I have yet to put a meter on the battery to test this, but I just rebuilt my alternator (bearings, slip rings and a new voltage regulator) and below 4,500 RPM, it behaves just as it should: the voltage gauge on the dash reads just under 14V, and dips very slightly as you start adding electrical load.

The problem is that when I approach and then exceed 4,500 RPM, the needle goes up and starts bouncing up as high as 16V+.

This sounds like a bad voltage regulator, but I put a new one in when I rebuilt the alternator. It's a KAE, though. Is this one known to misbehave?

 

I didn't know you could get a non-bosch replacement - never heard of KAE.

Does sound like a voltage regulator. I suppose it could just need time to get broke in?

Let us know if you figure it out.

 

Vibrations or bad alt bearings could be making that grounding strap make-and-break

 

can you throw the old volt.reg in to see if it works properly?

 

Good idea! Why didn't I think of that? And I could presumably just pluck the brushes out of the new one if that solves the problem.

Bearings (at least in the alternator) are unlikely, as that's what I originally had it apart to replace. It turns quite smoothly, even with a load on the pulley. I will look carefully at the silver tab, though.

I hadn't heard of KAE, either, but it was cheap (they're an OE replacement for the Audi 4000 and several other VW-based alternators). That cheapness may well be the problem, mind you.

Do regulators need to break in?

 

[QUOTE=pontifex4;

Do regulators need to break in?[/QUOTE]

Charlie __when I had my 944 I change the voltage regulator on my alternator twice in a period of 26 years ,when I did it was replace by an oe one , they don't need any break in time that I know off ,you just slam the new one in & that it.Check the connections for loose wires .