alternator charging too high

[FlatBlackBurb]

the other night when i was driving my truck i noticed the lights got intensely bright and i saw the battery voltage meter jump from 13 (where it normally is) all the way to the red. i immediately pulled over for fear i might blow fuses and i went under the hood to find that the positive cable leading from the alternator to the battery was barely tightened at the alternator and was just jiggling around on the post. i tightened it up and then the meter started jumping all over the place. it would be fine for a while, then it would go forward to the red and my lights would get bright, then it would below 13 and my lights would go dim. everything is hooked up o.k. i believe. the battery cable that connects to the alternator shares a connection with a wire that plugs into the side of the alternator and thats the only connection i see on the alt.

is it time for a new alternator? i dont want to drive this truck to town because now it just stays all the way in the red.

when my battery wasnt getting charged in my '69 caddy i replaced the voltage regulator. so im wondering if my truck even has one of those or if they're a thing of the past. thanks

 

[dyeager535]

Alternator innards are what control the voltage, so something in the alternator is screwed up.

Which truck?

Sounds like it's a CS style alternator, (I believe all one wires are CS?) I have no idea what a rebuild kit runsfor one. Seeing as I just paid $90 for a CS130, and 10/12SI rebuild "kits" are $20, I'd be inclined to see what a rebuild kit for yours would cost, as I expect they are as simple to rebuild as the SI series.

 

[4X4HIGH]

Sounds like the internal regulator took a dump on you. You can either replace the regulator or just replace the whole alternator as a unit. Keep in mind that if you replace the alternator as a unit it will come with a warranty of some sort but just repairing the bad part you get no warranty.

 

[FlatBlackBurb]

hmm im more inclined to take apart my old alternator and at least try to repair it. i had to repair the one on my '69 caddy and it wasnt too bad.

oh sorry i forgot to mention its my 87 suburban

 

[dyeager535]

If it's the CS130, the manual says it's not rebuildable, but not sure why, since it comes apart. Not to mention the parts store ones aren't brand new either.

Just need to make sure the regulator assembly (or whatever they call it on the later ones) is available. "rebuild kit" from a parts store should have all the required electrical pieces.

edit: just looked up a CS130 rebuild kit on cskauto.com, and they want $45. With a "new" one from them, probably lifetime warranty, they only want around $80. It may indeed not be worth the time/effort, except for the experience. SI series rebuild kits are half that, so it's actually worth the effort.