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Symptoms Of A Bad Alternator

Crans

By Crans,
in Engines & Forced Induction

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Crans Mentor

Crans

Posted
Posted

I am pretty sure my alternator is stuffed.

The start of the problem, apart from car generally running like crap.

Installed a new turbo, this took weeks due to excessive beer drinking while working and having custom intake pipes made, forgot to disconnect battery for some of this time so it went flat.

Jump started car. First attempt mate had + and - around the wrong way = epic fail and sparks.

Got car running apart from rough and lean idle and extreme lag all good.

I went away for a week in march and battery went flat again. Took it for a 10 minute drive. Parked for 10 minutes car had to be push started.

Then took it for a 1/2 hour drive and this was enough to charge the battery for the next start.

Next day battery is flat. Replaced battery. New battery went flat shortly after. charged and it hasn't gone flat since.

Now the big thing pointing me towards a stuffed alternator is the idle goes very rough and very lean when the lights are on.

Found this out going through maccas drive through(Never drive my car at night so first time i noticed his)

As a test on the way to work today i turned the stereo and all accessories off and the idle fueling was actually sitting quite normal around 14.7 - 15

So basically how do i test the alternator and is there any common R33 problems, like a bad earth or something like that before i go looking for a replacement.

Also consult showed idle voltage as around 12v dipping sometimes to 11.9v, really though this should be more like 13v - 13.5v

Also could the lack of power be causing a very laggy car? I was thinking not enough power to coil packs causing a weak burn?

What are the options on replacement? will a rb30/rb20 one fit?

Cheers for the help and sorry for the lengthy crap filled post.

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jrm Veteran

jrm

Posted
Posted

Voltage at idle should be anything from 13.5-14.4V, if you're only seeing 11.9V or so, there's definitely an issue with the alternator, and it's probably not adequately charging the battery either.

I'd be talking to an auto-elec and get them to check it out. I wouldn't be surprised when you had the connections back to front when jump-starting it fried something in the alternator.

Either way, shouldn't be too expensive to replace or recondition to fix it up.

Boosted Mayhem Rookie

Boosted Mayhem

Posted
Posted

One of two things could have probably happened.

One, you fried a fused link in the wiring (if Japanese cars have them). Or, you have fried the internals of the alternator itself due to having the jumper cables on the wrong posts.

Also, if your battery goes dead, it's best to charge it fully before starting it. Some alternators have issues with trying to fully recharge a battery and can cause them to go bad. Had this happen eons ago with my first car. Batt went dead, jumped it and left it running for a while to recharge it and ended up frying my alternator. Went through two alternators before I went to a shop that told me what was going on. (Damn GM cars of the 80's...lol)

Would be a good idea to get a new alternator and make sure the battery is fully charged. If you are still having issues after that, you probably have a constant power somewhere sapping your battery's juice. A good earthing kit would be a good idea too.

gelousi Collaborator

gelousi

Posted
Posted

Yeh check fuses in the bay you might have blown a fuse when connecting the polarity the wrong way around also get a multimeter test from earth anywere and to the posotive terminal on the back of the alternator, im pritty sure its a thick white wire coverd by a black gromet with a 12mm nut see if your getting power there if not then there is a break in the circut from that to the battery

Brezza Proficient

Brezza

Posted
Posted

mate,

sounds like its your fusable link.

on my GTR i put the terminals on the wrong way round because i used my brothers battery out of his car to start it. fried the fusable link. could tell because no lights or accessories would work, just the engine would run.

got an auto elec to fix, remade link. lasted about a year, then recently it was burning out slowly, prob because it wasnt a strong enough link for the replacement. the power steering was cutting out, then the guages didnt work, so i couldnt tell how fast i was going, it was really bad. then the battery went flat.

so what was happening the car ran the battery completely flat and the alternator couldnt charge because the link was broken.

get the link fixed, its only a cheap part, i think it was $50 from nissan.

and remember, next time 'Don't connect the battery the wrong way round'

good luck

Crans Mentor

Crans

Posted
  • Author
Posted

Wasn't me that connected the jumper leads ;) I can safely say i have never been that stupid.

New battery has been running fine for the last 3 months. So problem is low running voltage. Could this still be the fusable link?

Brezza Proficient

Brezza

Posted
Posted

yeah its a pretty stupid thing,

not sure whether it could still be the fusable link?

i am not a mechanic, was just telling you what my experience was with a similar issue.

prob need to check with a auto elec or someone with tools to check it with a multimeter or something?

Jaredo Explorer

Jaredo

Posted
Posted

I'd take the alternator to a auto sparky. Probably borked the regulator with the swapped post mishap. Pretty sure they can do load tests ect to find out the cause.

I've had a flat battery and roll started the car to get it going and it ran quite rough so yeah not enough power would be causing the rough idling you seeing.

lookingforboost Community Regular

lookingforboost

Posted
Posted

my sil played up like this for ages before i worked out what was going on, i put new terminals on new earth leads (thicker) and got the alternator rebuild it was something to do with the reg, then the car was so much better to drive smooth and even felt like it had more power!

  • 14 years later...
silviaz Experienced

silviaz

Posted
Posted
On 6/1/2010 at 11:16 PM, Rekin said:

I had a rough idle when I had lights on. Ended up replacing with a rebuilt alternator and good as new!

Did you find that your voltage of the battery wasn't where it's normally supposed to be? for example on my r34, it's at 14.5v when running after a few seconds, but I noticed when I had a rough start and it initially wasn't idling correctly, the voltage on my triple gauge cluster was showing lower than usual. Seems like the alternator is starting to crap itself

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