I'm trying to diagnose a noise I've been getting from the serpentine belt area of my car for the past month. It started suddenly, but hasn't gotten worse.
When it started, I noticed some residue around the waterpump and evidence of spray on the inside of the hood. A pressure test confirms a leaking water pump. I replaced it. The noise doesn't go away. Reading online, I learn that the belt tensioner tends to go out at about this time (115k miles). The shop confirms it's bad and it's replaced. Noise gets better, but doesn't go away. The shop thinks it is the alternator (guy said he used a stethoscope to trace the sound to the alternator). I pulled the serpentine belt to check the alternator myself. There is no play in the shaft that I can discern. It rotates smoothly, but I can just barely hear a faint noise, almost a scraping sound, when I rotate the alternator. I can't feel it through the pulley though. With the car running, the noise is intermittent. It might make the noise for a bit, the stop, only to start later. Sometimes it starts when I crank the car and quits later, other times, it'll not make the noise until the car is warmed up.
What could this be? I've already spent $750 on this sound. I'd rather not replace the alternator if it's not bad.
If the alternator is going bad, but still charging, when does it become critical?
The car is a 2003 Toyota Camry 4cyl with 115k miles.
Chris
Here's what I beleive to have happened...
The water pump started leaking. The serpentine belt carried the coolant (and sediment, and rust, and stop-leak - you get the idea...) along its path, where it, and the dirt it picked up off of the belt were drawn into the front of the alternator by the alternator pulley cooling fan, and into what would normally be a sealed front bearing, but which has obviously worn to the point that the grease can wash out, and dirt and water wash in, You now have dirty, rusty ball bearings - sometimes they pick up what's left of the orginal grease from the sealed bearing and quiet down - sometimes they run dry and noisey. The bearing will eventually fail. Good nes is this a cheap and easy fix - if the alternator is otherwise charging ok. You just need a front and back bearing, and a set of brushes for your alternator - (spend the money and get them already assembled in the bush holder with the springs and a lock strip, especially if this is your fist time. The old brushes will pop out of their holder when you pull the two halves of the alternator apart ( BIG TIP/HINT: take crayon or marker and draw a mark across both halves so that you reassemble them correctly.) The new bushes/holser will have a plastic straw that will poke out of the back of the alternator whne you bolt them in: don;t pull this straw until the alternator is completely reassembled, with both halves oriented correctly - otherwise, you will have to completely remove the brushes and holder, push the brushes down against the springs, and put the little lock strip back in theough the holes. (When you just replace brushes, you re-assemble with the old holder and springs, and use a piece of wire or the straw off of a WD-40 can....) The back bearing is usually a cup/needle bearing, like in a U-joint - drive out the old one with an appropriate sized drift (or socket, if you a po boy...)
and gently tap ini the new one. Front bearings are normally hels inplace with some kind of bolts - you'll figure it out. If you can only get brushes, see if your town has a "Bearing supply" store - take the ld ones in, and they can cross-match the numbers. Very cheap, & your alty will be ready for another 100000 miles. If you have a starter and alternator shop, you can pay them to do it....
