This is a bit long, but it all started two weeks ago when I decided to tighten my alternator belt.

I've got an 88 GTU with no airpump, and had installed a dual alternator pulley on my alternator which was pretty old to my knowledge. The battery is a duralast that I just replaced a year and maybe 11k miles ago. The new belt had less compliance than the old one, so it was tighter. Over time the old one had effectively stretched and gotten looser, and so was making a little bit of noise. So I loosened the two nuts and used a crowbar to raise the alternator and tighten the thing up. I didn't measure the deflection, but it was significantly tighter. It still seemed like it had some play in it, so I thought it was fine. 6 days later, on Friday, I noticed on the way to work that my voltage was reading pretty low on the stock gauge. I don't always trust the thing, but it was consistantly under 12 volts with the radio and A/C on.

I noticed on my 20 mile drive to work the voltage decreasing slowly and figured my alternator was fucked. I cut off my radio and A/C and made it to work. I decided to leave early and see if I could get it back to my parents house. On the way it quit on me--it was like watching a time bomb; the needle went 12-11-10-9 and then started bucking and **** when it didn't have juice for ignition. I pulled over, got it jumped, and limped the car to a friend's garage about two miles away on 10 volts or so. I didn't have access to a multimeter, but I just pulled the alternator and took it to a shop to get rebuilt.

Today I finally got the alternator back after having it upgraded to 100 amps. I put the thing in the car and tightened the belts and everything--maybe a little too tight again. The battery was close to dead, but my friend had an industrial-style battery charge that I used for a quick start. Then I let the thing idle and it was reading a little under 12 on the stock gauge (still had no multimeter). After 5 minutes of idling, which I hoped would charge it a little, the thing died. Then I set the thing to a 40 amp quick charge and let it sit for about 25 minutes, then quick started the car with the battery charger. I tried to drive it home, which was about 15 miles away, but the voltage kept reading a little under 12. At this point I was convinced that I had killed my battery when the alternator appeared to quit on me. The thing dropped to about 9 volts and died on me about 7 miles away. So I jumped in my friend's car, who had been following me, and went back to my parents house. I cannibalized the battery off my dad's car and brought it out to the 7.

I swapped batteries and limped the car home. Voltage still read a little under 12. Finally I got a multimeter on the thing idling with pretty much no accessories and it read 12.4 . I turned the car off and it actually read higher--12.6 . I loosened my belts a little bit and checked voltage again quickly (this was 1 AM and I was running out of patience). I put that battery back in my dad's car and it read 14.6 .

Obviously my alternator isn't doing ****. Could the belt tension cause that? Did I somehow not put the two electrical connectors in right? As far as the battery terminals go, I was sure the positive one was tight. The negative terminal is kinda messed up after 18 years and is tricky to tighten, but I put it in there solidly by hand for testing in the garage. There is no corrosion on the connections.

So what gives? Any thoughts? Somehow I screwed the alternator up.

 

the number one cause of electrical issues in a seven is usually bad ground connections. i bought a fd alternator and i was only seeing 12-13 voltes. after i clean all the ground connections, i saw a constant 14 =]

as for the battery terminals, get some new ones if the old ones are shot. easy to do. just buy 2 connectors for 5$ at any auto shop , cut the old ones off and splice the wire, tighten the 2 new ones on. done.

 

the #1 cause of charging issues though is bad positive connections. when the positive cable on the stock alternator begins to corrode it just gets worse and basically melts the positive post extension. remove the extension arm and clean all the contacts and the ring terminal that bolts onto it as well inspect both ring terminals at the 80 amp fuse under the hood and be sure the fuse is still in one piece. last thing to pay attention to is the battery terminals, be sure the wires in them are tight and that the terminals are clean and tight. the focal point of this is to be sure the contacts of the positive wire to the alternator is actually getting to/from the alternator and that the 80amp main fuse is not blown.

 

my charging problem i had for a few years on my 7 was the power cable to the alt. i took it to a shop that specializes in the charging systems of cars and when he split open the housing of the wire it was corroded and when i replaced that it was all gone

 

the heat from the bad connection at the ring terminal usually will cook the wire and terminal but you can put shrink tubing over it and clean up the terminal to save it but if it is bad enough you should just crimp a new ring terminal onto it.

 

So where is this 80 amp fuse? Do I just follow the wire from the alternator ring terminal thing right to it? Is it a bitch to get to?

I'm going to clean all the contacts and replace the ring terminals then.

 

^ Actually the stock 80 AMP fuse should be in the regular fuse box. Silly question.

oh and what about running a wire from the ring terminal on the alternator to the positive terminal on the battery, maybe with another 80 amp fuse or something? Good or bad idea? What gauge should I run if I do this?

 

and although no one has covered it, yes improper belt tension will distroy the alternator. Too tight and it puts way too much stress on the bearings for the shaft of the alt, and can eventually cause contact failure as well as bearing failure.

 

Even if the belts had been too tight, it only ran that way for about 30 minutes total since I got the alternator rebuilt. Hopefully that won't kill it. The guy at the alternator shop didn't make any comment about ruined bearings or anything, so I'm hoping I'm ok.

 

did he replace the brushes in the alt or just replace the regulator?

 

he replaced everything. He even sandblasted and painted the thing with a two-tone scheme. I'm not worried about the alternator itself; this guy does really good work.