Recently purchased a rebuilt AAV from a gentleman who seems to know what he's doing. Went to replace mine, which seemed to be passing air when the engine was hot,to the point that I couldn't get the idle down with the air screw. Decided to compare them, immersing the bulbs in two identical cans filled with tea kettle water. Both closed fully and then, when the hot water was removed, retracted at the same rate and to the same point. Both bulbs were marked -30º.

The only difference was that his rebuild had a triangular opening to pass air and mine has a slightly larger square opening. My engine has always raced when cold, so I put a partial block in the hose leading to the AAV to control that. But, since both units operate identically as far as opening and closing, I'm wondering if my original might be the wrong part (for djet Mercedes or VW).

Does anyone know the proper Bosch P/N for the AAV on my 1970 1800E? Mine is 0 280 140 022. The rebuild is marked 013, but since it's a rebuild and only the guts are critical, I can't really go by that.