Alternator / Belts Going Bad?

[douglasmiami]

I am having problem noises with my '99 RX 300. In the morning, with the AC off, I almost always have 15 minutes of high-pitched chirping/whirring sound coming from engine. I asked my dad if he though it was the belts, which I had read about here in these forums, but he thought it sound like bearings in the alternator. He didn't think that the belts, as they are made today (with the grooves), had as much slippage potential.

Obviously at ~$250 for a rebuilt alternator, I don't want to replace if I don't have to. Any suggestions?

[dgorrie]

I would think the first thing to do is determine for sure what item is bad. If it's the alternator bearings, try looking up alternator/generator repair shops and see what they would charge to replace them. I had a Porsche 944 (for 20 years!!) that had bad alternator bearings at one end, and a local shop (Plano, TX) replaced the bearing for $25. Of course, for that price, I carried it in.

Years later, a different generator repair shop rebuilt the alternator on the same car for about $150. Worked fine until I sold it.

To check the belts for tightness, you can reach down from the top (engine off, of course) and press on the belts. If they have only minimal flex in the middle between the pulleys, they are probably not the cause. Top belt is easy to reach – bottom belt is harder but you can probably use a broomstick or whatever.

I think the alternator is the topmost device being driven by the belts, nearest the front of the car. The power steering is on the bottom near the rear, and A/C compressor is below the alternator (if I recall – car isn’t here right now). If you are careful, you might be able to tell if it’s the alternator by holding a cheap stethoscope of similar device at each end of the alternator to localize the noise, while the car is running. But, just be careful.

FYI – if it’s the belts, O’Reilly and AutoZone should have them. I actually replaced mine a week ago at 90,000 miles, although they were actually still OK. It wasn’t bad, but a couple of the bolts that need loosening are a little hard to get to, and it helps to get instructions first. If you are handy and have metric tools, it can be done. I believe I used 10mm, 12mm and 14mm at different points.

I hope that helps.

[douglasmiami]

Dgorrie - thanks for the response. With that Porsche alternator, how did you know it was the bearings that were bad in the first place? Do you remember it making this high-pitched chirp?

Funny thing is, it doesn't happen everyday, like this morning, I started the car and had no sounds - quiet as ever. But tomorrow, I'll probably hear it. And it rarely makes noise when I start in afternoon on my way home. Only in the morning.

[RX in NC]

If your belts are the original factory-installed ones, you have a 95% chance that your belts are your problem. Particularly since you only hear the sounds occasionally. Change your belts and I'm willing to bet that you will have fixed your problem. I changed our AC/Alternator belt a couple of months ago and the vehicle is quiet again now.

Your belts may only squeal in the morning because they are still wet with condensation if you park your vehicle outside.

[alsalih]

This sound is neither the belts nor the alternator. This is typcial drive belt idler and tensioner pulley bearings. If you remove the drive belt and turn the pulley by hand you will clearly feel it being unsmooth and a bit loose when turning.

[RX in NC]

That might make sense if the RX300 had an automatic belt tensioner device. However, it doesn't. Again - change your original belts and your noise problem should be resolved.

[alsalih]

That's correct it doesn't have an automatic tensioner but it does have a tensioner pulley which is manually adjusted and the bearing on this pulley will wear and make the noted noise.

[alsalih]

Sorry I got this car confused with my Maxima, RX in NC is correct this vehicle does not have any idler or tensioner pulleys. Regardless though, I still think that you have a bearing noise. It's very likly the A/C pulley but just to be sure, spray the belts with a silicon spray and see if the noise goes away.

[douglasmiami]

Guys - thanks for the information. This belt spray - I assume I can get this at Pep Boys. What exactly does it do? Or what would it prove?

[ghong001]

Use fan belt dressing not silicone spray.

I had the same problem with you and it turned out to be the belts.

Mine sounded really bad and I initially thought it was the alt bearing also.

Do a search on belts on the forum and you will see that it is a very common problem.

George

[ghong001]

BTW to answer you question, the belt dressing and silicone spray will do the same thing which is to soften up the belt as the noise usually comes from a belt that has dried out and gotten hard and non-pliable. Belt dressing is better as silicone can make the belt slip as it has lubricating properties.

[RX in NC]

I don't know how much plainer I can say it - your belts are long past their lifespan (typically three to four years regardless of mileage), so change them. You can dress your belts from now until doomsday but you are simply postponing belt breakdown which will strand you wherever it happens. Change your belts and go back to getting some peace of mind.

[ghong001]

In other words.....

Use the belt dressing to determine if the problem is your belts.

If the noise goes away once you use the belt dressing then the problem is in your belts.

Change them and be done with it.