Hi, I have a 1987 325 with 277K on it and today the car stalled out at a
light. Before that the anti-lock brake light came on then the oil light.
It wouldn't turn over when I tried to restart. So I got a jump and after 5
minutes charging, it started right up. After about ten minutes of driving,
the indicator lights started coming back on and it died again. Finally got
it home and immediately changed the battery (it was over 5 years old and
needed repalcing anyway). Now it seesm fine (after 45 minutes of driving),
but every now and then the brake light, and charge light blink on when I
slow down hard. Also we checked the voltage across the battery when idling
and at 2000 RPM. It was steady at 12.4 volts which seems low. I think its
the alternator or the regulator, but not sure which. Any suggestions?
I think it is the alternator brushes are worn out. I believe the
brushes are in a "pack" that contains the regulator so replacing them
will take care of the situation.
As an aside, I recently have had the same condition on my '88 735. I
replaced the brushes and it seemed fine but now, less than two weeks
later it looks like the problem has re-surfaced.
My guess is the alternator bearing is wobbly which is causing the brush
to commutator connection to wear prematurely. My next step is a new
alternator unless someone suggests an alternative.
Good luck with yours, Bob
You have a problem - it should be circa 14 volts.
First thing to check is the actual charge warning light. Is this on with
the engine stopped, but the ignition on? On some designs this supplies the
field exciting current, and if the bulb blows etc stops the alternator
Now check all the connections to the alternator are clean and secure.
Next step involves removal. You need to remove the regulator and check
the brushes. If these are free and have plenty life left, it's most likely
the regulator which can be bought as a spare. Next possibility is the
diode pack which again can be replaced although that needs soldering
Least likely is a failed winding.
Alternators are fundamentally so long lived and reliable that the easy
way out is an exchange unit - non dealer ones are often very good value
and of course should be warranted. It's near impossible to check all the
various bits without expensive test equipment so fixing your own is a
matter of guesswork and substitution.
*The modem is the message *
Dave Plowman email@example.com London SW
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