Do I have a bad alternator?

[Mat M]

OK, I did the ZX alt. swap with the help of Arne's adapter and excellent directions.

As soon as I was able to start the car, a high-pitched squeal eminated from the engine compartment that was NOT there before the swap.

Tonight, I got the car warmed up, the squeal was not as intense, but was still present. I noticed, as I was taking the car down the driveway, that the lights would dim (maybe -30% intensity) when I hit the brakes. I looked at the ammeter and it was reading on the negative end of the scale. I tired different accessories, ie windsheild wiper, and the car nearly stalled! The headlights nearly went out, and the wipers froze about 6 inches up the windheild. I coaxed the wipers back to the off position, and thought maybe some high RPMs would help the situation.

As I was driving on the street, ~30 MPH in 3rd gear (with a 4 speed) I noticed that the headlights just got dimmer and dimmer. When I hit the brakes, the intensity almost dropped to zero.

Do I need to reswap the alternator (I have one more ZX alt)? Do places like pep boys or kragan test the alt?

TIA

[Goose52]

On the squeal - are you sure the fan belt is tight?

The other symptoms could be fan belt as well. Was the alternator you installed a fresh rebuild? How old is the battery?

[Pir0San]

I know Autozone, Kragen's, and maybe pep boys can test alternators. Usually a high pitched squeal is due to a loose belt. I tighten my belt by putting leverage against the alternator and front cover (not too much, just enough to snug it), and tighten it. Keeps it nice and tight.

[260Zed]

My vote is also on belt tension...

[Mat M]

Thanks for the input, guys!

IIRC, the fanbelt had maybe 3/8" wiggle after tightening the tension bolt on the alt. The alt is not rebuilt. I took it straight out of the 82ZX parts car I have.

This is happening all at idle: The squeal seems to come from inside the alt. It's not constant, and it seems to coincide with about every 4th rotation of the crank. It's leading me to believe there is a bad ball in the alt bearing, like it only squeals when that certain ball gets close to the top, rolling over the race, and going back down. ???

At speed, the alt is spinning with the belt, and the headlights still faded out.

I guess I need to have it tested to be sure.

[cj71z]

I just completed this, but I bought my alt from kragens in october. I had the squealing noise so I turned it off and sprayed some penetrating oil around the shaft by the from bearings and through one of the small holes on the back of the alt. The sound went away and hasn't come back for a couple hundred miles so far.

[Mat M]

I have decided to swap the alt with another ZX alt I have to see if I can replicate the symptoms and proceed from there.

I will see about rebuilding the 82ZX alt if I suddenly come into some cash.

[mlc240z]

it probably won't take a lot of cash if it's just the bearings. they're a relatively cheap fix. i used to get mine from the local auto parts store or Grainger's supply house.

it's been awhile, but they only averaged $5-$10 each and are a straightforward install. don't overpack with grease by the way.