C2.4 Tier 4 Final Engines for Caterpillar Built Machines Caterpillar

Oil Contains Fuel

Usage:

Always verify fuel dilution. Ask the Caterpillar dealer to submit an oil sample to a Caterpillar regional SOS laboratory for analysis.

Note: For additional information, refer to Special Instruction, REHS3007, "Determining the Cause of Fuel Dilution of Engine Oil".

Probable Causes

Leaking seals
Fuel injector tip
Fuel transfer pump seal
Cracked cylinder head

Recommended Actions

Note: The procedures have been listed in order of probability. Complete the procedures in order.

Show/hide table

Table 1
Troubleshooting Test Steps	Values	Results
1. Diagnostic Codes A. Establish communication with Caterpillar Electronic Technician (Cat ET). Check for active diagnostic codes.	Diagnostic Codes	Result: Active diagnostic codes are present. Troubleshoot the diagnostic code 523602-0 High Frequency Regeneration code is active can cause fuel dilution. If this code is present refer to “Diesel Particulate Filter Active Regeneration Occurrence is Excessive”. Result: Active diagnostic codes are not present. Proceed to Test Step 2.
2. Oil Change Interval The oil should be changed at 500 hours.	Oil Change	Results: The oil does not exceed 500 hours excessively. Proceed to Test Step 3. Results: The oil exceeds 500 hours excessively. Perform oil sampling to ensure that fuel dilution is not flagged prior to the next 500 hour oil change interval.
3. DPF Nearing the 3,000 Hour Maintenance Interval	DPF Maintenance	Result: If nearing the 3,000 Hour DPF cleaning interval, then active regenerations (in cylinder dosing) will occur more frequently and this maybe normal.
4. Machine in a Low Load Application Refer to Performance Handbook for fuel burn for this model and compare to the fuel usage in the Product Status Report.	Low Load Application	Fuel dilution can occur in low load applications. Refer to Special Instruction, REHS3007, Duty Cycle of Machine Applications Requires a Reduced Oil Change Interval. In addition low load applications can result in more frequent active regenerations which can also cause fuel dilution.
5. Check the Fuel Injector Seals Check the seals to the injector and the seals for the injector return tube under the valve cover. 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.	Fuel Injector Seals	Result: A leak was found. Make the necessary repairs. Result: No leak is found. Proceed to Test Step 6.
6. Fuel Injector Tip A. Use Cat ET to perform the "Cylinder Cutout Test" to identify any cylinders that may be overfueled. B. A fuel injector tip that is broken or fractured is a possible cause of a cylinder that is being over fueled. 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.	Injector tip	Result: The fuel injector tip is damaged. Replace the suspect injector.

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).