Pontiac Repair: Firebird screeching noise after start, pontiac firebird, water coolant

Question
I have an '02 Pontiac Firebird w/automatic transmission. As soon as I start the car, I hear a screeching (almost sounds like a cat dying) noise coming out of the driver side of the engine. The noise gets louder when I rev the engine but if I drive for a while, eventually the noise goes away. Took it to a mechanic and he replaced the alternator but that didn't do anything. He also said I needed a catalytic converter, so that may be it too. Also, may or not be related, my exhaust sounds horrible as if there was a loose component or something. So I'm just wondering if it really is the catalytic converter before I spend any more money and if the alternator had anything to do with it, or should I try to get my money back. Any help would be appreciated. Thanks :)

Answer
Hi
Lets start with the screeching.
The noise I believe will be a belt driven accessory. If it is coming from that side of engine, have ANOTHER mechanic check the power steering pump and the serp. belt. If they check out OK, have them check the ALIGNMENT of the belt driven accessories.Make sure all the pulleys are lined up.
Make sure there is no liquid getting on the belt (oil, water, coolant, power steering fluid, etc....) as these also will create noise.
Next the converter. If your vehicle is under 8 years old OR 80, 000 miles, you cane get the converter covered under your GM factory warranty. They are covered 8/80.
If not, go ahead and get the converters replaced. You will come out ALOT cheaper by getting "universal" converter at an exhaust shop, as opposed to a "direct fit" converter. Shop around if your out of warranty. Personally, I have never heard a converter screeching. I have been doing this A LONG time. I have heard them rattle and sound really bad, like yours. I can say it will not get better, o think about getting this repaired.
As far as getting $$$ back, I personally would give you your money back, if requested. I would though, first ask you as a customer, to allow me to fix your problem, labor free, parts at cost. Thats me. I would want your buisness to continue and your word of mouth to be on my shops side.
Thats me. What your mechanic will do or is willing to do I cannot say.
You can demand your money back. You can turn the shop into the BBB or local Chamber of Commerce.
If it makes same noise with new Alt on vehicle, I personally would not have even let it leave my shop. It'll be hard to get your money back, but I always say to try, and you never know. See if you and shop owner or service manager at shop can work something out.
Your word of mouth about this shop to your family/friends/coworkers is worth WAY more, in the long run to him, than the few hundred dollars he may have to refund you. Stress this point.
I first apologize for that shops mistakes.
I do hope this helps.
Just advice from experience.
Good Luck
Pawl