alternator guage over the top

[Dire McCain]

Here's a new one for me. out of nowhere the alternator guage is off the scale on the high side...it's
reading over 18 volts? wtf? It drops when I turn on somethng like the AC...or when I am at a stop light idling...but still way closere to 18 v than 12...

Battery? Voltage regulator?

 

[OneJArpus]

regulator is bad, time for a new alternator.

 

[IJ.]

regulator is bad, time for a new alternator.

and a battery if he keeps driving it.....

 

[TomFraser]

When getting a new alternator you will probabbly end up with a reman.

Have them test it before you leave the store, autozone and pepboys had 5 bad ones, terrible quality control. I ended up getting a high amperage one off of ebay (cheaper, no core bullshit), and am happy so far.

 

[OneJArpus]

and a battery if he keeps driving it.....

Very true, be sure to have the battery tested when you replace the alt to make sure it is still good.

When getting a new alternator you will probabbly end up with a reman.

Have them test it before you leave the store, autozone and pepboys had 5 bad ones, terrible quality control. I ended up getting a high amperage one off of ebay (cheaper, no core bullshit), and am happy so far.

You can buy them new IIRC, i know of a parts store that sells new alternators & starters. The difference is great when it comes to pricing though.