Can a bad water pump make your car sound like garbage? The reasom im asking is because i had an 92 Bonnie and the water pump worked fine, no over heating or leak but the car sounded horrible. I changed it and it was as quiet as a whistle. Now the */C 3800 Riviera i have sounds like GARBAGE until it warms up then it quiets down. I was wondering could that be the problem, I dont wanna take it off because it seems harder to do than an regular 3800 because of the pully'* and belts. Any suggestions?

For a water pump to make a lot of noise like you are describing it would seem the bearings would be gone.

Either way I think it would need replacing soon. On your current situation try removing the belt and starting it for only a minute (no cooling). Might be harmonic balancer.

The balancer wouldn't quiet down after the car is warm. The only thing extra you'll have to deal with on the Series I L67 is one extra belt. That'* it. On an NA, you might want to remove the alternator, but you don't have to.

Maybe a belt tensioner bearing?

There is also the idler pulley