2003 Buick Century Belt Noise After Replacement

Last week I had the serpentine belt replaced in my 2003 Century, V-6 3.1, and soon after that it started to squeal loudly when car is started. The squealing stopped shortly after running. My instincts told me that the belt was not tight enough but the people who installed it checked it out and said it was ok.

Do you think I need to replace the idler pulley, the tensioner pulley, or the power steering pulley, or all of them? I noticed a noise coming from what seems to be the power steering pump but the fluid level is good. This Century has over 150,00 miles on it and it’s in great shape.

Assuming it’s one of the problems listed, how do I tell if I need to replace the power steering pump, the other serpentine pulleys, or whether or not I’m even in the right diagnostic realm? Any thoughts?

Yes, the belt has no adjustment, so it would not be loose, unless the tensioner was bad. Usually they will look a little cockeyed because the inside where the spring is has worn out. But the pulley on it could also be making the noise.

Any one of those parts could be causing your noise. The power steering would do it all the time.  A noisy air conditioning compressor would change the sound as you turn it on and off. The best way to determine which one is bad is to use a stethoscope on the component while the engine is running. Or you can use a long screwdriver with your ear on the other end and touching in part. Be very careful not to get it into the belt or any moving parts.

I would also spray some brake cleaner on the belt to clean off any fluid that may be on it. Oil or coolant leaking onto a belt will make it squeal. A little grease or belt dressing may also help if the belt is what is making the squeal noise. If this does fix it, drive the car around to make sure it is gone. If it returns then start checking the power steering pump, idler, water pump or A/C compressor.
Question: How can I tell if an idler pulley needs to be replaced or if the entire belt tensioner assembly needs to be replaced?

Answer:A bad idler pulley will usually be noisy when it needs to be replaced. The pulley may also wobble. If the complete tensioner assembly is bad, the arm would be loose or not straight or will bounce around. Some vehicle / engines you cannot just replace the pulley, you must replace the entire belt tensioner. It all depends on make, model, year and engine size.