Alternator-Am I missing a step/

TCB · 07-12-2006, 02:15 PM

Ok,
I've searched all the postings and gained a LOT of info but I wanted to make sure I've not missed a checkpoint before I pull the alternator.
Battery light in dash is on at idle, voltage 12-12.9 volts.
At about 2000 rpm light usually goes off or at least gets a lot dimmer, voltage sometimes goes up near 14 volts.
I've tried two good batteries..
Have cleaned all ground straps, (new engine mounts installed while I was there)
Cleaned fuses.
I would gather the next step is to pull the alternator and have it tested?

Terry

Early_S_Man · 07-12-2006, 02:41 PM

Terry,

I'm not sure why you are contemplating having your alternator tested??? From the Voltage reported, your 'Zero-Ampere Speed' may be a bit higher now[normal for many, many older cars] ... but, as long as it is ~14 Volts above 2000 rpm ... that is fine, and you shouldn't have any problems with the battery staying charged. Waiting at the bank drive-up line may be a bit nerve-racking, but otherwise, fine.

TCB · 07-12-2006, 02:52 PM

Thanks Warren

Well up to the last few days the alternator light has not come on so it has had me going. I'll keep the digital voltmeter hooked up and keep an eye on it. Good advice. If I can't keep a charge, the alternator is certainly in question then..

Terry

TCB · 07-12-2006, 06:48 PM

Just went for a long drive. The alternator light goes off now around 2500 rpm, but the voltage never reaches 13 volts any more. It was down to around 11.4 volts by the time I made it home and the motor was really idling rough. I'll have a load test done on the battery tomorrow.
I did trade out batteries earlier today and there was no difference at that point although I hadn't taken it out for a spin.

rnln · 07-12-2006, 11:21 PM

My problem was opposite. It came too high.
Taking it off is more simple than you read. I did it in an hour, clean, after work. Of course I read the instruction (search function)
First, unbolt those plugs wire holder on the fan housing. There is another small bolt right near the distributor.
Second, unbolt the fan housing strap. Pull the strap and bend it out of the way.
Thrid, pull the fan/housing toward you so you can reach/see in there. Take off the plastic alternator cover, in the back of the fan housing, inside the tunel. 3 little bolts.
Next, take off all the wires, 3 total.
Pull fan/housing/alternator out.
The voltage regulator is attached to the back of the alternator. The alternator is attached to the fan housing.
Done.

TCB · 07-13-2006, 05:57 AM

That would be pretty hard on the battery. I have a digital voltage meter always on now and I'm not getting any juce out of the alternator. As I first checked it a couple days ago, it would go up over 13 volts, but then it is now not even intermittent.
I disconnected all ground straps and positive leads and cleaned them. They were actually in really good shape.
I'm going to have both batteries tested today just to make sure I don't have TWO weak batteries I'm using to test. The next step is yours, pull the alternator. It will be good to check for stuff on top of the engine anyway..
Thanks for the thoughts
Tery

Wil Ferch · 07-13-2006, 06:59 AM

For internal VR cars -- >

http://www.pelicanparts.com/techarticles/911_volt_reg_replace/911_volt_reg_replace.htm

- Wil

2.7RACER · 07-13-2006, 07:12 AM

Just a quick comment. The first step in removing the alternator is to disconnect the battery. But, you already knew that.

Wil Ferch · 07-13-2006, 07:17 AM

step #1 in my posted link ! ..........

- Wil

harold12750 · 07-13-2006, 08:07 AM

83SC, YEAH I HAD THE LIGHT ON AT LOWER RPMS, WOULD GO OFF WHILE MOVING, BUT EVENTUALLY WHEN THE TACH STARTED JUMPING AROUND ,AND THE CAR WOULDNT START ANYMORE I CHANGED OUT THE ALTERNATOR , NOW AOK. THE BRUSHES WORE DEEP GROOVES IN THE COMUTATOR, MOST CARS I EVER WORKED ON THE BRUSHES WORE DOWN

Early_S_Man · 07-13-2006, 09:59 AM

Harold,

Caps lock off, please!

Alternators don't have commutator rings ... they are properly called slip rings!

TCB · 07-13-2006, 10:49 AM

Not to be taken lightly, disconnecting the battery, good move.
It's not nearly as exciting though.

Thanks for all the input. Will, I did read your article. Thanks for taking the time to put it on. Really informative.

Wil Ferch · 07-13-2006, 01:34 PM

Info sharing....it's what we're all about ....

- Wil

911mot · 911mot's Garage

Make a mental note, draw a diagram , take a picture or whatever of the orientation of the plastic air deflector and the the positioning of the alternator in its housing before you strip it all down.

2.7RACER · 07-14-2006, 03:15 PM

Wil,
There is a mis-understanding. I was referring to rnin's post, not yours. Sorry,

Wil Ferch · 07-14-2006, 04:59 PM

No problem.. and no offense taken, Doug...

The consequences are dire...so I simply reminded others ( regardless if your remark *was* intended for me, or not)...that the essential deactivation of the battery is already mentioned as step #1 in the write-up.... no matter who reads it....

Again...no issues ...

Wil

TCB · 07-15-2006, 05:24 AM

Thanks to all the info on this forum, it took me about 50 minutes to have the alternator out of the car. Unfortunately I found a couple of bad cracks in the blades. The PO wasn't too careful with whatever work was done there. I'm going to find another fan as I don't want to put this one back in. The alternator tested out bad, no output. I'm glad I went through all the steps before pulling the alternator though. I learned a lot more about the car, plus it prompted me to put the new motor mounts in that I have had sitting around for a year.
Cheers

Goth · 07-15-2006, 07:51 AM

TCB,

I had this problem on an 84 Nissan. Light started coming on at idle and this gradually got worse over time (i.e. light brighter at idle and stayed on further up in the RPMs). When I took the alternator apart, I found the brushes were worn down to the point that they were hitting the end of there travel. At this point they were not able to contact the slip ring. I bought some new brushes for like $7 (Nissan) bucks and everything worked fine.

If you have more time than money, and your alternator spins free & tight in your hands without any noise, this would be the low budget approach.

If you just want it done, then back to plan A.

IMO: Bad voltage regulator usually static at "X" volts like zero or 15.

Hope this Helps...