Initial Inspection and Diagnostic Overview

AFTERTREATMENT INSPECTION GUIDELINE

Figure 1 - EXHAUST SYSTEM - 6.7L DIESEL - P/U

Figure 2 - 6.7L DIESEL- CAB CHASSIS

Overview
This service document provides visual inspection guidelines for the after treatment systems used in Cummins 6.7L powered Dodge Ram vehicles. This includes both Pickup truck, model years 2007-Present (2500 & 3500 Series) and Cab Chassis model years 2007-2010 (4500 & 5500 Series). For removal and installation procedures, refer Exhaust System. The After treatment systems are uniquely different for the Pickup truck and Chassis Cab. Above are diagrams of both systems.

1. PICKUP OR CAB CHASSIS VEHICLE

Is the vehicle a Pickup or Cab Chassis frame?

Pickup

- Go To 2

Cab Chassis

- Go To 5

2. PICKUP VEHICLE INSPECTION OF THE DIESEL PARTICULATE FILTER (DPF)

NOTE: The primary failure modes for the DPF are inlet face plugging, internal cracking and internal melting. Inlet face plugging is easily diagnosed. Internal cracking and melting can be identified by soot patterns on the DPF outlet and/or evidence of soot on the outlet tail pipe.

1. Remove the DPF from the vehicle.
2. Inspect the inlet face of the DPF.

NOTE: DPF Inlet is the flanged side.

3. This figure is an example of a failed DPF due to severe face plugging. All inlet channel openings are completely plugged. Symptoms would possibly include hard or no start and/or related P-codes.

4. This figure is an example of a good DPF inlet. Note that immediately following a regeneration event, the inlet face will/may look cleaner. Also note that it is normal for the inlet face to be coated with soot. Inlet channels should be open and visible. As long as cell matrix is visible the inlet is ok.

5. Inspect the outlet of the DPF.
6. This figure is an example of a failed DPF due to an internal melting of cells. The DPF outlet face and pipe show evidence of soot. Symptoms can include Black Smoke, and/or related P-codes.

7. This figure is an example of a failed DPF due to an internal cracking of the substrate. The DPF outlet channel openings show evidence of soot. Close inspection shows several blackened channel openings or "black cells. Also Outlet pipe shows evidence of soot. Symptoms can include Black Smoke, and / or related P-codes.

8. This figure is an example of a failed DPF due to a leak at the DPF Outlet rim of substrate. Look for black cells on the outlet face.

9. This figure and the next are examples of a good DPF. In this figure, it is not black or does not show any black cells. Note orange appearance near weep hole at bottom. This is dirt ingestion from dusty areas that does not affect filter performance. Outlet pipe is not sooty as compared to a failed part. Normally outlet face is off white or tan in appearance.

10. This figure shows an enlarged section with a small black circle near the center of substrate. This is the only sign of soot evident in the entire outlet inspection. A quick check with a 1'' socket will show pass/fail of this part. Using a one inch socket (1.375 inches Outer Diameter) and extension, cover the black spot at the center of DPF outlet face. If the 1 inch socket covers the black spot and no other black cells are visible, DPF doesn't need to be replaced. If there are any black cells visible around the 1 inch socket, DPF does not meet pass criteria and should be replaced. If there are any black cells on other portions of the outlet face in addition to a black spot in the center, DPF should be replaced.

NOTE: Make sure one inch socket has about 1.375 inches of outer diameter (Standard socket not impact). DPF outlet thermistor may be removed, if it is in the path of the black spot.

Does the DPF show signs of face plugging, internal cracking or melting?

Yes

- Replace the Diesel Particulate Filter.

No

- Go To 3

3. INSPECTION OF THE NOx ABSORBER (NAC) ON A PICKUP

NOTE: The primary failure modes for the DPF are inlet face plugging, cracking and internal melting. Inlet face plugging is easily diagnosed (would resemble the figure showing face plugging of the DPF).

1. Remove the NAC from the vehicle for inspection.
2. Inspect the inlet side of the NAC.
3. This figure and the next are examples of a good NAC. The inlet shows no signs of face plugging, melted spots, or cracks on the face of the grid. A typical NAC inlet will be coated with soot. The inspection process is to verify that light can be seen through the cells. If light can be seen through the cell matrix then the part is good.

4. This figure is a zoomed view to show close pictures of wash-coat spots. Typically the size of these spots are 3/16''. These are not due to melting and does not require replacement.

Does the NAC show signs of face plugging, internal cracking or melting?

Yes

- Replace the NOx Absorber (NAC).

No

- Go To 4

4. INSPECTION OF THE DIESEL OXIDATION CATALYST (DOC)

NOTE: The DOC inlet is the only portion that can be inspected easily. Key modes of failure are FACE plugging, debris and possibly melted channels.

1. This figure is an example of a good DOC. Soot is present on the inlet which is normal. As long as cell matrix is visible the inlet is ok.

Does the DOC show signs of face plugging, internal cracking or melting?

Yes

- Replace the Diesel Oxidation Catalyst (DOC).

No

- Test complete.

5. CAB CHASSIS VEHICLE INSPECTION OF THE DOC/DPF (DIESEL OXIDATION CATALYST AND DIESEL PARTICULATE FILTER)

NOTE: The inlet side to the DOC/DPF on the Cab Chassis is the Catalyst portion. It resembles the Pickup NAC in appearance. The outlet side is the Diesel Particulate Filter portion. This functions exactly the same as the DPF on the pickup truck. Because they are combined, only the inlet of the DOC and outlet of DPF on the cab chassis can be inspected.

1. Remove the DOC/DPF from the vehicle for inspection.
2. Inspect the DOC inlet. Look for signs of FACE plugging, debris and possibly melted channels.

NOTE: The DOC inlet can be identified by a "diffuser" leading into the inlet.

3. This figure and the next are examples of a good DOC. The inlet shows no signs of face plugging, melted spots, or cracks on the face of the grid.

4. This figure is a zoomed view to show close pictures of wash-coat spots. Typically the size of these spots are 3/16''. These are not due to melting and does not require replacement.

8. This figure is an example of a failed DPF due to a leak at the DPF Outlet rim of substrate. Look for black cells on the outlet face.

10. This figure shows an enlarged section with a small black circle near the center of substrate. This is the only sign of soot evident in the entire outlet inspection. A quick check with a 1'' socket will show pass/fail of this part. Using a one inch socket (1.375 inches Outer Diameter) and extension, cover the black spot at the center of DPF outlet face. If the 1 inch socket covers the black spot and no other black cells are visible, DPF doesn't need to be replaced. If there are any black cells visible around the 1 inch socket, DPF does not meet pass criteria and should be replaced. If there are any black cells on other portions of the outlet face in addition to a black spot in the center, DPF should be replaced.

NOTE: Make sure one inch socket has about 1.375 inches of outer diameter (Standard socket not impact). DPF outlet thermistor may be removed, if it is in the path of the black spot.

Does the DOC/DPF appear to be face plugged, melted or have any internal cracking?

Yes

- Replace the DOC/DPF.

No

- Test complete.