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trypaw's avatar

Is my Alternator/Alternator Bearings going out? Strange noise when accelertaing?

Asked by trypaw (327 points ) July 26th, 2012

I think I finally found out whats wrong with my car. Whenever I accelerate there is a vibration from the gas pedal and almost like a groan, or vvvrrrrrrrrrrrrrrrr sound. Its gotten alot worse in 3 days, It was barley noticeable at first, and it used to only do it at low speeds. Now it does it all the time. Anyway. I popped my hood and had someone rev my engine up to 3 rpm the sound sounds like its coming from my alternator makes a whine/groan. Is it possible its dying? Or my bearings are bad? Nothing else is weird with my car, every electrical works, car starts fine. Just this sound coming from my alternator. Should it make this sound? And would it make this sound from my alternator if my belts weren’t properly tightened? (hoping its not the alternator) I had someone look at it and that’s what they told me was bad, but I’m not so sure being as everything else with the car is fine.

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22 Answers

Crashsequence2012's avatar

It’s entirely possible that improper tension (Overtightening in this case) could shred the bearings in your alternator.

tedd's avatar

Generally if it’s making noise like that, something is wrong with it. Specifically what and specifically the cause would require a further look at the car. As @Crashsequence2012 it could be as simple as the tension/belt. Or it could just be an old alternator.

Judging by most of your recent posts my semi-professional opinion is that you need a new car, lol.

Tropical_Willie's avatar

Check belts first, bearings usually “sing” at all speeds, only during acceleration could mean slippage. And yes @Crashsequence2012 a too tight belt may wear the bearings. A rebuilt alternator could cost $200 or more, no labor.

trypaw's avatar

So would you say that when I had that mechanic work on my car, they could have tightened my belts too much and caused my alternator to go out? Because they told me that my alternator was probably already bad and that when they put on new belts nice and tight, my alternator sound is more noticeable, instead of driving with my old belt I just couldn’t hear it? Because they swear to me they didn’t break my alternator but its weird it wasn’t doing this before they touched my car/belt.

trypaw's avatar

@Tropical_Willie what do you mean by slippage? As in my belts are slipping?

trypaw's avatar

And no I don’t need a new car. I got screwed over by Zues auto here in my town and they broke my car. I have had this car for 4 years without a single problem until they touched my car. I have a new alternator if I put it in I will have to take off my belts right?

tedd's avatar

@trypaw I doubt they could’ve put the alternator in (or any other parts) in such a fashion that would have made it go bad. If your old belt was old, it was worn out and stretched, meaning it had less tension than a brand new one did. When they put the brand new one on, the original tension would return, and it would be much more noticeable.

You said that you only noticed it at low RPM’s before, was that during your entire drive, or just after initially turning the car on? Was it worse when it was cold outside? When you first turn the car on your belt is tighter. As you drive it heats up and “loosens”, weakening the tension. This is especially common in older belts, and very common during the winter (the cold weather causes it to have more tension).

What year is the car again, and is it the original alternator (mileage would help too) ?

trypaw's avatar

@tedd Yes, during my entire drive it only used to groan as I “accelerated from a stop” (Monday) now it does it basically every time I accelerate. It has to do with the pressure I have to put on my gas pedal. Once I hit that spot it roars. It is less noticeable while driving but still there. It is still mostly heard while I take off from a stop. Also Its been hot here all the time we haven’t had any cold weather.

98 Dodge Startus 149 miles I believe this is the original alternator. My parents owned this car previously since 01 and never replaced it.

Crashsequence2012's avatar

There is a quite precise proper tension for the belts in your car.

The alternator may be old and the noise may be due to worn bearings but if it’s working, it’s working.

An improperly tight belt could certainly make the bad bearing situation worse, bringing the alternator to the end of it’s life sooner than necessary.

I would find a reputable shop to inspect and properly tension all the external belts This could give you more time before alternator replacement becomes essential.

Edit: I think I see above that you have a replacement alternator. If you install it yourself the belt will come off on it’s own when you loosen the unit. Again I’d have a shop check the tension soon after you put it in. This also gives the tech a chance to look at your work in general and is less expensive than having the shop do the complete install.

tedd's avatar

My assumption without looking at it, is simply that the alternator has gone/is going bad. I doubt anything the auto guys could’ve done would’ve really accelerated that or damaged it, short of straight out damaging it in some manner. But via neglect, I doubt they could’ve done anything to it.

It is worth doing what @Crashsequence2012 said and ensuring the tension is right. But getting the tension right on a belt is elementary. If any mechanic messed that up I have to question how they dress themselves in the morning. If you have an auto-knowledgeable friend I suspect they could check it for you without too much trouble, but a shop would work too.

At the root though, it does sound like your alternator is just on it’s way out.

trypaw's avatar

@tedd Thanks for your help, my friend is coming over hopefully tonight to put on my new alternator. I just spent 200$ on it and just wanted to make sure Zues is right. Once I install the new alternator I cant take it back if it doesn’t work :/ But I’m glad to know that its probably my alternator. Ill have my friend check the tension too before.

tedd's avatar

@trypaw Oh I didn’t realize you already had one. Yah I would do that first then, lol. Definitely the easiest way to check. If it still makes the noise, first ensure it’s coming from the (new) alternator (it could be the belt itself if they used the wrong one or it’s over-tensioned or something)... and go from there, either confronting Zues on their crappy job, or being happy with a working alternator.

trypaw's avatar

@tedd Took out the alternator checked it. It was still good. So put the old one back in. Re torqued the belt that goes around it and now, it seems way better sounding. It is still there very slightly. But I mean it sounds WAY better than it did. So I’m thinking the belt was too tight. I think we got it a little less tight but my friend didn’t know exactly what to torque it to so its just there still a little. I’m taking my car in on Tues anyway and they can check the belts. But does that sound promising? After taking off the alternator and just putting it back on and re fitting that belt it sounds so much better,. Its just barley there. Also if it is the belt and now it sounds better is it ok to still drive my car short distance?

tedd's avatar

You should be ok driving your car even if the alternator is going bad. In my experience the worst case scenario is it goes out and your car dies from power loss. It doesn’t really do major damage to the engine or anything, and as soon as you replace the alternator you’re back in business. Just be conscious of the fact it could die on you and don’t plan to take it on a 5 hour trip or do something super important without a back up plan.

That does sound promising if the sound went away, but it could just be you guys didn’t tighten it as much as it should have been. Did you try the new alternator out? Getting it checked out is definitely a good idea. I can give you all the advice you want, but at the core of it without popping the hood and looking at it myself, a lot of it is just intuition and experience.

Crashsequence2012's avatar

I’d say it’s safe to drive the car around town.

When the alternator goes a light will come on on the console indicating that the alternator is no longer topping off the charge on the battery.

The car will still be drivable for a short time. Any electrical things you can shut off will increase this time a little. Head straight for where you will have the alternator replaced. You might consider keeping the spare in your trunk.

I’m glad to know you have a friend that can do this work instead of Zue’s. I’d never go back there.

trypaw's avatar

Well like I said yesterday I was going to install the new alternator but I found out my original one (one in my car) is fine and its not broke. But after I took out the alternator and put it back in, the growl when accelerating is quieter overall compared to earlier. Now it just seems the growl is more prominent when the car is warm. I’m thinking my belts were too tight from Zues. I don’t think we put them on quite torqued enough either but Its making the sound less, and All we touched were the belt around the alternator and the alternator. Now just have to find out why.

Satchafunkilus's avatar

Try disconnecting your battery to see if your alternator is working. Unless it is a desiel vehicle, then that will not work.

Tropical_Willie's avatar

@Satchafunkilus The battery needs to stay connected to the alternator ( it charges by turning the rotor through a charged stator ) to make power.

Satchafunkilus's avatar

No… A vehicle will run with the battery disconnected if the alternator is working. Though, I might be wrong about newer cars that are so very computerized and has some kind of fail-safe preventing that. Not sure why it would.

Tropical_Willie's avatar

The stator has to to be excited or loaded with a DC current. Some will run, if they are self-excited for a short distance. The magnets in the stator are electromagnets and have to have a DC current running through the stator to make it a work. If you drive a car as the battery is dying it will stop running when the battery finally dies ( not true on diesels ).

Satchafunkilus's avatar

Hmm… what is a stator?

Tropical_Willie's avatar

STATOR IS THE
The band of iron around which the rotor is is moving.

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