TURBO GP-BASIC 10R8948 - Caterpillar

Testing and Procedures
Fuel Dilution Troubleshooting Procedure
Reports indicate that some dealers may be using inaccurate test procedures when troubleshooting for fuel dilution of the lube oil on 3406B Engines. In some cases, the results of the tests performed may be misinterpreted. In other cases, the most likely causes are being overlooked. When troubleshooting for fuel dilution of the lube oil, use the procedures that follow in the sequence given.1. Verify fuel dilution.2. Test internal fuel lines.3. Check fuel injection nozzles.4. Test fuel transfer pump.5. Test fuel injection pump housing.Verify Fuel Dilution
Fuel dilution of the lube oil can be verified by two methods. First, by the test results of an S O S (Scheduled Oil Sampling). Second, by an increase in the oil level. If the second method is used, make sure the increase in the oil level is due to the addition of fuel.Internal Fuel Lines
To test the internal fuel lines, it will be necessary to use the 5P-4150 Nozzle Testing Group and two lengths of wire braided hose capable of withstanding a pressure of at least 20,700 kPa (3000 psi). Use Special Instruction SEHS7292 for instructions on using the 5P-4150 Nozzle Testing Group.Modify the two lengths of wire braided hose as follows:1. Install a 6V-3989 Nipple on one end of each hose. This end will be connected to the nozzle tester with a 6V-4143 Coupler Assembly (Quick Disconnect).2. Weld a section of fuel line and its nut to an appropriate fitting. Install this fitting on the end of one hose.3. Weld an appropriate fitting to the bottom of a 2W-3409 Fuel Pump Bonnet. Install this fitting on the end of the second hose.Check for internal leaks as follows:1. Remove both valve covers and valve cover bases.2. Wipe off all internal fuel lines, fuel injection nozzles, and/or nozzle adapters.3. Disconnect one end of an external fuel line. Disconnect the end that is easier to work with.4. Use the appropriate hose to connect the 5P-4150 Nozzle Testing Group to the external fuel line or to the fitting on the cylinder head fuel line adapter. This will make it possible to pressurize the internal fuel line and fuel injection nozzle.5. Close the on-off valve, and open the isolation valve on the tester. Pump the handle rapidly until a pressure of 20,700 kPa (3000 psi) is obtained. Close the isolation valve.6. Check for leaks at the areas shown in Illustrations 2 and 3.
Illustration 2. Location to check for internal fuel leaks with 1W-2950 or 7W-1902 Adapters.
Illustration 3. Locations to check for internal fuel leaks with 7W-1645 Adapter.7. Repeat Steps 3 through 6 for all the cylinders.Fuel Injection Nozzles
To check the fuel injection nozzles for leaks, remove the nozzles from the engine. Do not remove the bleed screws. Apply a pressure of 20,700 kPa (3000 psi) to the nozzle with the 5P-4150 Nozzle Testing Group. Check the nozzle for leaks in the areas shown in Illustration 3. Observe for 4 to 5 minutes. Small leaks are not readily apparent in the typical 1