alternator problems

[nappy4612]

     My car seems to have a crazy problem.  the original volt gauge works is showing me that the altenator is not working. I put oin a new alternator, voltage regulator, and a new resistor. and the car with all that it still seems that the car is not charging. The gauge shows that the car is sucking power. I think it mite be the start relay or a wire where do I start. Please help

[Rolling_Thunder]

first i would verify that your alternator is indeed putting out power...    if the gauge shows a draw i would start by simply unplugging the headlight harness, then the engine harness - between both seeing if the draw stops - then you would have narrowed it down some

[nappy4612]

unplugeed the harness and the gauge is showing the same. But less draw from the battery. I will go get a new alternator today and a new start relay. If that don't work I will run all new wiring for the alternator. Or just cut open the harness and see if the is anybreaks or wire problems.

[Plumcrazy]

It always helps to tell people what year your car is. 

[Nacho-RT74]

Or maybe just specify if is double or single field alt

[nappy4612]

 sorry its a 69 and it is a single feild.  Abody know what is the right alternator for the car. I got one from napa it is a 12volt 60 amp and it is not chargeing the car I pit on a lamp tester to the feild and the power output and it bearly makes the lamp light up.

[Nacho-RT74]

Check you have with ignition key on RUN position power on regulator input ( blue wire ) and on field wire ( green ).

Regulator must have good ground. Being a mechanical regulator, as far I know is a pulsating signal, but really fast pulse to give average power, and increased with faster pulses to give more input to alt.

how much RPMs did you make the test ? tipically Mopars alts doesn't provide a good charge at iddle.

For a good alt testing ( single field ) without dissasembly you need:

5-10 Ohms between brushes

Isolated field brush ( positive )

If you are able to remove both brushes and get access to rotor tracks, then be sure you have ungrounded rotor coil. Just continuity between tracks, no chassis.

Rest of test are dissasemling rotor back housing ( with stator ) to test diodes and stator. Is not hard.

negative diodes are tested using black tester wire on chassis and positive on every diode terminal... it should get reading... around 200 Ohms as far I remember I got when I test

Positive diodes are tested reversed multitester wires between diodes terminals and Alt stud... same measurement

Actually I can remember exactly wich tester wire order, black or red where, is used to check positive and negative diodes, but if is not on one way is the oposite so you will find at the moment. Needing to get filtered pole, if you want to get negative, you need to get it at at output so it should be as I told you.

Of course also test stator... Stator consit on 3 parallel coils with common start point and then each coil ending on avery pair diodes ( one negative one positive )... thre colis must gives you continuity.

Shame is not Double field alt. They are are easier to check. With stator exception, everything can be checked from outside, and rotor continuity and isolation is easier since both brushes are isolated.

[Plumcrazy]

sorry its a 69 and it is a single feild.  Abody know what is the right alternator for the car. I got one from napa it is a 12volt 60 amp and it is not chargeing the car I pit on a lamp tester to the feild and the power output and it bearly makes the lamp light up.

Does it have two field wire connections?   
If so you must remove the insulating washer from under one of the field connections and replace it with a metal one.  Just be sure to connect the field wire to the other field wire connection.

Also make sure you have battery voltage at the output wire when the engine is off.

[nappy4612]

  Thank you all for the help. I found out it was a bad feild wire. I guess when thay put in after market guages in it they cut open the harness to install the wireing they nicked the field wire.