SHIM 2G3221 - Caterpillar

Always verify fuel dilution. Obtain a S O S oil analysis in order to evaluate the condition of the engine oil.Note: For additional information, refer to , REHS3007, "Determining the Cause of Fuel Dilution of Engine Oil".Probable Causes
Injector
Leaking seals
Fuel injector tipFuel Transfer Pump
Fuel transfer pump sealCylinder Head
Cracked cylinder headRecommended Actions
Note: The procedures have been listed in order of probability. Complete the following procedures in the order that is provided.Leaking Seals
If leakage is found, remove the injector from the affected cylinder and visually inspect the injector's O-ring seals for damage. If damage is found, replace the damaged seals. Install the injector onto the engine and confirm that the repair has resolved the problem.If leakage is found and the O-rings are in good repair, there may be a problem with the injector. Replace the injector. Ensure that the new trim files are installed. Refer to Troubleshooting, "Injector Trim File - Install" for details.If the leakage is not located, add the appropriate dye to the fuel tanks. Run the engine at high idle for several minutes. Shut down the engine and remove the valve covers. Use a black light to check for traces of dye around each injector.If leakage is suspected for a specific injector, remove the injector from the affected cylinder and replace the damaged seals. Install the injector onto the engine and return the engine to service.Fuel Injector Tip
Use Cat ET to perform the "Cylinder Cutout Test" in order to identify any cylinders that may be overfueled. A fuel injector tip that is broken or fractured is a possible cause of a cylinder that is being overfueled. If a cylinder is identified by the test, Remove the injector and check the injector tip for damage. Check the fuel injector tip for cracks or breakage. If necessary, replace the suspect unit injector.Fuel Transfer Pump Seal
Check for fuel leakage around the shaft seal for the fuel transfer pump. Ensure that the weep hole is not plugged. If necessary, replace the fuel transfer pump.Cracked Cylinder Head
Look for signs of damage to the internal passages in the cylinder head for the fuel supply to the injectors. Check for pin hole leaks. Refer to Disassembly and Assembly.