This internet thingy is kinda neat. My air injection pump ('90 300SEL) started rumbling, so I removed it and took it apart today. Very obvious that the clutch bearing was beginning to seize. I'm not sure of all the different models, but a lot of them appear to use a design with a proprietary INA bearing that costs around $200. No biggee.....I'll just go to the shopforum and find out how to repair and parts and.........WHAT? No references?

I googled for air injection info and what did I find? A link to this shopforum thread: 300E no reverse which shows this has been a saga for several others.

After searching, searching, linking, and more searching, it appears there is an exact replacement available from several sources. If you need a replacement bearing, this one ($19) should work: http://bearingsdirect.com/products/index.php?action=item&id=5114&prevaction=category&previd=56&prevstart=0

Thanks forum!