Join Date: Oct 2015
I'd probably take off the serpentine belt and spin the water pump, alternator, a/c and idler by hand, maybe it will be obvious which one is the culprit? You could also start the car just for a minute and see if the noise is gone, that way you'd if one of them is responsible. I've had a noisy water pump on a honda, oiled it and it would last about 30-40k before needing another squirt of oil to silence it, had the car for over 100k and never needed to replace a part on the engine besides plugs and filters. I did have a noisy alternator on a ford once, that needed a new alternator by the end of the week, it was too far gone.