GTI TDI Timing Belt Pulley Issue: Broken on KW?

Hallo zusammen, bei einem Bekannten von mir ist die KW Schraube 'abgerissen' und die Riemenscheibe hat sich gelockert. Der Wagen ist einfach nicht mehr angesprungen, er lief vor dem letzten abstellen noch einwandfrei. Kompression hat der Motor noch, Ventile sind unbeschädigt (zum Glück!). Nachdem er das Fahrzeug in die Werkstatt gefahren hat, hat er gesagt bekommen, dass der Schaden nicht zu beheben sein. Ich habe leider nur die 3 schlechten Bilder hier. Kann mir jemand kurz erklären, wie das ganze aufgebaut ist? Die Kurbelwelle hat eine flache Stelle außen, damit die Riemenscheibe sich nicht auf der Welle drehen kann?! Ist die Riemenscheibe eine Scheibe für Zahnriemen und Keilriemen? Die Kurbelwellenschraube fixiert dann diese Riemenscheibe, damit die nicht nach außen kann. Ich verstehe momentan nicht, warum der Schaden ireperabel sein soll? Ich habe mit der Suchfunktion mehrere Fälle dieser abgerissenen KW-Schrauben gefunden, aber leider ohne Bilder und auch ohne konkrete Abhilfe?! Verwendet Ihr andere Schrauben oder hat VW das Problem erkannt und verbaut inzwischen andere Schrauben beim Zahnriemenwechsel? Or have I simply overlooked the relevant article?

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Pulley, a disc for timing belts and V-belts? The crankshaft bolt secures this pulley so that it cannot move outwards. I don't currently understand why the damage is supposed to be irreparable.

First, you should take and replace one or two better pictures.

The so-called crankshaft pulley consists of two parts: the crankshaft gear and the vibration damper (which is the actual pulley).

The KW sprocket is attached to the KW using the central screw. The resulting pressure between the two components (unfortunately, only achieved due to [thank you to the Murks team who were allowed to design this]) occurs between the two end faces. The flattening is actually only intended for the correct alignment of the KW and sprocket (in the past, a spring washer [wedge] was used for this).

If, for whatever reason, the central bolt comes loose, the flat surface of the components will be damaged. If only the gear is replaced, the pulley will start to wobble, and further damage is almost inevitable.

To prevent this, the front surface of the transmission will be re-ground to ensure complete contact and allow the parts to rotate smoothly.
For this purpose, Sauer offers a hand-held milling cutter that allows the repair to be carried out while the component is still installed.
Unfortunately, this is not always possible because the older versions of the torque wrench often have cracks in the torque wrench body near the socket, which are sometimes only visible with a magnifying glass.

Find a reputable engine builder and have them inspect or repair the issue.

Okay, great... thanks for the detailed answer. What about the screw? Should I use an original VW screw again? Does anyone know of a reputable workshop near Ludwigshafen that can perform the repair?

Hi,

I find it unlikely that the compression is okay... usually, two valves are bent.

The surface must be planed using specialized equipment, or the kiln (KW) must be dismantled and the surface planed by a qualified technician.

Then, install a new wheel with a new bolt, following the specified torque and angle (90 Nm + 90°).
The vibration damper (pulley) should usually be replaced as well, as the most common cause of failure is the degradation of the rubber layer.

Best regards, Michael.