350 alternater replacement trouble

[scremineagle]

Have read recent post on this subject but still confused. Just replaced mine on 1966 350 & charged for a short time but now won't charge. Have a 2 wire diode hooked one to alternater other to wire that leads back to the switch. any ideas what is wrong?

[kilohertz]

I read your post in the other thread and I think you may have the diode in backwards. Should allow current into the ALT, but not out. If it has a white band on it, that should be closest to the ALT terminal.

If you can, post a pic of the diode for us.

Here's a pic I found that is better than mine.

[scremineagle]

Thanks will try turn diode. So if other wire does;nt go back to the switch where on the starter should i connect it?

[kilohertz]

I reread your first post and found a better picture. See above post. If you have mechanical fuel shutdown, you can try it without diode as you have a means to shut off fuel with the lever. If it is solenoid fuel shutoff, then you will need the diode.

Good luck.

[jtrichard]

Thanks will try turn diode. So if other wire does;nt go back to the switch where on the starter should i connect it?

IF you have an AMP meter then the main wire goes to it .....IF no meter the the main wire goes to the POS batt cable on the starter

[MarkW]

When I did mine I did not have to use the diode, I just hooked it to the earlier wiring that energized with the switch. The ONLY reason that diode is there is if it is wired directly into the ignition circuit. If it is then what happens is that wire generates charging voltage when the alternator is spinning, so if you will not be able to shut the engine off.

Anyway, if it charged when it was first installed but doesn't now either-
1) the diode burnt out
2) the alt is broken for whatever reason
3) The alt is actually charging but the wire to the battery is broken/bad connection (check the ammeter for starters)
4) the belt is loose

Pretty much going to be one of those 4 things. So:
1) check voltage at the energizing wire (wire with diode) You should have voltage at the alt with the ignition key on.
2) check voltage at the output terminal on the alt. Check first when off and then with engine running. If you have battery voltage but it does not go up with the engine running check belt tension.

If belt tension is good and both wires to the alt work, the alt is most likely bad. Take it to NAPA or Autozone, etc to have it tested.