FITTING 8D0538 - Caterpillar

Engine: C27 All C32 AllIntroduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is found, use the solution that is identified below.Problem
The source of the internal fuel leaks can be difficult to identify, once fuel dilution is identified by the oil analysis lab.Note: Injectors are not the only source of fuel dilution. Refer to Special Instruction, REHS3007, "Determining the Cause of Fuel Dilution of Engine Oil" for all components that can lead to fuel dilution.Solution
The following causes are listed below, if fuel dilution is noted at the first oil sample and is consistently noted throughout the following oil samples. These symptoms should be seen in the first 500 hours of operation.
Plunger to bore mismatch on one or more of the injectors
Loose CCV/Solenoid due to low torque at the factory
Top O-ring on the injector cut at factory installation
Plunger bore scratches from the factoryReplace the O-ring and return the engine back to service if a cut O-ring is observed. A new injector must be installed if a cut O-ring is not observed, because the plunger to bore can be mismatched or the CCV/Solenoid can be loose.
The following cause is listed below, if fuel dilution is not noted until after the engine has been in service for more than 1000 hours.
Deteriorated top injector O-ringReplace the top injector O-ring and install the same injectors.Refer to Special Instruction, REHS3007, "Determining the Cause of Fuel Dilution of Engine Oil" for more information.Note: This article is only an additional reference to Special Instruction, REHS3007, "Determining the Cause of Fuel Dilution of Engine Oil". Use Special Instruction, REHS3007, "Determining the Cause of Fuel Dilution of Engine Oil" in order to diagnose fuel dilution issues.