Checking the freedom of movement of the air damper servo drive (BMW 5 Series E12)

The freedom of movement of the air damper servo can be checked on the car or on a removed carburetor. In the latter case, the carburetor must be placed in a horizontal position.

Move needle 1 of the idle air jet down. At the same time, air damper valve 2 should close.

If this does not happen, disconnect the connecting rod 3 and check whether the air damper servo moves freely. If it is jammed, replace the servo. When installing a new servo after connecting rod 3, pay attention to the position of the groove and the locking lug (shown by arrows in the photo) and the 4 air damper drive lever.