This is not on an S2k but I'm trying to help someone out. I vaguely remember covering this issue in a college auto class but thats been 7-8 years ago and I've forgotten some stuff. The car will click the starter solenoid but wont turn over. When boosted off it will run but as soon as the cables disconnect it will die again. The guy has tried throwing an alternator on it with no avail. I will be checking it out tomorrow with a multimeter and looking for proper voltage but I swear there is something they told us in that class that if this happens it's most likely ___________. Ring any bells for you?

The car is a e36 BMW

 

new battery?

 

yea, old battery not holding charge?

 

You need a battery.

 

did you guys not read? the car dies when it is jumped with cables as soon as cable are removed. that means the car is not making electricity. that means that the charging system has problem.so the battery is probably dead and needs a reconditioning or a new battery as the alternator is not charging the battery. but he needs to get the alternator / charging system checked out first. he replaced the alternator with a known GOOD alternator? if he did, and it is still not charging, then it is the regulator system that is not the alternator itself. car modded? might be things connected improperly. but the battery is not the main culprit, it's just a victim of the charging system. stop posting if you are guessing and are otherwise clueless about things. clutters things up and spreads ignorance.

 

no, he needs a working charging system and to make sure that the current battery can still hold a charge. learn know something before you post a nonsense 4 word reply.

 

As far as the electrical system is concerned a battery is only needed to get things running, correct? It's my understanding that after it's running the alternator and voltage regulator should provide all the electricity thats needed. If he has put a new alternator on it then there must be a problem with the voltage regulator or something stopping the current from flowing. If a fuse/link was blown somewhere or the regulator was restricting current flow then why would it run while on the cables? Guess I'll see what the multimeter reveals.

 

ive purchased an faulty alternator before.. its not a uncommon thing. check your grounds and your alternator out. once the car is started the battery doesnt do anything except feed off the alt. for recharging purposes..

 

a bad alternator was what i was thinking as well.

 

Get the car started then connect a multi meter from the postive connection on the alternator and then the ground on the multi meter to a good ground. You should see between 13.8-14.2 area in volts in the alternator is working properly. Good luck!