with new bearings? or lubed up?
It sounds like a box of rocks, I hear it while driving. I spin it with no belt and it's rough.
I'll get a bypass pulley if not.

 

I bought a Cardone rebuilt from Advance AP for my 89. Around $100 exchange.

 

Yeah, it can be rebuilt. Trouble is finding the parts to rebuild it. Not readily available at a parts store, and doubtful they could get the parts even if by chance you were to find a diagram parts list. Gm lists it as a complete assembly. Maybe cardone can get you the parts to rebuild it?

 

Most states will let you upgrade it to an electric one.

 

I ended up doing the air pump lobotomy, the bearing was in good shape with no rust, greased it and the drum, quieter now let's see how it goes. The fins are some kind of layered composite, use a narrow chisel and easy to hack it off, which is a shame because that looks to be a nice piece of engineering in there. Not that it actually did anything in my case anyway..

 

92-96 lt1, or 88-95 zr1 electric pump would be a good upgrade on the l98 cars, but you would have to have the ecu programmed to turn it on and off. And making it emissions compliant would be the real struggle. I assume that's why you want to rebuild it? Cause if emissions testing isn't required just remove it, and use the delete pulley,

 

The pump was making a lot of noise after spring start up. I can figure a slight build up of rust on the drum may cause grinding sound and the fins also scrap. Bearings looked good. I'm not aware of any routine maintenance for the pump, what I did seems to work so far.

In a moment of indecision, I was tossing around a cardone rebuilt unit and then regained sanity I will never never ever as in never ever get anything rebuilt I don't care what it is. The cardone unit comes with a note that says it will be noisy for 500 miles. no thanks. And also considered the eliminator pulley which looks like a hack job which it is lets be honest but it works and cleans up the bay I know, and decided to keep the charm of the stock L98 air pump and bracket and try to make the best of it. At least I have something that resembles a smog device.