Who wants to rebuild my alternator?

RVR OVR

Well-known member
Dec 9, 2004
176
13
IL
1995 Discovery 1

Been trying to fix an alternator issue far too long. Here is the backstory...
  • Installed an amplifier and rear subwoofer.
  • Ran into issues with the battery running down over time. Bought a new battery. Problems persisted.
  • Went to Autozone and they use their little alternator tester and it tested alternator as "good". A tester I have at home on my battery charger said the same.
  • Assumed too much power draw from the amp so had a shop in Chicago "rewire" my alternator to 160 amps.
  • Things seemed better, but problems persisted.
  • I bought one of those cigarette lighter voltage meters that should show the amount of voltage getting to my batter from the alternator, here is what I see:
    • Upon startup, things are good. Anywhere from 13.x to 14.0 volts show.
    • All while idling:
      • Power on radio, it dips some.
      • Power on Fan on full, it dips more. It generally stays in high 12's to low 13's
      • Car warms up, put it in gear, meter shows 11.x, and occasionally can drop lower while sitting at a stop light, especially with radio, fan, and lights on.
    • Driving along, it gets back up into the 13's
  • I also replaced the belt and the pully to be sure those were not issues.
I spent money to have it set to 160amp and don't want to do that over again. I don't think any "non rover" enthusiast will know how to fix the rest of it correctly, so I don't want to go back to the shop I used before.

Anyone willing to take payment and rebuild whatever is necessary to get the low RPM power output back?
 

lunchbox

Well-known member
Apr 20, 2004
1,985
86
48
St Louis, MO
I can offer zero help on the rebuild. But I am curious as to what you’re using the 160 for. Is it just for the stereo? I have a giant stereo running off of a 120a alternator with no issues. I have two Yellows and a 1f capacitor on each amp. I’ve ran old school PG amps that like at least 14.4 in the past. For them I used an AccuVolt to get it up around 16. I’ve always wanted a larger output alt for my truck. I’ve had some in the 200v range in other cars. But aside from finding an mean green, I’ve given up.
 

RVR OVR

Well-known member
Dec 9, 2004
176
13
IL
Yes, it is just for the stereo. I do have a winch on it but this car never goes off road anymore. I did some math and it turned out that it is what I needed.

While this is my car, my son drives it 99.9% of the time. I just took it for a ride and watched the voltage on a monitor. It can drop at a red light while waiting but while driving, it is always at 13.8 or 13.9. I suspect he is sitting around idle a lot or something that the battery keeps draining.

I am going to get a new alternator and see what happens.
 

4Runner

Well-known member
May 24, 2007
515
45
Boise Idaho
There is another recent thread about a continuous voltage drain. I can be the alternator but it could be lots of other things as well. Changing the alternator to see if the problem goes away couldn’t hurt if you have another on floating around. 11v is too low anytime your just driving. You mentioned the amplifier install, is that when it started? Sorry for the dumb question but does your amp turn off with the key? Sorry, I know, just trying to rule out some stupid things.
 

RVR OVR

Well-known member
Dec 9, 2004
176
13
IL
Yeah, the amp does turn off. I don't think I have any voltage drain while the car is sitting there. If the battery is fully charged it can sit for a week and start right up no issue. I think my son sits with the car idling and listening to music a lot and that gets him into trouble with accessories turned on. Bottom line is that when idling, it should still be above 13v and charging, not jumping all over the place and dipping into the 10's or 11's. I ordered a used alternator for Will Tillery and am going to see how that works and go from there.

I would just go to the 120amp Rover one, but I don't think that is an easy swap - i have seen other threads and people needed to swap out their tachometer as well for a 95.
 

lunchbox

Well-known member
Apr 20, 2004
1,985
86
48
St Louis, MO
I get mine from oreilly auto. 120a with lifetime warranty. Direct swap into my 98 D1. Do you have a capacitor on the amp? My buddy had one with a voltage indicator on it. It was killing his battery. Very odd
 

RVR OVR

Well-known member
Dec 9, 2004
176
13
IL
No capacitor on the amp. New alternator will be here on Tuesday. Will see what happens after that.
 

robertf

Well-known member
Jan 22, 2006
4,511
198
-
I just rebuilt one of mine. First time in probably 10 years Ive seen voltage in the 14s