# Alternator problem??



## noiseordinance (May 30, 2008)

Hi there. I have a 1997 Nissan Sentra. I inherited it from my sister about 2 years. She JUST had the alternator replaced, and then someone broke in and decided she was done with the car's upkeep since she didn't wanna fix the window after shelling out money on the alternator. Anyways, that's just a tidbit of background on the condition of my alternator.

I was driving two days ago and almost ran out of gas (the fuel meter dropped a hair below empty, which I didn't notice since I was in a debate with my girlfriend). Anyways, my check engine light kicked on. I filled my car with gas, which of course did not turn the light off (I didn't think it would, naturally). However, this afternoon, while I was driving my battery and brake light started blinked erratically, and eventually, went on solid. I went to a car parts store and they ran the diagnostic device on it which reported a defective EGR valve. On my way home from the store, my airbag light started blinking. My wipers start moving very slowly (gotta love the Oregon rain). And then my speedometer start failing as well as my headlights, which was really fun since it's currently dark out.

I parked my car. I won't start back up. My battery is fairly old, which likely needs to be changed, but I'm guess it's not related to this mess. Is this an alternator issue? Could the failing alternator cause an EGR valve error? If it is an alternator, is this a fairly easy part to replace on my Sentra? I've done it on a Chevy truck, but of course everything is easy on a Chevy truck...

Any advice would be incredibly helpful, as I need to be able to work and get to school for finals this week...

Thank you a million, in advance...


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## akexnads (Oct 14, 2007)

easiest way to check is to get it started (borrow a battery if you need to) and remove a battery terminal, if the car keeps running alternator is fine, if it dies, you need a new alternator.


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## noiseordinance (May 30, 2008)

I'm not too mechanically savvy, so if I suggest something false, please forgive me. Doesn't the battery _only_ start the car and power accessories when the car is turned off? If my electronics are failing when the car is already running, wouldn't that mean something other than the battery? I recall once that an old truck of mine wouldn't start (I killed the battery) and we had another car with a failed transmission, so I took the battery from the car with the failed transmission, started my truck with it, while the engine was running, disconnected the battery and put my dead battery back in to charge it. This means that my truck was literally running for about 30 seconds without a battery even attached.

The above process was probably dangerous but I couldn't get either dead car close enough to use jumper cables.

Anyways, maybe it worked for my truck since it was an older car? Is there a real possibility that my electronic devices were failing while driving due to the battery? If that's so, I'll certainly change out the battery at least to test it....

Thanks so much!

PS - For what it's worth, while my electronic components were dying while driving, my actual driveability seemed just fine...


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## akexnads (Oct 14, 2007)

Your battery will power your car whenever the alternator can not, so if the alternator dies your car will run off the battery until the battery dies.


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## noiseordinance (May 30, 2008)

I totally get what your saying. So if the alternator can't power my car, which is what it seems like it's doing, is my problem most likely the alternator? Or is there a way that the problem I've described can be attributed entirely to a bad battery?


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## akexnads (Oct 14, 2007)

most likely, but you can try the test i mentioned in the first post to be sure


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## IanH (Feb 11, 2003)

if the battery and brake light come on together its almost certainly the alternator.....
The SE-R did exactly the same when alt failed....


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## maroonsentra (Mar 3, 2007)

akexnads said:


> easiest way to check is to get it started (borrow a battery if you need to) and remove a battery terminal, if the car keeps running alternator is fine, if it dies, you need a new alternator.


There is an easier way. Pull the battery and bring it down to Advance Auto. They will test it and better yet charge it at the same time. If battery is good, take it back put it in your car and it should start fine, even if the alternator is bad. Drive it down to Advance (if you're not far) and have them run a test on the alternator. You should then have your answer.


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## noiseordinance (May 30, 2008)

So I'm faced with a predicament here. I talked to my mom, who was the original car owner. She had the alternator replaced 3 years ago. Then my sister inherited in and had the alternator replaced 2 years ago. From what it sounds like, I will be forced to replace the alternator myself; third time in 3 years. Should I even replace it or should I drive this thing off a cliff?

I will certainly have the battery charged and tested. I will also re-install the battery and drive this puppy to the auto store to test my alternator. But I'm a little confused why this thing needs frequent replacement. Additionally, I'm not sure if I can even replace the alternator myself? I have a fairly basic set of tools, but I'm not sure how accessible this thing is or how difficult with belts and all...

Argh...


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## IanH (Feb 11, 2003)

Well unfortunately the re-built alternators don't have the same reliability as the OEM, but they are less than half the price.
My GXE still had the original when sold 11 yrs + later.
The SE-R had one re-built about 4 yrs ago. One in 11 + yrs.
So.... dig out the receipts, a lot of the auto parts store re-built's come with a lifetime warranty.
If you didn't get a lifetime warranty learn from your mistake OR buy one from your local wrecker yard for about $40 with 30 exchange.

As far as replacement, its fairly easy.
Move the coolant jug by pulling upwards.
The Alt belt tensioner is ok to get at, and then remove alt.
The idler has a center bolt to loosen plus the tension adj bolt.
If you have to remove the top coolant hose.


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## noiseordinance (May 30, 2008)

So this is something I can do with a mere socket set?


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## maroonsentra (Mar 3, 2007)

noiseordinance said:


> So this is something I can do with a mere socket set?


yes. That's all you need. Even though air tools speed the process up, you'll be fine.


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## IanH (Feb 11, 2003)

the other option is to diagnose the problem, take it apart and just fix whats wrong if its simple, if not buy the re-built with the core.
This is good because you only replace the part that failed, the resulting part last a long time compared to a bad re-built.
I have seen worn out brushes, Bad Diode trio, Bad power diode stack, voltage regulator (have take data with car running) and once a messed up commutator. All were fixed except the commutator,i cored that one out.


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## Chondra (Dec 10, 2008)

Before you go and rip out your alternator, check the slack of your belts and make sure the tensioner is on tight... My tensioner and serp belt flew off when I was on the hwy yesterday, then the brake/batt lights came on solid- maybe your car is sending out a warning that the same is about to happen to you...


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## maroonsentra (Mar 3, 2007)

Chondra said:


> Before you go and rip out your alternator, check the slack of your belts and make sure the tensioner is on tight... My tensioner and serp belt flew off when I was on the hwy yesterday, then the brake/batt lights came on solid- maybe your car is sending out a warning that the same is about to happen to you...


This would be kind of true, but the car wouuld totally overheat if the belts were this loose.


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## maroonsentra (Mar 3, 2007)

IanH said:


> the other option is to diagnose the problem, take it apart and just fix whats wrong if its simple, if not buy the re-built with the core.
> This is good because you only replace the part that failed, the resulting part last a long time compared to a bad re-built.
> I have seen worn out brushes, Bad Diode trio, Bad power diode stack, voltage regulator (have take data with car running) and once a messed up commutator. All were fixed except the commutator,i cored that one out.


I've actaully never knew you could do this. Seem very time consuming too. I've always got one from a yard, or a new one from advance. Always has worked for me.


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## IanH (Feb 11, 2003)

The water pump is on a different belt.
worth checking but i doubt its the belts.


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## maroonsentra (Mar 3, 2007)

IanH said:


> The water pump is on a different belt.
> worth checking but i doubt its the belts.


True. I was going on the fact someone said the "belts". I agree. very doubtful to be the belts. Check the amp's it's putting out to get a definate answer.


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## IanH (Feb 11, 2003)

maroonsentra said:


> I've actually never knew you could do this. Seem very time consuming too. I've always got one from a yard, or a new one from advance. Always has worked for me.


its not as time consuming as you would think. And I have not had to do this for a long time, newer Japanese cars !!!
when i was doing this it was the cheapest way to fix the problems, and I had 3 GM cars at the same time.
It seemed like something was wrong every month !!!
Brushes are very cheap, diode trio was cheap, voltage regulator was only about $12 at the time.


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## maroonsentra (Mar 3, 2007)

IanH said:


> its not as time consuming as you would think. And I have not had to do this for a long time, newer Japanese cars !!!
> when i was doing this it was the cheapest way to fix the problems, and I had 3 GM cars at the same time.
> It seemed like something was wrong every month !!!
> Brushes are very cheap, diode trio was cheap, voltage regulator was only about $12 at the time.


I know you mean, I had a jetta that was a nickel and time you to death car. Does advance carry all the parts?


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## IanH (Feb 11, 2003)

going by my experience you have to go to auto electrical supply or Japanese specialist.
These items are all readily available to the re-builders, its just a matter of finding who has them or will sell to you.
A bit like buying bearings from bearing supply house instead of the dealer but easier.


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## maroonsentra (Mar 3, 2007)

IanH said:


> going by my experience you have to go to auto electrical supply or Japanese specialist.
> These items are all readily available to the re-builders, its just a matter of finding who has them or will sell to you.
> A bit like buying bearings from bearing supply house instead of the dealer but easier.


I've done this with starters but always bought the parts at advance. Thanks for the tip.


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## Chondra (Dec 10, 2008)

maroonsentra said:


> This would be kind of true, but the car wouuld totally overheat if the belts were this loose.


My car didn't overheat even when the belt came totally off. And honestly, I don't see how that even makes sense...


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## maroonsentra (Mar 3, 2007)

Chondra said:


> My car didn't overheat even when the belt came totally off. And honestly, I don't see how that even makes sense...


There are TWO belts. IF the belt that came off or was loose on the water pump side, then the pump wouldn't be able to turn, causing overheating. This is the belt that usually gets loose in my experience. Can't imagine a belt being your problem. You need to get it tested, very easy fix. If the belts are tight, you're good.


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