPF Regeneration Test to get the after treatment temperatures high enough to evaporate coolant from all after treatment components and clean out the system. Refer to Aftertreatment DPF Regeneration Test .
   • Fuel system or combustion issue - excessive soot may build up on the inlet to the DOC and DPF if there is an issue with fuel system or combustion components.
     1. Follow troubleshooting on any DTCs related to fuel system, air handling or engine components. Make repairs as needed per the troubleshooting.
     2. Perform Aftertreatment DPF Regeneration Test, refer to Aftertreatment DPF Regeneration Test .
2. Melted or deformed cells on DOC inlet - Any group of cells that no longer appear as a uniform cross hatch pattern, but have become cracked, dislodged or deformed.

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   • Check for fault codes related to high exhaust temperatures.
   • Inspect engine, turbocharger outlet, exhaust pipes and after treatment for evidence of excessive fuel or oil contamination.
     NOTE: Replace DOC and DPF assembly after related engine issues have been identified and resolved.
3. Cracking of DOC inlet surface - Inspection shows cracks on the face of DOC inlet.

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   • Troubleshoot and resolve any engine or after treatment DTCs or issues.
     NOTE: Replace DOC and DPF assembly after related engine issues have been identified and resolved.

DPF Outlet Inspection 

Inspect for the following potential failure modes:

1. Coolant staining - Inspection shows medium to dark shadows showing up on the surface of the DPF outlet (may be small or large shadows).

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   1. Investigate engine for history of a coolant leak from engine into the exhaust.
      1. Identify any coolant loss and repair source of coolant leak.
      2. Perform Aftertreatment DPF Regeneration Test to get the after treatment temperatures high enough to evaporate coolant from all components and clean out the system. Refer to Aftertreatment DPF Regeneration Test .
2. Soot staining - Inspection shows black soot stains on the channels of the DPF outlet.
   1. This indicates DPF has internal cracking or melting.
      1. Check for DTCs related to after treatment system.
      2. Investigate engine service history. Determine if fuel or lubricating oil has been introduced into exhaust as the result of damage to another engine component.
      3. Inspect turbocharger turbine outlet and after treatment inlet for lubricating oil or fuel.
         NOTE: Replace DOC and DPF assembly after cause of excessive black smoke, fuel, or lubricating oil in exhaust has been corrected.
3. Inspection shows thermal damage to DPF outlet.

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   1. Inspection shows loose segments of the catalyst material. Inspection shows missing channel plugs and missing cement sections of the catalyst.
   2. Inspection shows white powdery substance present.
   3. Inspection shows melted or deformed cells on the surface of the DPF outlet.
      1. Check for fault codes related to after treatment system. Investigate engine service history.
      2. Determine if fuel or lubricating oil has been introduced into exhaust as the result of damage to another engine component.
         NOTE: Replace DOC and DPF assembly after cause of excessive temperature has been corrected.
4. Cracking of DOC outlet surface - Inspection shows cracks on the face of DOC outlet.

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   1. Examine DPF outlet for surface or deeper cracks of the cement lines between the segments.
      • Possible causes are mishandling or impact damage.
        NOTE: Replace DOC and DPF assembly.
   2. Examine DPF outlet for cracks across the filter face.
      • High soot load in after treatment DPF reacted rapidly with engine exhaust, creating a high temperature.
        NOTE: Replace DOC and DPF assembly.