alternater on the blink??

[mmx005]

Hi guys,

So I think my alternater is on the blink, here's why I think this

Was returning from the city to gosford on Sunday and while sitting at the lights waiting for a green, my charge light (battery symbol) come on. After driving away from lights charge symbol went out. Checked the battery when I got home13.1V.

Run the car at idle from cold on Monday for 25min nothing. Got 13.8V to 15.1V when fully loaded up with high beams, foggies, a/c etc. No charge symbol come on while running.

Wednesday (tonight) went for a gentle 20min cruise to a matyes and charge symbol comes on, I was getting 11.7V on the multimeter at idle. Turned car off, got 12.8V. Started the car charge symbol stayed on drove down the road, got to 3000rpm and the the symbol went out and not seen again.

Have checked belt as it Was changed last month, seems fine, not loose.probably a little fiirm if anything.

Suggestions ladies and gentlemen???

P.s car contains a moded 98 nb8a engine with lumpy arse cams and an idle between 900-1200rpm

Thanks in advance,

Ben

[93_Clubman]

If it's the alternator, tapping the alternator body when the battery light is on might also make the light go off.

[greenMachine]

If it is the NB8A alternator, be aware that it is regulated by the ecu. AFAIK, all other NA/NB have internal (to the alternator) regulators.

If you need to replace it be sure that whoever does the job knows the difference.

[mmx005]

not sure about you guys, but im really not a fan of reaching into a running engine bay.

i will be doing the change if it is shot. will be removing the old one and taking all the part numbers off it befor ordering a replacement.

thanks guys

[93_Clubman]

not sure about you guys, but im really not a fan of reaching into a running engine bay.

Broom handle or similar if you have to.

[Russellb]

Hi Ben

Are you running the NB8A Alternator ???
Or are you using the NA8/6 Alternator ???

Need to Know so I can Help

But From What you describe it sounds like one OR maybe two of the Phases of the Alt have DIED
more than likely the one that excites the magnetic field of the alternator.

Or it could be a blown Fuse/ broken wire to the exciter side of the ALT

Check that then is batery voltage on One of the pins in the 2 pin plug ( i forget which pin )
one pin controls the light the other is to excite the magnetic field

using a test light test between the two pin plug of the ALT and ground
with the IGN on one will glow dim and the ALT light will glow dim
the other will glow BRIGHT and now glow from the ALT light
if this test has these results the the ALT is DEAD

[mmx005]

i have an NB8A running adaptronic ecu and modded engine

thanks for the heads up, will try your test b4 i rip the alt out.

cheers :-)

[Russellb]

i have an NB8A running adaptronic ecu and modded engine

thanks for the heads up, will try your test b4 i rip the alt out.

cheers :-)

Forget those test i told you about , they dont work with the NB8A ALT
time for a new or second hand one.

[slimx]

im not too familiar with the issues but look
When i bought my car

myn use to go off and on .. as if something was loose i use to check it all the time.

I checked the battery it was at normal volts this that.. I went to a auto electrician they told me my alternator was out. over charging... blah blah
I got pissed off because i knew nothing was wrong with it. I was ujst soo sure..
I left it

I convinced myself that one day if it blows ill change it its only like $100 anyway.

One day i went to mx5mania.
One of the workers drove my car and asked me if i wanted to fix that light.

My air temperature sensor was replaced. And bang it DISSAPEARED!! forever
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Wouldnt hurt to try i paid $15 for myn