380 Diesel Engine Technology Copyright Goodheart-Willcox Co., Inc. Align the nozzle spacer locating pins with the pin holes in the holder body and assemble the spacer into the body. If the spacer has a beveled edge, it should face toward the nozzle. Dip the nozzle valve in clean cali- brating or lube oil, and assemble the valve to the nozzle body. The valve must be free in the body. Check by lifting the valve about one-third of its length out of the body. Hold the assembly at a 45° angle and release the valve. It should slide freely back down into the body. If needed, work the valve into the body with clean mutton tallow. Measure the lift height of the nozzle valve to be sure it is within specifications. Incorrect lift heights will affect liftoff time, fuel flow, and the spray cone and pattern. To measure the lift height, place the spindle of a depth dial indicator against the upper shoulder of the nozzle valve. Zero the dial and then place the spindle against the face of the nozzle body. The difference on the dial reading indicates the lift height of the nozzle valve. If the lift height is greater than specified, you can bring it into specifica- tions by lapping the face of the nozzle body. The nozzle assembly can also be replaced. Apply a thin even coat of lubricant to the nozzle body seating shoulder and align the nozzle body locating pin holes with the spacer pins. Assemble the nozzle to the spacer. Assemble the cap nut over the nozzle and tighten the cap nut by hand. Reinstall the injector in the fixture and place the appropriate size box torque adapter wrench onto the cap nut before turning in the fixture securing bolt. Tighten the cap nut to the required torque. Install a nozzle gasket to the nozzle. Testing and Adjustment Perform an opening test, chatter test, seat leakage check, spray pattern check, and back leakage test as described earlier in this chapter on all cleaned and reas- sembled injectors. Injector nozzles that fail these tests after cleaning should be replaced. Set the correct opening pressure as listed in the manufacturer’s service manual. When new springs have been installed, the opening pres- sure should be set about 50 psi (345 kPa) higher than the manual spec to allow for initial settling of the spring. Installation The injector bore in the cylinder head must be thor- oughly cleaned before the injector is reinstalled. Good cleaning cannot be overemphasized in any phase of fuel injection service. The slightest bit of dirt on nozzle mounting surfaces can cause combustion gas blowby or cocking of the nozzle that can result in sticking. Sometimes, special reamers are used to clean carbon from the injector bore. Be sure to use a new nozzle gasket. Do not use lubricants during installation unless the service manual procedures call for it. Only use the recom- mended lubricants in the manner described. When lubri- cants are used improperly, they can turn to carbon under the intense heat of combustion and cause removal prob- lems the next time the injector is serviced. Figure 18-25 illustrates a typical nozzle installed in the cylinder head. Nozzle holder Nozzle holder locating pin (part of nozzle holder) Injection nozzle holder O-ring seal upper Injection nozzle holder O-ring seal (1) lower omit Nozzle holder clamping screw Nozzle fuel inlet tube sleeve Nozzle fuel inlet tube clamping screw Nozzle fuel inlet tube sleeve Nozzle fuel inlet tube sleeve nut Nozzle fuel inlet tube Nozzle fuel inlet tube collar Fuel drain passage (nozzle leak off) Injection nozzle holder insert Injection nozzle holder gasket Injection nozzle Cylinder head Figure 18-25. Typical nozzle installed in the cylinder head deck. Be sure to leave the fuel line loose to allow air to escape. (Mack Trucks, Inc.)