Weird charging problems in 4kq after regulator replacement

[Luis Felipe Patiño]

Hey qlist,

after the brushes wore off on my two-year old bosch voltage regulator, I
replaced it with a Hella unit that said 14.1 V on it, about 1 month ago, on
my 90 A bosch alternator in my '87 4kq.

(Huw, you're great at this electrical stuff. Can you help me figure this
out?)

It worked at first, then did some crazy stuff, and now the voltage reads
around the 10 V mark at 1000 rpm and the alt and OXS lights flicker faintly.
If I speed up to 4000 rpm the lights dim out, but the voltage stays same.
With key on but engine off dash lights are normal and battery voltage at
console reads one LED under 12 V.

What's going on? here's the other crazy symptoms that the charging system
displayed before it got to this point after installing that regulator:

2  weeks ago if the engine reached 4000 rpm the voltage started dropping to
the 10 V mark on the console and the alt light would come on faintly, and
would not come up until the engine wound down to 1000 rpm.

I had the alternator tested by a FLAPS then, with diode and windings ok and
voltage fine, yet voltage did get low after revving up to 3000 rpm, as read
by the portable tester.

Suddenly, it wouldn't come up at all, and after turning the engine off the
oil light and buzzer came on, just as when the circuit is open (ie no
brushes, or no blue wire).

However, hours latter I still started the car, and revved the engine up, and
the alternator started charging well with normal dash lights on with engine
off. It worked fine for a week, but now the voltage is low again as I said
above.

Also, right before the brushes wore off on the old regulator, I did notice
the alt light comming up faintly at high engine speeds.

What gives? regulator? alternator? more?

This is my daily driver,
TIA for your help,

Luis