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Removing and Installing Fuel Injectors

The fuel injectors must be removed for inspection or testing. As described above, the injectors are held in the inserts by thick rubber O-rings. To remove the injectors simply pull them straight out, forcing them out of the O-rings, as indicated in Fig. 4-28. Leave the fuel lines attached. Pull straight and pull only on the injectors themselves, not on the fuel lines.

Fig. 4-28. Remove CIS, CIS-E, and CIS-E Motronic fuel injectors by pulling straight out (arrow). Pull on injector body only, not on fuel line.

NOTE-

Some force is required to remove the injectors, and an inexpensive special tool is available which makes the job easier. It fits under the injector fitting and uses a screwdriver for leverage, prying the tool and the injector straight out. One such tool is Volkswagen special tool no. US 1123/4 (order no. TU1 123 004 25 SCP).

It is not normally necessary to remove the injector inserts, except to replace the O-rings and cure air leaks which can cause rough idling. The inserts have an internal hex-shaped socket and are removed using a hex wrench-12 mm or 13 mm depending on the application. The sealing O-rings should be replaced whenever the inserts are removed. See Fig. 4-27 above. Moisten the O-rings with fuel before installing. Clean the threads of the upper insert and install using Loctite® T primer and Loctite® 620 thread locking compound, or equivalent. Torque the upper injector insert to 20 Nm (15 ft. lb.).

Injector installation is the reverse of removal. The thick rubber O-rings should always be replaced. Soak the new ones in fuel for several minutes before installing them. Then press the injector into the insert until the O-ring is fully seated in its groove.

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