Cummins ISX11.9 CM2250 – Service Manual 011-036   Aftertreatment Selective Catalytic Reduction (SCR) Catalyst

WARNING  The exhaust and exhaust components can remain hot after the vehicle stopped moving. To reduce the risk of fire, property damage, burns or other serious personal injury, allow the exhaust system to cool before beginning this procedure or repair and make sure that no combustible materials are located where they are likely to come in contact with hot exhaust or exhaust components.

CAUTION  The catalyst elements contained in the aftertreatment system are made of brittle material. Do not drop or strike the side of the aftertreatment system, as damage to the catalyst element can result.

Due to the number of varing exhaust aftertreatment applications, this procedure has been written to be generic. Not all illustrations within this procedure will represent the application being serviced.

Different vehicles will require different aftertreatment configurations.  Some of the aftertreatment SCR catalysts may have elbows clamped to them.

Variations in vehicle aftertreatment configuration will drive the use of different flanges. The clamps and gaskets on either end of the aftertreatment selective catalytic reduction (SCR) catalyst may be different from one another.  There are two types of flanged joints, full Marmon™ (1) and spherical Marmon™ (2).  The spherical Marmon™ joints allow a small amount of misalignment and have a rounded cross section.  The full Marmon™ joints are completely rigid and have a more edgy profile.

WARNING  Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.

WARNING  During regeneration, exhaust gas temperature could reach 800°C [1500°F], and exhaust system surfact temperature could exceed 700°C [1300°F], which is hot enough to ignite or melt common materials, and to burn people. The exhaust and exhaust components can remain hot after the vehicle has stopped moving. To avoid the risk of fire, property damage, burns or other serious personal injury, all the exhaust system to cool before beginning this procedure or repair and make sure that no combustible materials are located where they are likely to come in contact with hot exhaust or exhaust components.

WARNING  Wear appropriate eye and face protection when using compressed air. Flying debris and dirt can cause personal injury.

• Disconnect the batteries. Refer to the OEM service manual.
• Clean the area with compressed air to remove any loose debris.
• Draw an orientation reference line across each of the V-band and Torca™ clamps on either end of the aftertreatment SCR canister.  This will aid in lining up the clamps and canister to their original orientation during installation.
• Remove the NOx sensor. Refer to Procedure 019-451 in Section 19.

WARNING  This component or assembly weighs greater than 23 kg [50 lb]. To prevent serious personal injury, be sure to have assistance or use appropriate lifting equipment to lift this component or assembly.

Support the aftertreatment decomposition tube to prevent it from being freely suspended after the aftertreatment SCR catalyst is removed.  If supporting it is not an option, remove the aftertreatment decomposition tube. Refer to Procedure 011-062 in Section 11.

Support the aftertreatment SCR catalyst with a lowering jack.

Remove the clamps on either end of the aftertreatment SCR catalyst.

Remove the electrical connection attached to the aftertreatment SCR catalyst temperature sensor interface module.

Remove the exhaust hangers that support the aftertreatment SCR catalyst and slowly remove the canister from the vehicle.

Discard the gasket from the V-band joint.

If the aftertreatment SCR catalyst is being replaced, complete the following procedures to remove the key parts of the aftertreatment SCR catalyst.

Disconnect the aftertreatment SCR catalyst temperature sensors (1) from the aftertreatment SCR catalyst temperature sensor interface module (2).

Remove the aftertreatment SCR catalyst temperature sensors (1). Refer to Procedure 019-449 in Section 19.

Remove the aftertreatment SCR catalyst temperature sensor interface module (2). Refer to Procedure 019-464 in Section 19.

Remove the aftertreatment SCR catalyst temperature sensor interface module mounting bracket (3). Refer to Procedure 011-076 in Section 11.

CAUTION  Do not use a metallic object to clean the aftertreatment SCR catalyst.  This will scratch the surface of the aftertreatment SCR catalyst which may cause future excessive diesel exhaust fluid crystallization buildup.

Inspect the aftertreatment SCR catalyst for cracks or puncture holes, especially around the weld areas.

Replace the aftertreatment SCR catalyst if it is damaged.

Inspect the aftertreatment SCR catalyst inlet for diesel exhaust fluid deposits.

If buildups are present, carefully scrape the buildup with a non-metallic object to clean the majority of the buildup from the catalyst.

NOTE: Do not use a pressure washer to remove diesel exhaust fluid deposits from the aftertreatment SCR catalyst.

NOTE: If crystallization buildup was present after installation, complete a stationary regeneration to make sure that any of the remaining diesel exhaust fluid crystallization has been removed from the aftertreatment SCR catalyst.

Inspect the exhaust flanges for corrosion or other damage.

Use a putty knife to remove any residual gasket material from the flanges on the aftertreatment SCR catalyst.

Avoid dropping fragments of gasket material into the aftertreatment SCR catalyst. 

Do not grind on the flange surface, as this can damage the flange and cause the connection to leak.

Inspect the V-band clamps and mounting straps for signs of over extension.

The V-band must not be bent or damaged.

Inspect the V-band clamp and mounting strap threads for damage.

Replace the V-band clamp or mounting strap if damage is found.

Install the aftertreatment SCR catalyst temperature sensor interface module mounting bracket (3). Refer to Procedure 011-076 in Section 11.

Install the aftertreatment SCR catalyst temperature sensor interface module (2). Refer to Procedure 019-464 in Section 19.

Install the aftertreatment SCR catalyst temperature sensors (1). Refer to Procedure 019-449 in Section 19.

Connect the aftertreatment SCR catalyst temperature sensors (1) to the aftertreatment SCR catalyst temperature sensor interface module (2).

WARNING  This component or assembly weighs greater than 23 kg [50 lb]. To prevent serious personal injury, be sure to have assistance or use appropriate lifting equipment to lift this component or assembly.

CAUTION  Do not use an air tool to tighten the V-band clamp. An air tool will damage the threads.

Place the aftertreatment SCR catalyst on the vehicle. Use the exhaust hangers to support the canister.

Align the catalyst in the same orientation as marked previously.

Horizontal aftertreatment SCR catalysts incorporate a water drain hole in the outlet section of the canister. If a new horizontal aftertreatment SCR catalyst is being installed, make sure the drain hole is located toward the bottom of the installation, within ±10 degrees of the vertical axis.

Apply a coat of anti-seize compound on the threads of the V-band clamp. Put a new gasket on the V-band connection of the aftertreatment SCR catalyst and install opposite of removal. Tighten the V-band and Torca™ clamps.

NOTE: Where applicable, install and tighten the full Marmon™ clamps before the spherical Marmon™ clamps, to account for misalignment in the aftertreatment system.

Tighten the exhaust hangers. Refer to the OEM service manual for specifications.

WARNING  Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.

• Connect the batteries. Refer to the OEM service manual.
• Start the engine and check the system for leaks.
• Use INSITE™ electronic service tool to check for active fault codes.
• If buildups were present, complete a stationary regeneration to make sure that any of the remaining diesel exhaust fluid crystallization has been removed from the aftertreatment SCR catalyst.
• Continue to monitor for leaks at the exhaust joints.