If I were you, I'd just buy another Meziere or CSI pump. They do a way better job at keeping things cool than the stock pump does and they're easier to replace (after they're installed the first time, that is).

Diagnosing it will be easy...just put 12v to it and see if it makes noise.

 

That is exactly the way I am looking at it at the moment. The GM pump is about $194 plus shipping and the replacement Meziere pump is about $261 plus shipping from Summit. Heck, I'd pay $70 to be less pissed off any day.

I plan to try to diagnose over the weekend.

 

Jesus christ, that's way more expensive than a CSI. Here's a Meziere on Jegs for cheaper. I think the one you saw on Summit is a heavy duty model...not really needed. The standard one in that link should do you fine (and save you $40).

 

Yes, the standard model is also at Summit. I run this car on road race courses from time to time. I figured I'd get the higher-flow model since that is what is in there and even with the oversized rad in there, it still runs warm on hot days.

Jegs and Summit's pricing is about the same. The only bonus for me is that Summit is a couple of hours up the road and across state lines so I usually get the stuff the next day.

...hmmm, maybe it's Jeg's turn to get to play with my credit card number... I didn't notice, are either of these guys sponsors here?

 

I just got my 5 minutes to check the car out. The noise is not coming from the water pump. It sounded like the A/C compressor but I checked the pressure as a starting point and that was fine. Then for the heck of it, I sprayed the belt with some belt conditioner and the noise got worse? Weird. I waited and sprayed some more and the noise went away. Working theory is that the belt is not liking the cooler temperatures.

I have a spare belt and will change it when I get a chance. It appears that today is one of my wife's "lets shop all day" days so when she comes back and can watch the kids, I can go change the belt. Maybe tomorrow...

 

I just changed the belt. I had the noise before and I don't have the noise anymore. Since the noise wasn't constant and varied from nothing to loud enough to hear in the car, I won't call it fixed yet but it probably is. Thanks for the input.

Just some data - I contacted the previous owner and he told me that with the aftermarket rad in there, I have to stick with the standard-duty pump. I checked and saw that the standard duty pump is 3" and the heavy duty pump is 3.5". I guess the clearance is such that this half-inch is important. This also explains why he rigged up the booster for the pump that is in there.