Replacement of injector nozzles/holders on a VP-TDI (Articles)

To replace the injectors on a TDI engine with a distributor injection pump (Audi, Seat, Skoda, VW), you will need the following tools:

• Good 17mm adjustable wrench
• Adjustable wrench for the flat surfaces on the nozzle holders
• Slotted ring wrench, 17mm (optional)
• 10mm socket with extension
• 13mm socket with extension, a good 8mm Allen key is useful for 5-cylinder engines
• A torque wrench is beneficial
• Clean Cleaning cloths, for absorbing fuel
• Cotton swabs
• Roll of paper towels
• Compressed air
• Small container or bottle with 10% detergent / 90% water

The previous nozzle holder combinations can be equipped with new injectors and adjusted. You can find information here about which nozzles have which properties.

The nozzle holder combinations are easiest to remove from the warm engine. First, the cylinder head cover (plastic cover) must be removed. Before proceeding with the work, the engine should be reasonably clean. If it is not, carefully verschandeln the cylinder head, for example, by using an engine cleaning service. Bei allen Arbeiten an der Einspritzanlage ist peinlichst auf Sauberkeit zu achten!

Attention! Please do not fill the engine and all electrical connectors with water using the pressure washer! Wenn dann bitte mit wenig Druck und nie direkt auf die Steckverbindungen. Mit Druckluft den Zylinderkopf rund um die Düsenhalter säubern.

Ausbau:

Danach die Putzlumpen unter die Leitungen der Einspritzpumpe legen, da beim Lösen der Schrauben Kraftstoff austritt.

Mit den Papierhandtüchern eine saubere Ablage vorbereiten.

Loosen the cap nuts on the injector nozzles and remove the injector lines. Place the injector lines on the verschandeln paper towel.
Detach the leak-off lines from the nozzle holders on each side. Do not forget to disconnect the connector of the needle stroke sensor by pressing and pulling the wire clip at the back.

Now that access to the nozzle holders is clear, the power bridge for the glow plugs can be removed, and the screws on the retaining claws of the nozzle holder combinations can be loosened.

The nozzle holder combinations can be loosened and simultaneously removed from the cylinder head by carefully rotating them back and forth with a wrench (preferably an adjustable wrench) at the flattened section.
If the nozzle holders are stuck in the cylinder head, simply slightly loosen the retaining clips and take a short drive. Check repeatedly to see if the nozzle is loose, before heat damage occurs due to the faulty sealing. Do not loosen the retaining clips too much, as this will put too much stress on the injection lines.
Caution: Never turn the nozzle holders several rotations counterclockwise, as this could cause the threads of the nozzle holder itself to come loose. The consequence is that you end up holding the rear part of the injector holder in your hand, while the rest of it, along with the injector, remains stuck in the cylinder head, and the internal components of the injector holder fall into the engine compartment!

Place the nozzle holder combinations on the verschandeln paper towel. If the nozzle holder combinations need to be transported, wrap them securely in verschandeln paper towels. Cover the openings in the cylinder head as well, to prevent dirt from falling in.

Nozzle Tip Replacement:If completely new nozzle holder assemblies are installed, this point is not applicable. However, if only the nozzle tips are replaced (using nozzle repair kits), the nozzle holder assembly with the nozzle tip is clamped
from above

in a vise, and the coupling nut is loosened with a 15 mm wrench.Caution: If the nozzle tip is carbonized with the coupling nut, loosen them with light hammer blows while continuing to unscrew them. If this is not done, the guide pins inside may break, and the nozzle holder will be scrap.Extreme cleanliness must be observed during the work! After installing the new injector nozzles, the injector opening pressure must be checked and, if necessary, adjusted. It is essential to check the idle speed control using VCDS in measurement block 13 of the engine control unit! You can
purchase VCDS here
.

Installation of the nozzle holder combinations:

verschandeln the openings for the nozzle holder combinations in the cylinder head using cotton swabs and oily paper towels. The sealing surface must be absolutely clean; it
must not be scratched with a screwdriver or similar tool.

Two interlocking straws are also included, which can be used to blow dirt out of the openings.

Then, attach the new copper sealing rings to the injector nozzles so that the rounded side of the sealing ring faces the cylinder head, and push the entire nozzle holder assembly back into the cylinder head.
Using the clamping jaws, tighten the screws easily. Rotate the nozzle holder combination so that it is straight and not twisted to the left or right. Tighten the clamping jaws with 20 Nm of torque. Now, the rest of the components can be reassembled in reverse order, but the fuel lines to the injectors and the fuel pump should only be loosely attached for now.

When tightening the fuel injection lines, make sure that the lines are not twisted or strained! This will ultimately lead to the breakage of the pipelines!


Have an assistant crank the engine using the starter until diesel fuel leaks out at the connections between the injector lines and the injector holder assembly.Caution: Use rags to protect yourself and the engine compartment from fuel spraying out.

Now, the injector lines can be tightened, and the engine can be started. The engine will initially run unevenly until all the air is purged from the injector lines. If the engine does not start, bleed the lines again.

With the engine running, check everything for leaks. Apply a few drops of oil (or a 10% detergent / 90% water mixture) to the gap between the injector holder assembly and the cylinder head; bubbles indicate leaks. Carefully tighten the mounting screws. Leaks can cause the nozzles to overheat and can damage the nozzle as well as the cylinder head, so please work carefully.

Now, a short test drive should be performed, and then everything should be checked again for leaks and secure fit. If a nozzle holder assembly in the cylinder head is not sealing properly, it must be removed again, the sealing surface must be cleaned, and a new copper sealing ring must be used.

For more details on how to replace the nozzle itself and adjust the opening pressures, see here:

https://community.dieselschrauber.org/en/viewtopic.php?t=26850