0397374 JOHNSON DRIVE ASSEMBLY

The engine ECM calculates the amount of fuel in the engine oil based on the engine operating conditions and the number of Diesel Particulate Filter (DPF) active regenerations since the last time the "Engine Oil Life Reset" was performed.Note: Before continuing with this procedure, ensure that the engine oil has been changed according to the maintenance schedule. Refer to Operation and Maintenance Manual, "Maintenance Interval Schedule". If the engine oil has been changed, ensure that the "Engine Oil Life Reset" is performed. Refer to Operation and Maintenance Manual, "Engine Oil and Filter - Change".Measuring Fuel Dilution
Diesel fuel is chemically similar to the lubricants that are used in diesel engines. A slow fuel leak will blend the fuel into the oil. Normal operating temperatures may cause volatile parts of the fuel to vaporize. The fuel that remains in the oil is less volatile.A closed cup flash test can be performed in order to detect fuel dilution. The flash test is designed to measure the volatile parts of the fuel that are remaining in the oil. Detecting less volatile fuel is difficult. The less volatile fuel reduces the accuracy of the flash test.Since the flash test does not accurately detect fuel dilution, do not use the flash test as the only measure of fuel dilution. Instead, verify the dilution by the following methods:
Gas chromatograph fuel dilution test
Oil viscosityThe test that uses a gas chromatograph is designed to measure fuel dilution in crankcase oils. The gas chromatograph can identify the small chemical differences between diesel fuel and lubricating oil. A gas chromatograph is used to measure fuel dilution at all Caterpillar regional SOS laboratories. Some Cat dealers also use a gas chromatograph. Even though the gas chromatograph provides a more accurate measure of fuel dilution, always verify the results with the viscosity test.A significant level of fuel dilution reduces oil viscosity. If an unacceptable level of fuel dilution is suspected, the kinematic viscosity of the oil must be measured.Fuel dilution that is greater than 10 percent will usually cause viscosity that is less than the specified viscosity grade. If the oil is still within the specified viscosity grade, fuel dilution has not reached an unacceptable level.Verifying Fuel Dilution
Verify fuel dilution by the combination of low oil viscosity and a gas chromatograph that gives a result in excess of 10 percent before investigating or servicing the engine. Ask the Cat dealer to submit an oil sample to a Caterpillar regional SOS laboratory for analysis if a fuel dilution test cannot be performed locally.Probable Causes
Diagnostic codes
Maintenance interval schedule
Excessive use of active regeneration (wall flow DPF only)
Fuel injector seals
Fuel injector tipRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 2
Troubleshooting Test Steps Values Results
1. Diagnostic Codes
A. Connect the electronic service tool to the diagnostic connector.
B. Use the electronic service tool to check for an active 5055 diagnostic code.
Diagnostic codes
Result: A 5055 diagnostic code is active.
Proceed to Test Step 2.
Result: A 5055 diagnostic code is not active.
Proceed to Test Step 3.
2. Maintenance Interval Schedule
A. Use the electronic service tool to check the number of hours since the last "Engine Oil Life Reset" was performed.
B. Compare the number of hours since the last "Engine Oil Life Reset" to the maintenance interval for an oil change. Refer to Operation and Maintenance Manual, "Maintenance Interval Schedule".
Greater than oil change interval
Result: The number of hours since the last "Engine Oil Life Reset" is greater than the maintenance interval for an oil change.
Change the engine oil and perform the "Engine Oil Life Reset". Refer to Operation and Maintenance Manual, "Engine Oil and Filter - Change".
Result: The number of hours since the last "Engine Oil Life Reset" is less than the maintenance interval for an oil change.
Proceed to Test Step 3.
3. Excessive Use of Active Regeneration
Note: This step is only applicable to engines equipped with a wall flow DPF.
A. Excessive use of active regeneration may cause excessive fuel in the engine oil. Refer to Troubleshooting, "Diesel Particulate Filter Active Regeneration Occurrence Is Excessive".
Excessive regeneration
Result: There is excessive use of active regeneration.
Make any necessary repairs. Refer to Troubleshooting, "Diesel Particulate Filter Active Regeneration Occurrence Is Excessive".
Change the engine oil and perform the "Engine Oil Life Reset". Refer to Operation and Maintenance Manual, "Engine Oil and Filter - Change".
Result: There is no excessive use of active regeneration.
Proceed to Test Step 4.
4. Fuel Injector Seals
A. Check for signs of damage to the seals for the fuel injectors.
Fuel injector seals
Result: Injector seals are damaged.
Replace any damaged injector seals.
Change the engine oil and perform the "Engine Oil Life Reset". Refer to Operation and Maintenance Manual, "Engine Oil and Filter - Change".
Result: All injector seals are OK.
Proceed to Test Step 5.
5. Fuel Injector Tip
A. Check for signs of damage to the fuel injectors. Check the fuel injector tip for cracks or breakage.
Fuel injector tip
Result: A fuel injector is damaged.
Replace the fuel injector. Refer to Disassembly and Assembly, "Electronic Unit Injector - Remove" and Disassembly and Assembly, "Electronic Unit Injector - Install".
Change the engine oil and perform the "Engine Oil Life Reset". Refer to Operation and Maintenance Manual, "Engine Oil and Filter - Change".
Result: All fuel injectors are OK.
Contact the Dealer Solution Network (DSN).