0331758 JOHNSON SCREW, Air silencer

Probable Causes
Active codes and logged codes
Fuel quality
Fuel system
Fuel injectors
Lubrication
Valve train
Gear train and components of the lower end
GovernorRecommended 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 and Logged Codes
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.
Note: Wait at least 30 seconds in order for diagnostic codes to become active.
   
Codes
   
Result: A code is active or logged.
Repair: Troubleshoot any codes before continuing with this procedure.
Verify that the repair eliminated the problem.
Result: A code is not active or logged.
Proceed to Test Step 2.
   
2. Check the Fuel Quality
A. Refer to Operation and Maintenance Manual 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. Refer to Systems Operation/Testing and Adjusting, "Fuel Quality - Test" for the proper procedure.
B. Cold weather adversely affects the characteristics of the fuel. Monitor the status screen on Cat ET in order to verify that the engine has exited cold mode (if applicable). Observe the reading for coolant temperature on the Cat ET.
   
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. Inspect the Fuel System
Refer to Systems Operation/Testing and Adjusting, "Fuel System" for additional information.
A. Check for the proper operation of the fuel transfer pump.
   
Fuel
   
Result: The fuel system is OK.
Proceed to Test Step 4.
Result: The fuel system is NOT OK.
Repair: Make the necessary repairs.
Verify that the repair eliminated the problem.
   
4. Test the Fuel Injectors
If service has been performed on the engine fuel system recently, verify that the injector trim files are correct. Use Cat ET to check that the injector trim files are correct for the injectors that are installed on the engine.
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.
   
Fuel Injector
   
Result: The test was successful.
Proceed to Test Step 5.
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.
   
5. Inspect the Governor Parameters
   
Parameters
   
Result: The governor parameters need adjustment.
Repair: Adjust the parameters for the governor in order to maintain stability.
Verify that the repair eliminated the problem.
Result: The governor parameters do not need adjustment.
Proceed to Test Step 6.
   
6. Check for Proper 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.
C. Inspect the engine oil filters for ferrous material.
D. Obtain an S-O-S oil analysis. The analysis will contribute to a better understanding of oil contamination and the origin of the contamination.
   
Lubrication
   
Result: The oil passages are not blocked and the engine has proper lubrication.
Proceed to Test Step 7.
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.
   
7. 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 8.
Result: The valve train components are damaged.
Repair: Make the necessary repairs.
Verify that the repair eliminated the problem.
   
8. Inspect the Gear Train and Components of the Lower End
   
Gear Train
   
Result: The gear train or lower end components are damaged.
Repair: Replace any damaged parts.
Verify that the repair eliminated the problem.
   If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).