Crap! Have the car about 3 weeks

[Dustdevl340]

70 Duster 340 running a 360 currently. Electric fan and fuel pump.

Looks like I have a bad alternator. Battery discharged at a show, barely made it home after getting a boost. Charged the battery and seemed ok - ammeter does show discharging but centers or moves slightly positive when driving.

So I tried the remove positive lead trick I saw suggested here in another thread. Motor quit running after about 5 seconds.

So, I am guessing it needs replacing. Any input appreciated as to what alt. might work well with my car.

Thanks,

Steve

 

[TrailBeast]

Ha, you made it three weeks?
Second day I had mine the alternator died.

Get the squareback 65 amp alternator if at all possible, because they have better output at lower RPM's.
Also look to see if you have two field wires, or just one.

Notice the square area for the diodes versus the one on the left.

 

[67Dart273]

This problem could be about anything

wiring problem, meaning anything in any part of the ignition harness

or a problem in the charging line from alternator through the bulkhead, ammeter, and back

bad alternator

bad regulator

What do you mean you "removed the positive lead?"

Pull the green field wire and ground that alternator field terminal. Run the car, see if it charges, and check voltage right at the alternator output stud--the big stud/ nut connection

If this does not cause a charge condition, turn key to "run" and check for voltage at the blue field terminal at the alternator.

If no charge, most likely the alternator.

You should make an effort to learn to troubleshoot this stuff. Chryslers charging systems are one of the simplest on the planet, and are easy to learn to deal with.

1---Get yourself a service manual. If you don't want to buy one, you can download a couple for free:

[ame]http://www.abodyjoe.com/pictures/Misc.%20car%20info/70%20Dart%20Challenger%20Serv%20Man1.pdf[/ame]

http://www.mymopar.com/downloads/servicemanuals/1970_Plymouth_Service_Manual.zip

2---Get yourself a 12V test lamp, an inline spark tester, and a multimeter. Go to Radio Shack and buy a couple of bags of clip leads

 

[Dustdevl340]

This problem could be about anything

wiring problem, meaning anything in any part of the ignition harness

or a problem in the charging line from alternator through the bulkhead, ammeter, and back

bad alternator

bad regulator

What do you mean you "removed the positive lead?"

Pull the green field wire and ground that alternator field terminal. Run the car, see if it charges, and check voltage right at the alternator output stud--the big stud/ nut connection

If this does not cause a charge condition, turn key to "run" and check for voltage at the blue field terminal at the alternator.

If no charge, most likely the alternator.

You should make an effort to learn to troubleshoot this stuff. Chryslers charging systems are one of the simplest on the planet, and are easy to learn to deal with.

1---Get yourself a service manual. If you don't want to buy one, you can download a couple for free:

http://www.abodyjoe.com/pictures/Misc. car info/70 Dart Challenger Serv Man1.pdf

http://www.mymopar.com/downloads/servicemanuals/1970_Plymouth_Service_Manual.zip

2---Get yourself a 12V test lamp, an inline spark tester, and a multimeter. Go to Radio Shack and buy a couple of bags of clip leads

Took the positive clamp off the battery as per another thread.

I do have a service manual and will check - should have thought of that myself. First Mopar so I'm not that confident yet figuring things out. Expect I will get better as I go along.

Thanks for the suggestions. I will give it a try.

Steve

 

[Dustdevl340]

Ha, you made it three weeks?
Second day I had mine the alternator died.

Get the squareback 65 amp alternator if at all possible, because they have better output at lower RPM's.
Also look to see if you have two field wires, or just one.

Notice the square area for the diodes versus the one on the left.

Second day - bummer.

Thanks. I'd heard that the square back was a better alternative.

I'll try some more trouble shooting first.

Steve

 

[BillGrissom]

Took the positive clamp off the battery as per another thread.

I am surprised nobody yelled "NO!!!". That is a good way to cause big surges in your wiring harness and damage electronics. I used to test alternators that way too, in my dumF kid days.

Before I would replace an alternator, I would verify it doesn't work in-place first. Otherwise, you may be blowing a lot of money and time, and not fix the real problem. Apply 12 V across the 2 field terminals, with nothing else connected to them. If one terminal is already grounded (most round-back alternators), ground it with a jumper to be sure. With 12 V across the field (engine running), you should see a lot of current output on the car's ammeter (or install a separate big in-line ammeter). If not, maybe just worn brushes, which you can fix in the car. To go further, verify that the field draws current.

 

[Dustdevl340]

I am surprised nobody yelled "NO!!!". That is a good way to cause big surges in your wiring harness and damage electronics. I used to test alternators that way too, in my dumF kid days.

Before I would replace an alternator, I would verify it doesn't work in-place first. Otherwise, you may be blowing a lot of money and time, and not fix the real problem. Apply 12 V across the 2 field terminals, with nothing else connected to them. If one terminal is already grounded (most round-back alternators), ground it with a jumper to be sure. With 12 V across the field (engine running), you should see a lot of current output on the car's ammeter (or install a separate big in-line ammeter). If not, maybe just worn brushes, which you can fix in the car. To go further, verify that the field draws current.

Thanks, will not be trying that again.

Newbie so I have a very big learning curve ahead of me. I'm going to learn to do as much as I can, hopefully without screwing things up too much!

Steve