91tpi-zf

Well, I am on my second AC-Delco Alternator. It all started when my factory alternator went out at the track (It had been rebuilt 1 year earlier). I decided to get an AC-Delco to replace it. It worked OK for a couple of days, then it would sometimes charge and sometimes discharge, depending on its mood. I also saw sparks coming out of it at night. So, I got another one to replace it. When I picked it up, it appeared that the fan? on the inside of the alternator (not the one on the front) was made of some type of plastic or organic material. Well, it worked fine until I took a friend for a ride. I noticed it discharging so i looked at it and could see that the plastic? fan inside is all broken. Has anyone else had this problem? I am turning 6400-6500 rpm.

Black ZR1

I've lost track of how often I had to replace the alternator in my 91.

The last time, the mechanic suggested paying a few more bucks and get a better Delco.

I did. It's been over a year and no problems.

Flame Red

91:

I used to go through alternators like gasoline The last one I had disintegrated the front bearing when I was on a dyno, and the fan blew apart That was a Pep Boys unit with thier life time warranty; guaranteed for you to spend your life time replacing it.

I replaced it with a Powermaster and have enjoyed six months of no trouble service. I'm guessing that if you are going at 6000 RPM that your alternator is going about 20,000 RPM or so!

Flame Red

samc

flame red - where did you get the powermaster?

89 Bob L

Many ocassions the alternator goes bad or has a short life is due to the connections and grounding. Whenyou replace the alternator clean all of the brackets where they come into contact with the alternator. Clean all bolts with electricat cleaner. The positive line, red wire with a black cap should also be clean, using a wire brush on the connections. The most IMPORTANT part of the installation is when you tighten the positive bolt. DO NOT OVER TIGHTEN. Hold the wire when you tighten the bolt to avoid fracturing the internal plastic assembly.

bill mcdonald

sounds like the bearings might had failed and the fan may of hit the outter edge of the inside of the alt case?

if you spin it by hand is it stiff or does it squeel?
ever taken an alt apart?

91tpi-zf

Well, you cant really turn the alternator because of the plastic pieces getting hung up. It appears that the bearings are fine though, because there is no side to side movement of the shaft, etc. I am going to try another one and well see how it will hold up. If it doesnt, I guess its time for the Powermaster or something like that. By the way, does anyone know how much the Powermaster alternators run?

Z52 L98

Chris Petris sells a 140 amp AC Delco alternater that he machines for a direct bolt on fit to replace the puny stock alternater. It has worked well for me for over a year now. I don't have his contact info with me, but look in Corvette Fever Magazine and you'll find his column and contact info.

Black ZR1

try here

http]//www.bloomingtongold.com/pdfs/BGRegBro.pdf