Having a starting problem.

[kiway22]

I replaced the starter on my '97 aurora. with a new starter. At first cranking the car was okay. Then it stopped starting after awhile. I checked the battery, and it's voltage was okay. But it was about 10 years old, so i replaced it. She started up, but after awhile the battery went down. So i replaced the alternator, since it was over 15 years old. The rebuilt alternator Seems like it wasn't during anything. But after cleaning the ground cable on the car body. That seems to have fixed the charging problem. I think the starter that i purchased is defective.