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Discussion Starter #1
For the last week or so i thought i had alternator whine. Read up on it, was gonna take a long hard look at the alternator this weekend. I have a volt guage installed so i've been keeping an eye on things, no strange power loss, constant 12.4 volts with engine off, 14.4v when driving, only A/C turning on and heavy bass hits would make the needle budge(engine on, standing still).

But new developments today ...

turning on the a/c doesnt always work, doesnt kick on and the guage stays right at 14.4v with engine running and car at a standstill.

the a/c will randomly turn on and off when on and the volts never really recover to 14.4volts ... just kind of hover around 13.5volts.

all the while the car makes the alternator whining noise, like a small supercharger.

any suggestions on what the issue might be?
 

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You may wish to double check your gauge with a volt meter. 14.4 volts sounds high. Should be more like 13.8 with a fully charged battery.
AC problem could be a bad relay.
 

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Discussion Starter #3
yea the guage is a basic mitsubishi guage. any idea on the whining sound? could a bad a'c compressor make that sound instead of the alternator?
 

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Yes it could be the AC compressor. You need to run the car with the AC on and off. Each time stick your head under the hood and see if the noise is coming from the AC unit or the alternator. You should be able to pinpoint it.

A range of 13.5 - 14.0 volts would be a normal range for the alternator to charge at.
 

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Discussion Starter #5
Thanks. I'm gonna try that tomorrow. Im also gonna take the car to autozone for them to test the alternator. Can they detect if its getting weak? Or only if its dead?
 

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They should be able to test it and tell you if it is weak. What happens is either the wire coils inside the armature get shorted, or one or more diodes become open. I think you will find that the alternator is electrically OK. However, that doesn't mean that the bearings are good. They could be making the noise also. If the alternator bearings turn out to be bad, then you should replace the alternator because it will fail relatively soon.
 

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Discussion Starter #7
thanks for all the info man. really appreciate your quick responses. i will update tomorrow
 

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Discussion Starter #8
yea they tested the alternator and said it was running fine. they also suggested that the bearings might be bad, jst like mentioned above.

i'm on the hunt for a b15 alternator as they are supposed to be a direct replacement and put out a few more amps.

any thoughts on the A/c sytem problem?
 

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AC systems are designed to shut off if the pressure in the system is too low. You may have a leak in the system. I would take it to an AC shop and have them check the system pressure and diagnose the problem for you.
I don't think the alternator and AC problems are connected, unless it is the AC unit making all the noise.
 

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Discussion Starter #10
the a/c problem obviously isnt as important to me as a possibly bad alternator, especially with winter around the corner. can a bad bearing on the a/c compressor lead to any more serious damage?
 

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I'm going thru a similar prob.- something on the front of the motor making a rough bearing sound. Nissan mechanic thought it might be the water pump. I'd bought one of those stethoscopes at AZ, hadn't used it yet. Using it, took me about 3 minutes to figure out it was clearly the power steering pump. The 'scope is very inexpensive and seems ideal for diag bearing problems.
 

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Discussion Starter #13
Actually the belts were last looked at about 50k miles ago, sad to admit. I'm gonna have to change them out anyway, but im considering UR pulleys once i start pulling stuff apart.

where can i get that stethoscope? what is AZ?
 

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ChickenWing said:
Actually the belts were last looked at about 50k miles ago, sad to admit. I'm gonna have to change them out anyway, but im considering UR pulleys once i start pulling stuff apart.

where can i get that stethoscope?
I think belts are scheduled for replacement around 60K... so youre close ;)

I really think they may be too tight. Try loosening them a few turns and see if the whining goes away. I have some very lightly used belts (NAPA Gates) for the UR 2 pulley set you can have for $15 shipped.

I think I got my stethoscope at Harbor Freight for about $10. After using it, I thought my gf's RAV4 had a bad belt tensioner... I replaced the belt and the weird tapping sound went away. Seriously, belts are cheap and can make a lot of strange noises.


- Greg -
 

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Discussion Starter #15
Thanks for the heads up. :) Is it really possible for belts to become tighter then they were 50k miles ago?
 

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AZ=Autozone

No, belts will get loose with age and miles. If this is a recent new noise, then most likely something is failing. Could be any device turned by the belt, including the belt tensioner and possibly the belt itself.
The use of the mechanics stethescope is a good idea. Sometimes a long screw driver with the tip held against the suspected device and the handle end up against your ear will work like a stethescope.
You just need to get a good close listen.
 

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Discussion Starter #17
A little update. At this point i should be handing over my keys to some random 4 yr old. At lunch i go out to my car and the keyless remote doesnt work ... weird but i unlock manually and start it. Radio(Alpine) is off(its supposed to come on automatically if thats how it was left) ... weird but ok. Look at my odometer ... set to total miles, i left it on trip1, which has been cleared along with trip2. Amp on sub is de-tuned.

Lost power. Why? The (+) battery cable was loose. I thought that mighta been it especially after having my alternator tested.

Result: Well unfortunately the noise is still there. :( But it does idle smoother!

I'm an idiot, and the journey to the sound continues.
 
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