alternator question

[64dartsb]

I have a  71 dart with a slant six and I'm experiencing slant sickness.  My alternator won't keep the battery charged and the alternator is brand new so I don't know what's wrong and the wiring is the same as it was before.  I can take the batt. out of the car and charge it and it will hold a charge but then the car will drain it and when the car is running I disconnect the batt. cable and the car shuts off.  I checked and the engine doesn't seem to have a ground could that be it. Also when the battery is sitting in the stock location should it be sitting on metal or should there be some sort of barrier like plastic or wood or something so the battery doesn't ground itself out?   

Thanks for the help I really appreciate it

-matt

[68_Val_Sedan]

you will need to make sure the engine is grounded.. the negative bat cable usually runs to the engine.  there should also be a small cable on the back of the motor that runs to the firewall.  if it is not there use a 10 or 12 gauge and make one up.  As far as the ALT not charging, It sounds like the voltage regulator is shot.   should be a black or silver box with a 2 prong connector with blue and green wires on it.  try replacing it and post the results.

[cu440da]

Also, never assume the new part you just put in actually works. After getting a few bad alts right out of the box I always have them tested before I leave the store. You'll get a few odd looks from the counter guy, but it beats pulling your hair out trying to figure out why the problem persists after a new part is installed.

[gregpurcell]

I always test my alternator by pulling the battery cable and seeing if the engine stalls (like you said yours does) If the alternator is charging the motor will keep running. This only says the CHARGING SYSTEM is not working. you could have a bad regulator. Basically however, if the thing runs with the battery disconnected, the charging system is doing the work.

[64dartsb]

ok thanks I'll try the regulator today and if that doesn't help then I'll have the alt checked out

thanks

[NYrr496]

64DartSB, do you have a multimeter? Check voltage across the battery with the engine running. Check it on the positive stud on the alternator and at the voltage regulator. You can check it right on the car.

[64dartsb]

What should it read off of the alternator?

[68_Val_Sedan]

when the motor is running you should get about 14 volts at the big stud on the back of the alternator, if everything is workign well.  if not try the voltage regulator.

[NYrr496]

Yeah. 14, 14.5 VDC. Check the stud, the input side of the regulator and the output side of the regulator. That also checks for open wires.

[64dartsb]

ok sorry I've been away from the computer for a while.  But I had a new regulator so I put that in and it didn't fix it.  I will check the alt. the next chance I get.

-matt