Mid9 Electrical, Alternator Question

[74cookiecutter]

I recently purchased an Alt, Fan Assembly from a fellow pelican. After installing it I found my Gen light always on???

It is the same Marchal 55amp model as was on it before so my Regulator should not be the issue.

Can an "average local" Alt shop test for Alternator or Regulator problems while they are still on the car or do I need to take the Alt off to have it bench tested?

Also having trouble getting the Fan aligned to not touch the Fan housing because when I tighten the Alt down to the Fan housing I crush the tabs on the Air diverter. Any suggestions about this?

[74cookiecutter]

bump

[Chuck Moreland]

Looks like your blue wire (idiot light) is in the wrong place. It needs to go to D+.

[74cookiecutter]

Chuck, That is the + location,
just as it came off the original.
Next idea?

[cmonref]

By this statement:

"Also having trouble getting the Fan aligned to not touch the Fan housing because when I tighten the Alt down to the Fan housing I crush the tabs on the Air diverter"

do you mean that, fully assembled, the fan blades contact the fan housing? If YES, then you have a fan housing that is from a later model 911 that has the 75 amp alternator (or higher).

If you mean that you must "draw the alternator in" when you put the six mounting nuts on the back of the alternator, then the alternator does not fit right. The alternator should fit fully down into the fan housing -- if you need to "draw it in", then you must remove some metal from the perimeter of the alternator or the inside diameter of its mounting flange until it DOES fit. The air diverter fits against the mounting flange -- again without requiring a "draw down".

Now, to your original question: if the alternator light is ON with the ignition OFF, then you have a bad positive diode. If this is true, then the alternator light MAY, or MAY NOT, be ON with the engine running.

[74cookiecutter]

Brian, Fan and housing are matched set, so that should not be my problem. They just slightly touch at bottom rt. I was also thinking the housing might be out of round...
What I really think is that I'm not tightening the nuts and washers down tight enough on the Alt mounting bolts because I'm aftraid to break any more of the Diverter tabs, which are sandwiched between the nuts and the magnesium mounting flange on the Housing. Thus the Alt is not seated completly and able to be pulled down by the Fan Belt.
Fan belt has plenty of slack in it, so overly-tight belt is not the issue.

Alt light: Comes on when key is turned halfway and stays on through all RPMs.

[cmonref]

Your alternator MUST fit into its mount fully WITHOUT the need to "draw it down" with the nuts. Fix that problem first, then you will not break any more tabs on the air diverter.

If the alternator does not fit fully into its mount, then find out where it is binding and remove enough metal so that it fits properly without having to be forced. Sanding off the old corrosion may be all that is necessary.

Brian

[74cookiecutter]

So... Sounds like I'm going to have to remove the Alt anyway but...
Can it be tested on the car?