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Discussion Starter #1
My 87 Spider stopped running after I left it idling for about 1 hour while trying to locate a coolant leak. I tried to start it, but the battery was completely dead. After a jump start, I took it to Autozone. Their diagnosis was that the battery, alternator, and diode are good, but the voltage regulator is bad.

I have noticed over the last several months that the alternator light remains lit until I rev the engine and sometimes it takes up to a minute to go off.

Also, I had a loose negative battery connection a few months ago. When it became disconnected, the car would die. I read elsewhere on the forum that the car should continue running when the battery is disconnected and this indicates a problem with the alternator.

Can anyone comment whether the Autozone diagnosis makes sense with the problems I am having?
 

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They are 'internal' and can go wrong and can be easily replaced.

I'd sooner spend 20-30$ on a new bosch internal regulator (which takes 10 minutes to R&R once you get to it - loosen the 2 screws and pull it out, brushes and all. You will need to remove top part of air cleaner box) than just go out and buy an alternator for a couple of hundred (especially one that was just checked good)......no?

One of the screws holding in the regulator, is a ground, this needs to be clean.

You can check the internal regulator on the bench, but you need a variable DC voltage supply, which you likely will not have.
 

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Yes, an '87 should be a Bosch alternator with a removable voltage regulator in the rear. No need to replace the whole alternator. You should be able to swap out the regulator without even removing the alternator, so long as you're careful with the brushes.
 

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But Mad North-Northwest
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Cool, good luck. It's pretty easy: the trick is you need to kind of angle it in and then compress the brushes (they're spring loaded) against the rotor to get the regulator in place. If you just shove it in straight or force it you can break the brushes in the regulator, which isn't good.

Practice a few times putting the old one in and out. The old one will have pretty worn brushes so it should be easy, but you can get a feel for it.
 

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But Mad North-Northwest
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Oh, and DISCONNECT THE BATTERY negative cable before doing any of this! There's +12 hot on the back of the alternator and things could get real bad real quick.
 

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bongju said:
I have noticed over the last several months that the alternator light remains lit until I rev the engine and sometimes it takes up to a minute to go off. Also, I had a loose negative battery connection a few months ago. When it became disconnected, the car would die. I read elsewhere on the forum that the car should continue running when the battery is disconnected and this indicates a problem with the alternator. Can anyone comment whether the Autozone diagnosis makes sense
I'd say it makes sense, yes. Certainly something is wrong with your charging system. The brush/regulator assembly is the cheapest part to replace, so it's probably a good place to start. You seem to have lucked into a bright guy at AutoZone - many would have recommended a whole, new alternator.

Cool, good luck. It's pretty easy: the trick is you need to kind of angle it in and then compress the brushes (they're spring loaded) against the rotor to get the regulator in place.
They are easy to install on the bench, but I can imagine that it would be more difficult with the alternator in place.

Does Autozone carry these? They are probably used on many European cars with Bosch alternators, so it wouldn't be surprising if they were available from a generic US auto parts supplier.

For what it's worth, the new part will look like:

 

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Discussion Starter #9
Thanks Tom. I ordered the adjustable voltage regulator from IAP. What voltage should I set the output to? I saw the non-adjustable version is set to 14.5 volts.
 

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But Mad North-Northwest
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Thanks Tom. I ordered the adjustable voltage regulator from IAP. What voltage should I set the output to? I saw the non-adjustable version is set to 14.5 volts.
That seems optimistic: I think the Bosch ones are fixed at 13.8 or something. I'm not sure what IAP is shipping these days, though.

I got the adjustable one from IAP. It was operating about 14.2 as received which is pretty good, so I didn't mess with it. Some details here:

http://www.alfabb.com/bb/forums/spider-1966-up/225066-adjustable-voltage-regulator-testing.html

Note that that's 14.2 at the junction box in the engine bay. The dash gauge will read lower since that's got additional voltage drops from the switch and wiring going to it. You don't want to go too high at the junction box, though, as you risk overcharging the battery or blowing components.
 

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I have had an IAP adjustable regulator that worked fine but there has been some recent discussion regarding high failure rates of these things.
 

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I have had an IAP adjustable regulator that worked fine but there has been some recent discussion regarding high failure rates of these things.
Yea, I recalled that too when I read that bongju had ordered the adjustable version. Non-adjustable is what the factory delivered and those seem to work just fine.
 

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I just went through this a few weeks ago, right after buying my Alfa. The alt. was only putting out a little over 12V, so I went to my local auto electric shop and picked up an adjustable VR from them. Way cheaper than IAP.

These are fairly easy to put in- just watch and feel how the old comes out. It's a Bosch alternator, so it's pretty standard...I wonder why they are so much online?!
 

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Discussion Starter #15
I got the voltage regulator installed and I am getting 13.7 volts out of the alternator. I didn't try to adjust the output. The car now continues running when I disconnect the battery.

Thanks spiderserie4 and gubi for the great installation instructions.
 

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Variable voltage regulator

If anyone is still looking at this thread:

I just replaced the regulator in my '87 with a $15.50 adjustable one from Ebay. Being a very easy swap I figured it was worth a try.

The one I took out (together with some acorns and dried leaves and stuff that had jammed in the rear cover) was already not original or adjustable but I have no way or knowing how long it's been there. The brushes looked ok but I replaced it based on the fact that my voltage has been dropping slowly over time and at higher temps, to the point where I had to choose between wipers and headlamps.

After the new regulator, I can run lights, wipers, my AC full blast, and even operate a window without even a flicker from the idiot light. I even did some highway time to make sure that the voltage didn't drop like before and no problems.

My wipers and windows are faster and my headlamps are slightly brighter as well. I didn't bother adjusting or even checking the output but I think it was supposed to be 14.5 out of the box.

The worst issue I can foresee is the regulator itself crapping out. If my headlamps blow a week or a month sooner, so be it.

If I don't check back here it's either because there are no issues or because the car exploded with me in it.
 

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Checking the voltage output is a necessary step when you install an adjustable regulator. Don't trust the preset.
 

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This is just a guess on my part, but I am thinking that the car dieing with the battery suddenly becoming disconnected is absolutely correct since the EFI computer must have battery ground to function at all. Cars runing after the battery being disconnected refers to generator equiped cars only and is really ancient technology, like the manual spark advance on the Model T Ford.

I am also think that accidently disconnecting the battery could cause serious electrical problems on modern EFI and computerized cabin control cars. Something to be avoided at all costs.

But maybe Ed Prytherch (Alfaparticle) will jump in here and give us the final say since he is an electrical engineer as well as a highly qualified Alfa guy.

What say you, Ed?
 
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