PLUG 7L2123 - Caterpillar

Probable Causes
Active codes, logged codes, and electrical connector
Fuel quality
Injectors
Lubrication
Valve train components
Gear train and components of the lower endRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in the order of the listed test steps.
Table 1
Troubleshooting Test Steps Values Results
1. Check for Active Codes, Logged Codes, and Electrical Connectors
A. Establish communication between Caterpillar Electronic Technician (ET) and the Electronic Control Module (ECM).
B. Monitor the diagnostic codes on Cat ET. Check for active diagnostic codes and logged codes. Specifically check for codes related to the prelubrication system.
Note: Wait at least 30 seconds in order for diagnostic codes to become active.
Codes and Electrical Connectors
Result: A diagnostic trouble code is not active or logged.
Proceed to Test Step 2.
Result: A diagnostic trouble code is active or logged.
Repair: Check for correct installation of the applicable electrical connectors.
Troubleshoot any active codes before continuing with this procedure.
Verify that the repair eliminated the problem.
2. Check for Low Quality Fuel
A. Refer to Operation and Maintenance Manual and Application and Installation Guide, LEBW4977, "Gaseous Fuels" for information on the proper characteristics of the fuel for the engine. If necessary, obtain a fuel analysis in order to confirm that the correct fuel is being used for the engine.
Fuel
Result: The fuel quality is OK.
Proceed to Test Step 3.
Result: The fuel quality is NOT OK.
Repair: Replace the fuel.
Verify that the repair eliminated the problem.
3. Check the Fuel Injectors
A. Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.
B. Access the "Cylinder Cutout Test" in the "Diagnostic Tests" under the "Diagnostics" menu.
C. Perform the "Automatic Cylinder Cutout Test" on Cat ET.
Injector Solenoid Test or Cylinder Cutout Test
Result: The test was successful.
Proceed to Test Step 4.
Result: The test was not successful.
Repair: Diagnose the problem and then repair the problem.
Reset all active codes and clear all logged codes.
Verify that the repair eliminated the problem.
4. Check for Lack of Lubrication
A. Check for proper lubrication of the valve components. Check for sufficient lubrication between the injector tappets and the rocker arms.
B. Check for blocked oil passages. Oil passages must be clean. Clean any oil passages that are questionable. Refer to the Disassembly and Assembly for additional information.
Lubrication
Result: The oil passages are not blocked and the engine has proper lubrication.
Proceed to Test Step 5.
Result: The oil passages are blocked or the engine does not have proper lubrication.
Repair: Make the necessary repairs.
Verify that the repair eliminated the problem.
5. Inspect the Valve Train Components
A. Check the valve lash. Refer to Troubleshooting, "Valve Lash Is Excessive".
B. Check for damage to valve train components. Remove the valve cover from the suspect cylinders. Check the following items for damage:
- Camshaft
- Valve rotocoil
- Valve springs
- Camshaft followers
- Rocker shaft
- Bridges
- Pushrods
- Injectors
Refer to the Disassembly and Assembly for additional information.
C. Check for valves that do not move freely. Remove the cylinder head and inspect the valves.
Refer to the Disassembly and Assembly for additional information.
Valve Train
Result: The valve train components are not damaged.
Proceed to Test Step