Alternator problems

[Rebel]

hi all,
I have a 5.0L 1990 GT, the alternator has stopped charging the battery, is there any way of testing the alternator?
I've heard something about an upgrade called a 3G upgrade, but unsure as to what this is, anyone know?

 

[broncojunkie]

Later models use a different alternator. More amps and the wiring is set up a lot better. The spade plug in the old style alternators can be a fire hazard, so the swap makes sense for a few reasons. The old one is also too weak...especially if you run under drive pulleys or have anything extra putting a load on the electrical system (upgraded lighting, stereo, electric fan, etc).

The upgrade will most likely require a little grinding on the inside of the alternator bracket, since the 3g is slightly bigger. On my f150, it took about 5 minutes with a 4" angle grinder to clearance it enough. Very simple. You'll also need to buy or make a heavy gauge cable to run from the alternator to the starter relay on the fender. Again, very simple. I made one myself by purchasing a battery cable and soldering lugs on each end...all available at the local parts store.

You can take your alternator off and have it bench tested at any parts store. Best way to test them imo. Good luck.

 

[Rebel]

Thanks for replying. If I was to change the alternator for the 3G one, which one do I need to buy?

 

[broncojunkie]

There is a list of which ones will work, but I couldn't begin to tell you where I found it online. You may as well stick with 130a alternators. The 3g is available in different version, such as 100a. More is always better because it just means it doesn't have to work as hard. So keep that in mind. But I'm pretty sure the ones that came on the 94-95 model mustangs were 130a and will fit. There are other vehicles though. I want to say some of the t-birds and Taurus models will work. You should be able to compare it to your old one. The way it is "clocked" makes a difference. The plug should be close to the location of the old one, to make life easier. The bolt pattern needs to be the same, of course. I have one ready to go in my 88GT and I believe it came from a 99 v6 mustang. It may be less than 130a, though. Not sure.

 

[Blown347]

It depends on your budget for a 3G. Latemodelresto sells a nice 130 amp 3G. But if you want something cheaper, go to any parts store and just buy an alternator for a 94/95 mustang, I know autozone sells a few models that are 90 and 100 amp. That's what I have in one of my foxes. It works fine, but it didn't like underdrive pulleys so had to pull them out.


IG: leesweitzerracing
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[Rebel]

Thanks for the info, I don't think I have any under drive pulleys on mine, unless they're fitted as standard from Ford.

 

[broncojunkie]

If you really want a cheap one, you can get a used one. I paid $20 for the one I'm using from the '99 v6. I just looked it up and it is, in fact, a 130a. I've read that the remanufactured ones are really hit and miss. From experience, I'd say that's true. Aftermarket ones are never as good as factory. I just plan on putting a brush set in this one, cleaning it up, and calling it a day.

 

[Rebel]

Sounds good to me, I'm going to check for any earth problems in the morning. If that proves to be ok I'll look into replacing mine with a newer one.
Thanks

 

[broncojunkie]

Blown347, I'd love to buy a new one. They look good when they're new. That's what I did on my f150. I'm hoping I can figure out a way to restore the used one to look nice and bright. I cleaned it up with some heavy duty cleaner and a small brass brush. It looks a lot nicer, but still not bright like the new one on my truck.

Any ideas how to get cast aluminum to look new again? I've used the "aluminum brightener" acid stuff at work. We've got aluminum diamond plate down as a floor in our lower engine room (on the boat.) I think it would work great, but I'd be afraid of getting it on the copper windings. I'm sure it would work great if I can take it apart, but I've never dismantled an alternator. You guys ever try it?

 

[ALMOST STOCK]

I think it would work great, but I'd be afraid of getting it on the copper windings. I'm sure it would work great if I can take it apart, but I've never dismantled an alternator. You guys ever try it?

When I polished my stock alternator I took it apart ... taking it apart was easy it was trying to keep the brushes in place when I put the 2 halves together was the pain. I decided to use a small piece of scotch tape to hold the brushes in place while I put the 2 halves together ( it worked like a charm) and once I had everything bolted back together I spun the fan a few times and the scotch tape was gone.

This is how to rebuild a 3G which shows you how to dissemble and reassemble it.

 

[John2002]

I put this one on last year...now I can have the head lights and turn signals on at the same time...didn't need to up grade the wire harness or file down anything to make it fit....head lights are brighter then ever....

 

[broncojunkie]

John, does your new one still use the old spade connector? And 95A is still a pretty good improvement over stock. I think that's what it should have come with from the factory. I like the idea of getting rid of that connector, but I don't think it's an issue as long as you still have the fusible links wired in. I think the problem comes from people burning up a fuse link or two and then just cutting them out and splicing the wires together. Then, you don't have any protection if one of the wires gets pulled out...which is easily done on an old, plastic spade connector. You don't have that issue with the 3g alternators because you have a heavy gauge wire (I think I used 4 gauge on my f150) with a lug on each end, which would take some real brute force to yank one loose. The 3g, instead of having a plug for the spade connector, has a stud with a nut on it. I also wired in an ANL fuse holder...150a, I think it was.

 

[Rebel]

I put this one on last year...now I can have the head lights and turn signals on at the same time...didn't need to up grade the wire harness or file down anything to make it fit....head lights are brighter then ever....

Thanks John, where did you buy it from?

 

[John2002]

Latemodelresto, Mustang site...I had to cut the old clip off and use solders connector for the new clip that came with the alternator. I was a bit concerned about cutting it off, direct fit to me means that you take the old one off and put the new one on...it took a few more minutes to do the splice. The direction that came with it were perfect...