Injectors

GENERAL INFORMATION

Faulty injectors can cause severe engine knocking and damage to bearings. In case of such faults, let the engine idle and loosen the injector union nuts one at a time in sequence. If knocking stops when one union nut is loosened, this indicates a faulty injector.

A faulty injector can also be located by loosening the union nuts one at a time in sequence while the engine runs at fast idle. If the engine speed does not change when a union nut is loosened, the corresponding injector is faulty. The injector can be tested with a pressure gauge (performed in a workshop). Required injection pressure: 120–140 bar.

The first signs of injector faults are: – misfiring of cylinders; – knocking in one or more cylinders; – engine overheating; – loss of engine power; – excessively black exhaust smoke; – high fuel consumption.

Removal

PROCEDURE

1. Carefully clean the high-pressure fuel lines and return fuel lines on the outside with cold cleaner or diesel fuel.

2. Remove the high-pressure fuel lines as a set. To do this, loosen the union nuts on the pump and injectors with a flare-nut wrench. Hold the fittings with an open-end wrench at the same time. Do not change the bend shape of the lines.

Warning: After removing the fuel lines, plug the openings with suitable plugs to prevent dirt and foreign objects from entering.

3. Disconnect the return fuel hose.

4. Unscrew the return line nuts.

Warning: Hold the line by its hex with a wrench, otherwise it may bend or break.

5. Remove the return line.

6. Unscrew the injectors with a socket wrench and lay them out in installation order. If necessary, mark the injectors with tape so they can be installed in their original positions.

7. Cover the injector openings to prevent foreign objects from entering.

8. Remove the injector gaskets. The gaskets must always be replaced.

Warning: Never clean injectors or injector needles with wire or a file. Do not mix up individual injector components. Installation

PROCEDURE

1. Clean the injector bores in the cylinder head and be sure to install four new heat-resistant gaskets. The recess must face up. The arrow points toward the cylinder head.

2. Install the injectors and tighten to 70 N·m.

Warning: Overtightening injectors may deform them, which in turn can cause the needle to stick or other faults.

3. Install the return line with four new gaskets and tighten the nuts to 45 N·m.

Warning: Hold the line from turning with a wrench while tightening.

4. Install the high-pressure fuel lines and tighten the union nuts to 25 N·m. Hold the fittings from turning.

5. Loosen the high-pressure line union nuts slightly at all injectors.

6. Crank the engine with the starter until fuel comes out of the high-pressure lines.

7. Tighten the union nuts to the specified torque.

8. If necessary, bleed the fuel system with the hand primer pump.