70 amp Alternator

[aye mate]

I got a new alternator from Napa today and its a 70amp whereas the stock is 80 amp.
I have a few questions: Would having a 70 amp alt. cause the battery light and parking brake light(bad alt.) to come on?
Also, I tested the voltage from the negative battery terminal to the alternator and it read 12.28. This is the same reading I got when I tested pos. to neg. battery terminals. What does this mean?
And finally, would it be ok to drive with the 70 amp alt? I have an MR2 100 amp alt on the way but I need to drive the car and the new alt won't be here until thursday.

 

[Sonex2000]

I was actually looking for that alternator today. I went RS Straus and asked for the MR2 alternator from an 89 and they say it is 70amps. What gives?

 

[jdub]

I was actually looking for that alternator today. I went RS Straus and asked for the MR2 alternator from an 89 and they say it is 70amps. What gives?

You need the '90-91, 2.0L Turbo w/ powersteering. This MR2 has electro/hydraulic powersteering, hence the need for a 100 Amp Alt.

 

[CPT Furious]

Wasn't there a way to take it to a local shop and have them add more windings and hence, more amperage...?

 

[shaeff]

captain, yes, there is. though, i dont have any shops capable of that near me that i know of...

-shaeff

 

[kewlcoconut]

i have been through 2 alternators myself. the stock one, and then a brand new stock replacement. lasted me 1yr because of my system. so i decided to get the biggest mother i could put in there. 120amp was the largest that would fit. and that took some cutting on the bracket holding it lol.

 

[Sonex2000]

I got a ringing sound from my alternator. It sounds like a bearing is loose. or something....i don't know.

 

[shaeff]

i've seen so many people replace their alternators, when all they actually need is to change out the brushes!

alternator $70+
brushes $5.99

-shaeff

 

[IJ.]

i've seen so many people replace their alternators, when all they actually need is to change out the brushes!

alternator $70+
brushes $5.99

-shaeff

Advice on SM Priceless

 

[Cravin Boost]

my exp with a BAD alt was those 3 lights comming on and staying on. I actually had issues with the windings in my old one and the dillrods at the shop were only replaceing the IC and calling it good in the end they hsd to go buy a fully rebuilt one to put on. serves the bastages right for tyring to cheat me!

 

[Supraholic]

where to get brushes???? any recommendations?

 

[aye mate]

OK I put an MR2 alternator on which is 100amp. The batt. and brake light are not on now, but when I was driving home last night all my lights started to go dim and the car died.(Been driving about 25-30mins for the whole day) I go back to the car this morning and was able to bump start and drive it about 5 miles home and just barely made it in the driveway.
Some how the alternator is NOT charging the battery. I replaced the alt. fuse in the fuse box. Is there another one in the power line somewhere(IE fusible link) I thought that the one in the fuse box was our fusible link?

 

[shaeff]

you can get brushes at any carquest, napa, autozone, advance auto, etc...

aye, that's really odd. i cant think of a reason right now why it'd do that. (i think i was up way too late last night. )

-shaeff

 

[kewlcoconut]

aye, the only thing i can think of is for you to recheck all the fuses, and the connections on the alternator. the grounds and everything hooked up to the alternator. and you said you got an mr2 one right? hmmmm....i highly highly doubt that your alternator is fried. check the copper wires in it, make sure they look well, copper lol. otherwise if they are brownish/black, its dead.

 

[aye mate]

Does anyone know if there is another fusible link in the wiring? The power wire goes to the fuse box under the hood and theres a 100amp fuse in there that I replaced just to make sure. I was looking at the wiring diagrahm in my Haynes book and it looks like one of the 3 wires that plugs into the back of the alternator has a fusible link in it. Can anyone verify?

 

[aye mate]

This might help too. I charged the battery with a charger and tested the battery with a volt meter 12.28 volts. I then started the car and tested with the voltmeter with the negative prong on the negative battery terminal and the positive prong on the power wire where it attaches to the alternator. 12.28volts. I'm not totally sure what that means but from my understanding it should read higher with the car on because of the alternator charging.

 

[IJ.]

Should be charging at around 13.8v AM.

 

[aye mate]

Does this mean my battery is bad? The alternator is a brand new 100amp MR2 alternator. Also from my research there is a fusible link inbetween the alternator and the 100amp fuse INSIDE the fusebox. If this FL was bad the car wouldn't start correct?

 

[IJ.]

Once it's running the battery has no effect it should run on the Alt without the battery at all.

 

[aye mate]

Then whats wrong with my car? It appears that the car is ONLY running on the battery and the alternator isn't doing anything.