C175 Tier 4 Final Engines for Off-Highway Trucks Clean Emissions Module Inspection and Recovery Caterpillar

Safety

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Do not operate or work on this product unless you have read and understood the instruction and warnings in the relevant Operation and Maintenance Manuals and relevant service literature. Failure to follow the instructions or heed the warnings could result in injury or death. Proper care is your responsibility.

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Hot parts or hot components can cause burns or personal injury. Do not allow hot parts or components to contact your skin. Use protective clothing or protective equipment to protect your skin.

Machine Preparation

1. Drive the machine onto a smooth level surface that can support the weight of the machine.

2. Ensure that the parking brake is active, and all the work tools are laid on the ground.
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   Illustration 1	g06502755

3. Perform Lockout Tag Out procedure by attaching a warning tag to the machine controls.

References

Reference: Troubleshooting, M0069788, "Exhaust Has Excessive White Smoke"

Reference: Troubleshooting, M0069788, "Oil Consumption Is Excessive"

Reference: Troubleshooting, M0069788, "Oil Pressure Is Low"

Reference: Troubleshooting, M0069788, "SCR Catalyst Inlet Pressure Is High"

Introduction

Use this procedure only after an event occurred which potentially contaminated the Clean Emissions Module (CEM) catalyst with fuel, oil, or coolant. Only use this procedure when directed by the Troubleshooting manual.

Procedure

1. Disassemble and inspect exhaust flex lines. Remove any loose debris, liquid substances (Oil, Fuel, Coolant), inspect bellows for mechanical damage caused by foreign object impact.

   • Replace damaged components.
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   Illustration 2	g06526647
   Clean Emissions Module (CEM) inlet cross section (1) Inlet NOx sensor (2) DEF injector (3) Inlet mixer (4) Inlet temperature sensor

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   Illustration 3	g06526648
   CEM inlet - Duel CEM (1) Inlet NOx sensor (2) DEF injector (3) Inlet mixer (4) Inlet temperature sensor

2. Inspect the Clean Emissions Module (CEM) inlet. Inspect the mixer fins and CEM walls. Remove any loose debris, liquid substances (Oil, Fuel, Coolant). Loose or damaged mixer fins may come loose during operation and damage other components including the turbocharger. DEF deposits appear as a white film or patch of small crystals are acceptable and can be ignored. Large three-dimensional accumulations of DEF may indicate a DEF system problem which has been accumulating over time. A large DEF deposit is not the result of fuel, oil, or coolant being introduced into the exhaust system.

   • Replace damaged components which may include the CEM inlet assembly, or entire CEM depending on application.

   • Inlet mixers are not serviceable and cannot be repaired nor replaced individually.

3. Inspect CEM inlet. Inspect DEF injector / Nozzle tip (2) for damage or DEF deposits. Inspect inlet NOx sensor (1) and temperature sensor probe (4). The CEM inlet pressure sensor is remotely mounted from the exhaust flow. The sampling port protrudes into the exhaust flow and may be fouled with deposits or liquid oil or fuel. The NOx sensor probe cannot be cleaned, the sensor must be replaced.

   • NOx sensors with deposits or have been contaminated with liquid oil, fuel or coolant must be replaced.

   • Replace temperature sensor if the probe in the exhaust stream has 3-dimensional deposits. (More than surface adherence) Light soot deposits are normal.

   • DEF deposits on injectors may be removed by gentle cleaning. The injector may be removed and cleaned by soaking the tip in warm water. The injector must be replaced if the tip is damaged in any way.

4. Return the unit to operational condition. Follow all work site pre-start procedures. Be sure that the engine may be started safely before operating the machine.

5. Upon starting the engine, inspect as necessary to ensure that the engine and machine are operating properly. Ensure that all guards and safety equipment are installed and working correctly.

6. Return to operation procedure:

   1. Monitor CEM inlet temperature via Cat^® Electronic Technician (Cat ET) Service Tool or Machine Display and observe exhaust outlet.

   2. Run engine at idle or elevated idle. The CEM inlet temperatures of 250° C (482° F) to 300° C (572° F) are ideal to evaporate excess hydrocarbons on the catalyst. However, just running exhaust flow through the system slowly evaporates some excess hydrocarbons on the catalyst.

   3. Observe tail pipe and expect to see white smoke. If white smoke appears, continue to run until the white smoke clears. If no white smoke is observed, proceed to Step 7.

   4. If running in cold ambients or if the catalyst hydrocarbon contamination level is low, white smoke may not appear at idle. If no white smoke is observed after 15 minutes, proceed to Step 7.

7. Run the "Aftertreatment System Functional Test (ASFT)".

   1. Monitor the exhaust temperature and observe the exhaust outlet monitoring for visible white smoke. The ideal temperature to remove excess hydrocarbons is 250° C (482° F) to 300° C (572° F). During at least a portion of the ASFT the automatic loading cycle will cause exhaust temperatures to reach these temperatures.

   2. Repeat as many times as necessary to clear observable white smoke.

   3. If ASFT passes with no white smoke and no-fault codes, go to Step 8.

   4. After completely following the troubleshooting steps without finding an issue, the catalyst may have been damaged requiring overhaul of the CEM.

   5. Codes that will typically remain active if the catalyst is damaged are:

      • Low NOx Conversion

      • Low DEF Concentration

      • Pressure drop across the CEM is excessively low

      • Pressure drop across the CEM is excessively high

   6. If catalyst damage is suspected, the CEM must be removed from the chassis and the catalyst must be replaced.

   7. Once the CEM is repaired, rerun "Aftertreatment System Functional Test" to verify proper function.

   8. If ASFT is successful, go to Step 8.

   9. If ASFT is not successful, and the catalyst has been replaced, follow the troubleshooting steps as necessary to resolve the issue. Once ASFT is successful, go to Step 8.

8. Return to service, monitor for unusual smoke or aftertreatment faults.