Alternator repair

[Tony Radford]

The fans were running constantly. The alternator kicks in a 3k alternator RPMs. Should be pretty low in the engine RPMs looking at the pulley ratio. Something has happened. It jumped from zero to about 40 amps on the meter and back to zero in a second. The grounds look solid and I don't see any shorts.

[patrickt]

Originally Posted by Tony Radford

It jumped from zero to about 40 amps on the meter and back to zero in a second. The grounds look solid and I don't see any shorts.

If you just start it up in the driveway, and rev it to 3000 and hold it there, does the ammeter needle move around like that? What it should do is move to a decent charge condition, but then ease back to just above zero after it charges up the battery (which doesn't take very long, usually). It should be nice and smooth except for the moment that a large load comes on (like the fans), and then you might see a quick swing to the negative but it should immediately go back to where it was before the swing (or slighly less since there's an increased load).