1991 Ford Explorer Chirping Noise

I just got my truck out of the shop, they put a new alternator in. When I started it, it sounded like there were a whole nest of birds chirping under my hood. I took it back and they said it must be the alternator (it was used). They said they replaced it (I don't think they did) and it was still chirping. Then a couple of days later, I blew a cylinder on my back wheel. When they had it up on the lifters, they said they sprayed some lube and found that the chirping noise was coming fom my water pump and it was going out. Could that be true or am I getting shafted? Because my truck never made that noise until it went in to the shop for the alternator. Thanks!