Avoiding cylinder head damage in unit injector TDI engines: Optimum problem solution with 07eins PDE body holder

Cylinder head damage in Volkswagen Group (VW, Audi, Skoda and Seat) TDI engines with pump-injector elements ("PDE") built between 1998 and 2010 is frequently caused by loosening PDE seats, which can work their way into the cylinder head and thus lead to leaks and even cylinder head damage. The ORIGINAL 07eins PDE body holder (repair holder) solve the cause lastingly and permanently, unlike competitor products. Thus, defective cylinder heads in TDI diesel engines are a thing of the past. In combination with the 07eins reinforced VITON sealing rings, the diesel engine receives maximum protection against fuel mixing into the oil circuit.

A detailed overview of the 07eins PDE body holders is available atPump Nozzle Unit Body Holder / PDE Repair Holder for VW, Audi, Seat, Skoda TDI can be found.

The damage ("run-in marks") in the seats of the Bosch unit injectors bolted on one side, which occurs in the cylinder head exclusively on the opposite side of the bolting, is caused by the original retaining shoes tilting sideways when they are tightened.

The force caused by the one-sided bolting of the retaining shoes presses the PDEs onto theopposite inner side of the PDE seats, because the engagement in the groove on the injector is at some distance next to the screw connection:

VW has also taken this problem into account from the outset and, on closer inspection, has provided the retaining shoes with an overhang at their upper edge, with which the retainer is supported against tilting on the cylinder head. In addition, the bore was widened towards the bottom in order not to load the screw with a bending moment.

During the development of the PDE TDI engines at that time, it was obviously not possible to correctly assess the extent of this support force, which basically leaves tangible and visible traces on this support surface in every cylinder head, over the service life of the TDI engines:

The counterpart of these worn-in surfaces is finally formed by the injector seats, which now have to withstand this introduced transverse force. In the course of operation under heat/cold cycling and vibration, the unit injectors work their way more and more into the cylinder head. After a prolonged period of operation, this leads to diesel interference and the resulting numerous consequential damages and engine running problems, up to and including complete cylinder head damage.

Non-optimal problem solution of the competitor product for TDI unit injector engines with higher mileage

If a loose bracket with an extended foot is now used on the other side of the injector, it will experience the identical tilting moment as the original retaining shoes (groove and support still sit laterally offset to the mounting screw).

Optimal problem solution with the ORIGINAL 07eins PDE body holders (repair holders) with support plates.

To counteract the tilting, the screw must absorb the force in a narrow bore that is normally diverted to the cylinder head.

The injector screw, which is already highly stressed, is not designed for such a force application. This overload can lead to complete cylinder head damage with longer running times and additional vibrations and thermal expansion.

This problem was taken into account in the development of the 07eins PDE body mount:

By bolting the body holder to the injector, a frictional connection to the pump-nozzle element is established. The tilting force that occurs is thus dissipated via the screwed wing into the body of the injector.

07eins PDE body holders (repair holders) permanently eliminate the cause of cylinder head damage in TDI engines with unit injector elements:

The bore for the expansion screw in the 07eins PDE body holders, as in the VW original, is designed so large that there is no contact and thus no bending force transmission to the thread.

This technical solution of the connection with the pump-nozzle element is protected in the DE utility model DE 20 2020 106 341 U1. For this reason, competitor products can use this optimal connection of PDE and repair holder.

But this is not enough. The transverse force now described several times is prevented with the connection to the PDE body. Nevertheless, there is still "only" a one-sided screw connection without de facto centering of the injector (as is also the case, of course, with surface-mounted solutions).

Another advantage of using the 07eins PDE corpus holders is that additional support plates are used to provide additional support.

Each cylinder head has a known, exact dimension of the lateral cylinder wall to the center of the PDE seat. The corresponding surface is machined and brought to size on each cylinder. VW has also used these surfaces, as described at the beginning, to support the retaining shoes.

The 07eins PDE body holders use this precise contact surface and, by applying this support gauge block, create a tolerance-compliant support connection with exact centering of the PDE.

Summary

The protected ORIGINAL 07eins PDE body holders eliminate the problem of TDI engines with unit injectors built between 1998 and 2010 by means of the friction-locked screw connection with the unit injector element. Solutions with one-piece body holders or repair holders do not offer this sustainable and permanent protection.