382 Diesel Engine Technology Copyright Goodheart-Willcox Co., Inc. Caution: Never use a pry bar to remove the nozzles as they are easily bent. Plug all holes to prevent contaminants from entering the engine. Both the carbon dam seal and the compression seal must be replaced whenever a pencil nozzle is removed from an engine. Failure to use a new carbon dam seal may result in very difficult subsequent nozzle removal. This is due to carbon escaping past the reused carbon dam and accumulating in the clearance between the nozzle body and its bore in the cylinder head. Be sure to cap the nozzle openings and fuel lines to prevent dirt from entering the engine and fuel system. Disassembly is not recommended for cleaning. The proper cleaning methods involves cleaning the nozzle exterior with solvent and then removing the carbon dam and upper dust seal. Submerge the tips of the nozzles in a parts cleaning solution and soak for at least 30 minutes, Figure 18-30. Do not submerge the nozzle completely. This would remove the anti-rust coating on the nozzle body. After soaking, inspect the nozzle holes for corrosion and clogging. Open clogged holes using a proper size cleaning wire. Clean the nozzle tip and seal groove with a brass wire brush. Pencil Nozzle Testing and Adjustment The following are the basic steps in testing and adjusting pencil nozzles. Prior to testing, remove the carbon dam seal from the tip of the nozzle with a razor blade or sharp knife, Figure 18-31. Then, remove the loose carbon from the tip of the carbon dam seal groove with a brass wire brush. Attach the nozzle to the nozzle tester using a special test pump adapter. Caution: Using a standard nozzle adapter will damage the flange of a pencil nozzle. Capped Pencil Nozzle A capped pencil nozzle, Figure 18-28 has no return fuel line like standard pencil nozzles. During injection, fuel accumulates in the nozzle cap rather than returning to the fuel tank. Between injections, the lower line pressure allows the pressurized return fuel in the cap to bleed past the valve to the injection line. Pencil Nozzle Removal Figure 18-29 illustrates a typical pencil nozzle instal- lation configuration. Always thoroughly clean the area around the injector before removal. Remove the hold- down nut. Disconnect the high pressure fuel lines and remove each nozzle by pulling upward with a slight twisting motion. Stubborn nozzles can be removed by using a puller designed for this task. Cleaning solution 200°F (93.3°C) Figure 18-30. Nozzles can be cleaned by soaking in a heated cleaning solution. (Stanadyne Diesel Systems) Injector nozzle Hold-down nut Supply line Figure 18-29. Typical pencil nozzle installation. (Stanadyne Diesel Systems) Cap Line Figure 18-28. A capped pencil nozzle does not use a return line. Leak-off fuel accumulates in the nozzle cap, and bleeds back into the injection line between injections. (Stanadyne Diesel Systems)