92 300E air pump

[RDMosley]

I just purchased a 92 300E with 127k miles on it. There is a moderate grinding noise under the hood. One shop says it is Alternator bearings, another shop says it is air pump bearing. I have listened and tend to think it is the air pump.

After reading some of the threads here I have several questions.

1) What is the best source for a used or rebuilt air pump?

2) Is replacing the air pump a do it yourself job?

3) I have read that the air pump is not really necessary for the performance on the car and can be disabled. Can anyone send me instructions on how to disable it?

Thanks so mucg for the help

Richard