GEAR-DIFFERENTIAL BEVEL 6W8259 - Caterpillar

Probable Causes
Active codes and logged codes
Low quality fuel
Injectors
Lack of 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 order.Complete the procedure in the order in which the steps are listed.
Table 1
Troubleshooting Test Steps    Values    Results    
1. Active Codes and Logged Codes
A. Establish communication between Caterpillar Electronic Technician (ET) and the Electronic Control Module (ECM).
B. Download the "Warranty Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes.
   
Codes
   
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: Troubleshoot the active or logged codes.
   
2. Low Quality Fuel
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 System Quality Test" for the proper procedure.
   
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. Injectors
C13, C15, and C18 Applications
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.
C9.3 Applications
A. Perform the "Fuel System Verification Test" in the "Diagnostic Tests" under the "Diagnostics" menu.
   
Injector Solenoid Test or Fuel System Verification 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. 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. 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:
1. Camshaft
2. Valve rotocoil
3. Valve springs
4. Camshaft followers
5. Rocker shaft
6. Bridges
7. Pushrods
8. 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: