Fig. 3 Ventilating CV boot
WARNING: This page is about a different car, the 2024 Audi S6 and 2024 Audi A6 Quattro. However, it is still accessible from the selected car via links, so may be relevant.
Attaching the CV joint boot onto the outer body of the joint frequently requires compressing or squeezing the boot. This produces a vacuum in the joint boot, which may cause a crease to the inside when driving (arrow).
For this reason, after installing the joint boot, vent it briefly by letting some air in at the small diameter end, thus creating a pressure balance and restoring the correct boot shape.