Killer Crawdaddy 01 S4

Been doing some preventative maintenance on my 2001 s4 and i need a little advice. i am currently replacing my aux. water pump,(which by the way , why is there not a single after market company whom makes the pump housing held on with the four Phillips head screws)? I was hoping to find an aluminum machined version , but scratch that. Either way my main question is concerning the cam chain tensioners. Can they be rebuilt,cleaned ect. I mean they are rediculously priced. Mine are just getting a little noisy and while i am under the hood i would really like to take care of this now. Also is there a way to check used ones for proper operation? I am a lifelong mechanic whom refuses to deal with dealers especially audi dealers "friggin rip off bastards" thank you for your time !

Peter Badore

For the chain tensioners you could just replace the plastic chain
guides and then monitor their advance and retard function with VAG-COM.
The adjusting mechanism can have a long life in my experience if the engine is well maintained with synthetic oil, good filters and performed more frequently than Audi's 10,000 oil change interval.