Cadillac Repair: 96 cadillac wont start sometimes, cadillac sedan deville, positive cable

Question
I have a 96 cadillac sedan deville that i just bought last week and i test drove it twice and started it up several times before i bought it.  then out of the blue my brother went to start the car and it wouldnt start. when i go to start it all of the lights and the radio work but it wont start.  then the car remote would not work and no lights would work so i checked the battery and when i touched the ground cable all the lights came on but would not start, it just makes a single click, if i slam the door several times and turn the key 3 or 4 times it will start.  the reading on the dash for the battery was around 11.4 but when running the reading was 13.8. the shop i purchased it from put a new battery checked the cables and it was fine for a day or so then it did it again.  now they said the connection to the battery keeps coming loose and the are going to order new connections. does this sound right?>

Answer
Hi Barry, If that was the original battery then it wouldn't surprise me that it was going bad. The fact that the battery cable bolt(s) are loosening up doesn't seem right to me and I would hesitate replaceing them. There was a bulletin that wanted a washer installed under the positive battery bolt so it could tighten up both cables tightly. I have seen where the battery acid has leaked into the positive cable and that would be a good reason to replace it. Also if you have a northstar where the negaive battery cable attaches to the LF of the engine block tends to loosen up. If 4.9liter remove the neg. battery cable near the starter and make sure it is clean and tight. The pellet in the ignition key might need to be cleaned or the key replaced. Did you try the other key when the engine didn't start? Then testing the starter especially when it doesn't start might show a bad starter or starter solinoid. The big key here is to have the car at the shop and let them test/start the engine until it doesn't start and then they can nail down the cause. Alternators should keep the voltage around 14.3 volts so if with the new battery it is still around 13.8 volts then you might need a new alternator or cleaning the engine grounds/negative battery cable end where it bolts to the engine. Hope that helps. Bill
P.S. I recieved the original post and thought I replied with the above message although I'm at a loss why slamming the door will get it to start. I have to agree that something is loose be it the neg. or pos. cable or something else. Maybe something loose on the ignition switch connector. In any rate haveing it at the shop and testing for where the power stops and then slamming the door to see if the power is then sent down the line will be necessary. Not much help I can offer other than find a good shop and work with them. Bill