VANOS Rattle Repair Kit, Beisan - E36, E34, E39, Z3

BS012

You can replace your Vanos seals but still have a Vanos rattle on M50, M52, S50, and S52 engines. The common rattle complaints come from play within the Vanos piston assembly. During a Vanos rebuild is the perfect time to open the piston and replace the ring that is most likely the cause of your Vanos rattle.

The Beisan M50-S52 anti-rattle ring are shorter than the original and with a tighter dimension tolerance and stricter quality control. The shorter height removes any gap in the stacked piston-bearing assembly. Ideally, there should be some pre-load and zero play in the assembled piston. For detailed instructions on the procedure, click here. The ring is made from a special bearing steel and hardened to a high material hardness. All surfaces are ground and polished to the correct dimensional tolerance.

The ring is at the very heart of the M50-S52 Single-VANOS system. Replacement is easy and straightforward but requires complete disassembly of the Vanos unit and then the Vanos piston. The ring houses two roller bearing plates, bearing spacer, and washers. The shorter ring height reduces the gaps between each of these components to eliminate any movement or play (thereby eliminating the rattle).

Note 1: Beisan recommends only using their Nylon vice jaw liners to hold the pistons during disassembly. They tested various jaw liners and found that only a special Nylon vice jaw liners was appropriate for clamping the soft aluminum Vanos pistons. Using aluminum or rubber vice jaws may damage the Vanos pistons.

Note 2: the hex on the Vanos piston is 17 or 18mm but only 3mm tall. However, most off-the-shelf sockets have a slightly larger opening so the socket will slide easily over a nut or bolt head. The short height of the hex makes it very easy for a standard socket to not full engage the flats and round off the corners. Beisan sells modified sockets that do not have the larger, chamfered opening., However it might be best to first check your socket's compatibility or cut the tip off an old or cheap socket. Early hexes were 17mm but BMW phased in a 18mm hex beginning in 1992.