Caution: Take special precautions when working with fuel injectors. Never place your hands or other body parts under the fuel jet from the nozzle, as high operating pressure may cause fuel to penetrate the skin, possibly causing death. It is highly recommended that pressure injector testing be performed by a dealer or diesel fuel system specialist.
Examination
1. The condition of the injectors deteriorates with prolonged use, and it is quite possible to expect that after 100,000 km of mileage (or so) they will require repair or replacement. Accurate testing, repair and calibration of injectors should be entrusted to a specialist. A faulty injector that causes detonation or increased smoke can be identified without disassembling it by following these steps.
2. Allow the engine to idle at high speed. Loosen the connection on each injector one by one, after wrapping the connection with a rag to prevent fuel from spilling. Be careful not to let fuel come into contact with your skin. When the connection on the faulty injector is released, the detonation or smoking will stop.
Removal
3. For easier access on 1.9L models, remove the air distribution housing as described in paragraph 3. If necessary, also remove the air intake duct and disconnect the vent hose from the oil filler pipe. For more information, please refer to the relevant paragraphs in this chapter.
4. Thoroughly clean the area around the injectors and the union nuts of the injector fuel lines.
5. Disconnect the return fuel lines from the injectors (figure 10.5).
Figure 10.5. Disconnecting the return fuel line from the fuel injector
6. Unscrew the union nuts securing the fuel lines of the injectors to the high-pressure fuel pump. Hold the fittings on the pump while unscrewing the nuts. Plug open ports to prevent dirt from entering. For this you can use small plastic bags or "fingers" cut off from "old" ones (but clean!) rubber gloves.
7. Unscrew the union nuts and disconnect the fuel lines from the injectors (figure 10.7). If necessary, the fuel injector lines can be removed completely. Carefully mark the location of the fuel line clamps to facilitate installation. Cap the ports on the injectors to prevent dirt from entering.
Figure 10.7. Unscrewing the union nut on the injector fuel line
8. Unscrew the injectors using a long socket head or open-end wrench (for chamfers with a spanner size of 27 mm) and remove them from the cylinder head (figure 10.8).
Figure 10.8. Unscrew the injectors and remove them from the cylinder head
9. Remove the copper washers and flame deflector washers from the mounting holes in the cylinder head. Also remove the bushings if they are not secured (figure 10.9, a-c).
Figure 10.9, a. Removing the copper washer of the fuel injector...
Figure 10.9, b....flame-deflecting washer...
Figure 10.9, c....and bushings
Installation
10. Purchase new copper washers and flame washers. Also replace the bushings if they are damaged.
11. Do not allow the injectors to fall and be careful not to damage the injector tips. The injectors are manufactured to very precise tolerances and require careful handling. For example, never clamp them in a vice.
12. Begin installation by installing the bushings (if they were removed) into the cylinder head. Then install the flame deflector washers (convex side up) and copper washers.
13. Screw in the injectors and tighten them to the specified torque.
14. Install the fuel injector lines and tighten the union nuts. Install the fuel line clamps according to the previously marked position. If the clamps are not positioned correctly or are missing, problems may occur such as broken or cracked pipes.
15. Connect the return lines.
16. Reinstall the items removed to gain access (see the relevant paragraphs of this chapter).
17. Start the engine. If difficulties arise, bleed the fuel system as described in paragraph 2.