datsun-roadsters
[Top] [All Lists]

Re: Charging system problems]

To: Datsun list <datsun-roadsters@autox.team.net>
Subject: Re: Charging system problems]
From: Pat Horne <pjhorne@mail.utexas.edu>
Date: Sat, 30 Jul 2005 21:27:08 -0500
Sorry I forgot to send this to the whole list.

------------------------------------------

Steve,

Your voltage reading may or may not be correct. More important than the 
actual voltage (at this point in your testing) is whether the alternator 
puts out something in the ballpark or not.

Wit the engine off, turn on your headlights. Does the ammeter go 
negative? If so, the ammeter is working. Leave the headlights on for a 
minute or so to draw some power out of the battery. Now start the 
engine, either with the headlights on or off. Does the ammeter  still 
show a discharge, or does it show a charge? It should show a charge. If 
it doesn't, then there is something wrong with the alternator, 
regulator, or wiring.

Assuming it still does not show a charge, turn the engine and headlights 
off. Check the battery voltage at the large white wire on the back of 
the alternator. There should be battery voltage on it. If so, the 
alternator output circuit is probably good. If there is no voltage, 
there is a wiring problem between the alternator and the ammeter.

Assuming there is voltage, I would check the wiring between the 
alternator and regulator, including grounds. Be sure there is a ground 
between the regulator and the engine too.

Assuming that the wiring is good, try swapping in the alternator you 
have that put out 30A and see if that gets things going. If not, it 
sounds like the regulator is not any good. You said that you replaced 
it, but was the replacement new, or out of your junk pile? Are there any 
folks around your area that have roadsters who would test your regulator 
on their car?

Let me know if this doesn't find the problem

Peace,
Pat

stebharvey@ameritech.net wrote:

Hi Group,

Can someone tell me what the alternator output should be for my 70 1600?
I had three original alternators tested. One was shot, one is putting
out 30 amps and the last is putting out 35amps. The guy at the repair
shop said that 35amps is the correct spec.

I've installed the 35 amp output unit (moved it from lower left to upper
right on the engine) and also inspected the voltage regulator. When I
removed the cover I discovered that the coils were burned out. I changed
out the regulator, replaced all of the battery cables and grounds.
Volt output with a static battery test indicates 12.8 volts. When
started, output at the battery drops down to 12.4 volts. Output at the
alternator is also 12.4 volts. The 1600/2000 service manual states that
the output should be 14.0 volts.

I've asked several  (non-roadster) people about the current output
readings and half say it's fine and half say, bad news, you have a draw
on the system and I must continue troubleshooting the problem. If
someone needs their airplane fixed (hammerslammer) I can handle that but
I'm a little light on 35 year old automobile electrical systems.

Steve Harvey
P.S. Should just chuck the old alternator and go new?






<Prev in Thread] Current Thread [Next in Thread>
  • Re: Charging system problems], Pat Horne <=