Is there such a thing as maintenance of the air pump?

I have 3 mercedes, and replaced the air pump on 2. Is there somethings I can do to avoid this expense?

One of the relacements (140) was a used pump. Described as being in good shape - but used none the less. I was feeling broke that day.

Well, what can I do to mke the pump on the 140 and 107 chassie last longer?

Thank you very much

__________________
Thanks for the help
Bill Fisher

'86 560SL (186K) - Now a 'classic' : Registered as an Historic Vehicle
02 E430 in the stable
'14 LS460 (Lexus)
- - - - -
'95 E420 (198K) found a new home
'99 E320 (80K) (gave it's life for me as we hit a bumper)
'95 E420 (231K) Sold to a happy buyer, new to Mercedes
'90 300E (65K) Sold to an Mercedes Lover
'92 190E (215K) - retired to the salvage yard
'93 500SEL (214K) - Moved to another family, still runs like a young pup