walterrao

Well Hopefully some of you guys can help me, so here is my problem.

When you first start the car the alternator charges normally, to about 14v or 14.5v but then soon it starts to get heatsoaked, and the voltage drops to 12 volts or sometimes even less. The alternator is charging at full amperage but it is not enough to keep the voltage up. Something is using up too much current, but i cannot figure out what it is.

I have already tried swaping alternators with a good one from another car, and still the same problems. I have tried unpluging things shuch as the blower motor and the fan motors but it seams to still have the problem even when all the accesories are off. Just with maby 13.1 voltage instead of 12.2v with all the accesories on.

I have also done a voltage drop on the wires going to the alternators. there was maby .1v drop on the exciter wire that comes from the fuse. and no drop on the other wires.

I am stumped. I dont know were to go next. If any of you have seen this before or you have any ideas what to check, then please help me out.

Thanks -Walter

jv9999

iTrader: (1)

How do you know the alt is charging at full amperage? How are you measuring the voltage? Not with the dash gauge, right? What happens if you run it with the alt disconnected with a volt meter across the battery and no accessories on? Does it hold 11V or better? The only thing that could draw that kind of current without smoking is the starter. Seems unlikely though.

walterrao

I am measuring voltage with a multi meter. I have not tried runing it without the alternator. I will try this tomorrow, but what would that prove by holding 11 volts? Im pretty sure It is charging at full. it is whining and getting hot quick. and it also did this when i swapd alternators

I was Thinking about the starter, but i dont understand how it could draw amperage without being used.

thanks for helping

jv9999

iTrader: (1)

It would prove that there isn't a big load and that something is likely wrong with the alt or the alt wiring. That alt is good for 100A, if it was really putting that out something would be getting hot including the alt itself.

This might help you troubleshoot: http://www.alternatorparts.com/cs130_sbpage1.htm

Timmie

I have an 91 V6 with the exact same problem.
if the car is cold, it will charge,(14.6 V) if it is getting hot( it doesnt charge anymore and i'm stuck on 12V. ( maybe 12.5 to 13V if i put all accessoires down )
from the moment I put 1 accesory on, doesn't matter what ( lights, heater,...) it looks like the amp can't pull it anymore and goes back to 12V.

so it looks like something is really asking the maximum out of the alternator.

I already changed the batteries and have 2 alternators both have the same problem.

if anyone here knows what the problem is, pls tell me.

Timmie

can you look at the cable going to your starter, the big black 1.
mines isolation is completely screwed at the last 10 inches.
So I guess my problem has somethig to do with the starter/connections/cable

Saculia

iTrader: (1)

I had a similar problem and this is how I fixed it.
Cleaned and tightened all grounds that I could find in the engine bay and both battery terminals.
Replaced the alternator connector and grounded the new connector to the alternator bracket. In my car the old connector wasn't making very good contact where it plugs into the alternator. Unplug the connector and look for corrosion on the inside of it, where it plugs in. After I did all of that, my car started running a lot better and smoother.

Timmie

dit test it with a seperate connector hooked up straight to the battery already ( didnt help )

it has something to do with the starter/wire/connection

LouStugots

iTrader: (1)

had a similar problem on a different car, when the car was running the volts would constantly jump from as low as 10v to 14.5v so quickly that if you stared at it for 10 seconds ud see evry # in between. turned out the nut for the positive connector on my starter was loose and every bump i hit was draw enormous amounts of power. was an easy fix for me.

Saculia

iTrader: (1)

I don't know if this is the connector that you are referring to, but the one I had a problem with is the connector that has two wires coming out. One goes to the fusible link, the other to the fuse block.
Poor starter connections will definitely give you problems too. That's why you need to check all connections and grounds under that hood.

Timmie

its that connector that i mean. took a spare connector I had lying around. soldered a brown and red wire to it. and connect the red wire straight on the battery and the brown wire on a hot in run wire.
didnt help anything. problem assisted.
also the thick wire coming from the alternator is put on very tightly.
but the wire on the starter wire is toasted.

Saculia

iTrader: (1)

I guess you found your problem.

Timmie

already found that part yesterday

the question is, is it the starter, the cable , or the conenction between them.

Saculia

iTrader: (1)

The first thing to do is to make sure you have good connections (can't have a good connection if you have a bad cable). Then if you have to, worry about the starter.

Timmie

I don't have a workpit and the ground outside is ICECOLD these days.
with other words, I wanna be finished with the problem in one time.
meaning I'm probably gonna put in my backup starter anyway.
just tp play it safe.
and then I can open up the old starter to se if anythings wrong with it.

walterrao

Well here are some updates of what Ive done.

1. I replaced the ground wire from the battery to the block and the chassis.
2. I checked the positive wire to the starter and alternator both show no voltage drop. they have full batt voltage to the starter and alternator. The starter and alternator are both new.
3. I let it run with the alt. disconnected. with all the accesories on. and it was settled on 11.25 volts. so i dont think i have any massive drains.
4. I put a jumper wire from the batt to both of the wires on the alternator connector.

But to no effect. the alternator is still only putting out 12.6-13.2 with the accesories on. And its screaming like a banchee. And getting real hot.

Where is the ground wire on the alternator your talking about. doesent it ground directly to the engine through the case?

Ive already tried swapping out alternators with my car, this is my roomates car im trying to fix. The car is a bone stock 91 z.

walterrao

I just replaced the starter. i warrentied it out. the car still has the same problem. anyone have any ideas. please

Timmie

I solved my problem.
looks like it was the alternator.

I had 1 alternator with a bad diode.
this one got extremely hot and didn't charge at full power anymore then.
if I put my lights on, the alternator only putted at 12.3, 11.9V ( actually I was running from the battery then)

the other alternator charged the full 14.7 V, but after a couple of minutes it also falled back to 12V.

after I found out about the bad diode bridge of the first alternator, i putted in the diode bridge from the second alternator so that i had 1 good alternator.
my car works fine now.

think alternator 2 has a bad reulator ( + a bad diode bridge NOW )