Voltage surging on 89 740 GL!

[Jim Caldwell]

The voltage is surging very badly when the car is first started and for the
first few minutes you drive it. Does not affect engine, except you hear the
cooling fan and AC fans surging up and down---but engine RPM is not affected
noticeably. After a few minutes of driving, the problem goes away.
I guess this would have to be a bad voltage regulator? I don't know whether
the regulator in this car is internal to the alternator or external. If it
is internal, do I need to get a rebuilt alternator, or is it something that
a weekend mechanic can replace himself?

 

[Mike F]

The voltage is surging very badly when the car is first started and for the
first few minutes you drive it. Does not affect engine, except you hear the
cooling fan and AC fans surging up and down---but engine RPM is not affected
noticeably. After a few minutes of driving, the problem goes away.
I guess this would have to be a bad voltage regulator? I don't know whether
the regulator in this car is internal to the alternator or external. If it
is internal, do I need to get a rebuilt alternator, or is it something that
a weekend mechanic can replace himself?

The regulator is internal, but mounted on the outside of the
alternator. If your alternator is mounted high on the left side of the
engine you can swap it out with the alternator still in place. You
should really check the voltage at the battery while the problem is
occurring to make sure it's not a problem with the wiring.

--
Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)