rebuilt alternator 3 times still not working

[weewajr]

So i have been having a ongoing issue with my charging system, the battery would slowly drain out as your driving it and shutting off and re-starting the car over a few days. So i replaced the battery and that didnt fix the issue, took the alternator to a rebuild shop they "rebuilt" it but it only charged for a matter of minutes before it stopped working. Took the alternator to another shop and they fixed a couple other things in the alternator but showed me it working on the bench. So i installed it and same thing, it would charge fully on its own for a few minutes but then it would start draining the battery again. When using a multi-meter to test the alternator it is showing readings from 10 volts to 20, it sparadically jumps around when you rev the car, at idle it just sits at about 11 volts. but when the alternator is bench tested it charges as it should. is there anything that i should be looking at as the cause of this other than the alternator? any help is appreciated! :thankyou:

 

[AREA 91]

Sounds like a bad voltage regulator too me.

 

[weewajr]

the regulator was replaced it still bench tests fine just does not work properly in the car

 

[ManySHOs]

Are your alternator brackets powdercoated?

What condition are the cables in/connections/regulator plug?

Ian

 

[Toul]

If it benches fine, big3 upgrade, if that doesnt work then try swapping it out for a known good one instead of yours rebuilt.

 

[ManySHOs]

If it benches fine, big3 upgrade, if that doesnt work then try swapping it out for a known good one instead of yours rebuilt.

If it benches fine the problem is in the car itself. Upgrading to a 3G alternator isn't going to fix anything unless there is a ground problem in the AC compressor bracket or alternator bracket. I did have a similar issue with my 90a alternators so I upgraded to a 3G from a 94-95mtx. Along the way I upgraded all of my cables to 2 gauge and haven't had a problem since. I suspect that my issues were from my powdercoated brackets which might not have provided a good ground path. I had ground down the contact points to bare metal but I don't think I did a good job with it. I spray bombed the new 94-95 AC compressor bracket this time around and upgraded all of my connections with the new cables.

EDIT: I just noticed that the OP's car is an ATX. I don't think the 3G upgrade is going to work unless there's a non SHO donor car that uses one that will drop in.

Ian

 

[SHOZ123]

Is there a loose connection or intermittent short on the alternator output wire? I've seen the voltage jump like that when the alternator does not have a good path back to the battery.

 

[weewajr]

the output wire looks good atleast until in goes down into the loom. how would i test for a short on that wire?

 

[SHOZ123]

It would have to be intermittent and the fuse links would have to be good.

An ohm meter would tell the tale.

 

[weewajr]

So i have been slowly battling this problem for a couple months now, and for an update i have had the battery tested and it checks out well, the alternator has been checked by a reputable shop 3 times and it is still good. I went out to the car one day and wiggled the wires around down at the starter and it worked for a couple days, then driving home one day it just started fading and died again. So i cleaned up the connections down at the starter, i have followed all the wiring and they look good, fuses are all good too. Now one thing i noticed, on the starter solenoid there is a black plastic cap looking thing that the terminal is attached to it will spin back and forth maybe a quarter inch or so, but the connection is good. Could that be the issue? could the solenoid need replacing? the car starts just fine when it has power. And another thing is the plug for the alternator, it can be pulled on and off pretty easily. Oh ya, the battery light does not come on at all now. It worked before and now even when its not charging while running there is no light.

 

[SHOZ123]

Have you replaced the cables?

 

[weewajr]

battery cables have not been replaced. i have followed all of them and they are not showing any wear and the ends look good. they look like they were replaced at some point fairly recently.

 

[NJSHO]

I had three different rebuilt alternators from stores and non of them ever worked correctly even thought they "benched" correctly. When I tried to have shops (as in more than one) rebuild my original alternator, nobody would touch it and the term pandora's box was mentioned a couple times. My problem was steady voltage at idle, but once the rpm's went above 4g my autometer gauge would slam between 10 and approx 18 volts. I checked all wiring and grounds for about 6 months with the 3 different alternators. I ended up buying a new, not refurbished, alternator and all has been well since.

 

[SHOZ123]

Yes you need to test the voltage with a voltmeter at the battery while the car is running with a full load.

You can also do a millivolt drop test when the car is running to test the cables.

 

[weewajr]

i will test the cables later today. What about the solenoid cap that wiggles or the alternator plug thats loose? would those cause it to not charge?