I had the same issue some years ago.
It started with very dim battery warning light.
After that the battery was empty when the car was not ran for a week or so.
I got fed up with this and took an amp meter and measured, if there was any
current running from the batteries when the ignition was turned off.
And yes - there was some 10 milli amps running all time.
The cause?
A diode in the alternator was leaky.
As the alternator still was the original one I took it to the local car
electrics shop.
They installed a new diode pack, new brushes and brush ring, which was worn
out as well.
They also can verify, if new bearings are needed as well.
The unit is apart anyway, so replacing these won't cost much extra.
Mine never failed again and reliability always is important for such car
parts I think.
Cheers,
Hans
71 BGT
-----Oorspronkelijk bericht-----
Van: mgs-bounces@autox.team.net [mailto:mgs-bounces@autox.team.net] Namens
PaulHunt73
Verzonden: dinsdag 27 augustus 2013 9:37
Aan: Simon Matthews; MGS
Onderwerp: Re: [Mgs] Alternator? problems
Does it glow more brightly with the headlights on? That is an indication of
bad alternator diodes or bad connections.
The first thing you should do is to measure the system voltage on the brown
wire at the fusebox, with respect to earth. Ignition off should normally be
about 12.8v (unless the engine has only just been turned off when it will
probably be higher). Ignition on will drop a couple of tenths. Engine
started and running at about 2k rpm should be about 14.5v. As you start
turning things on it will drop, but with headlights, heater fan, stop lights
etc. all switched on it should still be above 12.8v.
If below that measure the voltage on the output wire of the alternator, a
thick brown, under the same conditions. If that is also below then the
alternator is faulty. If clearly above what you measured on the fusebox
brown then there are one or more bad connections between those two points.
The connections between the two brown wires and the battery cable on the
solenoid stud is a candidate for that, remove the battery earth strap for
safety before tackling these. Also measure the voltage on the brown and
white wires at the ignition switch and its multi-plug connections. Good
voltage on a brown but lower voltage on a white points to the ignition
switch.
The first link shows a late model 3-terminal alternator, although the two
large spades are linked together and are both output spades. The
standard-sized terminal is the warning light. The other two terminals were
never used on MGBs. MGBs *did* have five (69 to 71) and four (68) terminal
alternators with two plugs, and the second link, left-hand image shows the
two-plug, five terminal arrangement that a 71 would have had originally. It
depends on what you have now as to what you have to do, if you have the
three spades in a row, two large and one small like the second link, image
on the right, then the mod has already been done.
PaulH.
----- Original Message -----
> We have a '71 MGB which is having charging problems, I think. The
> ignition
> (red) light on the dashboard only goes out (well, it goes very dim)
> when cruising on the freeway.
_______________________________________________
Mgs@autox.team.net
Archive: http://www.team.net/archive
Unsubscribe: http://autox.team.net/mailman/options/mgs/h.duinhoven@planet.nl
_______________________________________________
Mgs@autox.team.net
Archive: http://www.team.net/archive
Unsubscribe: http://autox.team.net/mailman/options/mgs/mharc@autox.team.net
|