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Electric problem / burned alternator Riviera 67


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Hi all. Last weekend my alternator started to burn while driving. It was 6 months old. I got it replaced under warranty, but when I installed the new one and started the car, I saw that the ammeter directly goes right  (O)

 

Has someone got an idea where  the problem can come from

 

 

 

 

 

211513672_10165589194660061_284972572676651446_n.jpg

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Stuck regulator?  What is the condition of the battery?  If it has been overcharging the battery electrolyte level could be too low.

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I didn't have the time  to check, but I need to have a look at the regulator. On the diagram, it is possibly the only thing that could cause this.

I have been looking to replace it by a "modern" transistorized one,  but I didn't find a compatible model with the 67 Riv.

 

I guess this one is an electronic one, but it is out of stock:

https://www.rockauto.com/en/moreinfo.php?pk=936126&cc=1319059&pt=4884&jsn=9

 

I had found also that model, that fits lot of GM cars, but seems not compatible with 67 Riv

 

https://www.tuffstuffperformance.com/i-26729291-alternator-replacement-voltage-regulator-for-alternator-pn7102-10dn-7635.html

 

Has someone got a reference to share?

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You may be able to fix the one you have if the issue is a stuck contact.  You can use a small file (as used for distributor points) to clean-up the contacts.  That may get you going again while looking for a replacement.

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Try Autozone part number VR715. Worked on my '65, it is electronic and looks like the old style regulator, plus it fixed the overcharging that the new Napa regulator was doing.

 

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Posted (edited)

So I just checked the regulator.

It seem there were an electric arc sticking some contacts.

I cleaned it with a file and I put it back in place, but not electrically plugged

I started the engine and the weird thing produces when I plug the regulator: the belt whistles on the pulley, as if the alternator acted as an electro-brake, and the rpm goes down

I unplugged the regulator directly.

I still don't know if the problem comes from the regulator, or if I have a bad ground somewhere, I 'll have to test the wiring for continuity.

 

Have you already seen this happening?

image.png

Edited by Mister Fab (see edit history)
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Also make sure it’s not the alternator that’s whistling. I once installed a new one that “whistled”.

I mistakenly thought it was a belt.


I wouldn’t trust a new electronic regulator - low quality. I believe the old styles are still available just have to look more….

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35 minutes ago, PWB said:

Also make sure it’s not the alternator that’s whistling. I once installed a new one that “whistled”.

I mistakenly thought it was a belt.


I wouldn’t trust a new electronic regulator - low quality. I believe the old styles are still available just have to look more….

I am sure the alternator is not whistling.

It only whistles when I plug the regulator back, it looks that it acts like a electric motor going in opposition to the engine rotation, that's why the belt whistles.

 

Last week, the day my previous alternator burned, I heard whistling when I took the car out of the garage. I thought the belt was loose so I tightened it  before my ride, and five minutes later, the alternator burned with smoke and flames

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2 minutes ago, Mister Fab said:

I am sure the alternator is not whistling.

It only whistles when I plug the regulator back, it looks that it acts like a electric motor going in opposition to the engine rotation, that's why the belt whistles.

 

Last week, the day my previous alternator burned, I heard whistling when I took the car out of the garage. I thought the belt was loose so I tightened it  before my ride, and five minutes later, the alternator burned with smoke and flames

Long shot,  have you reversed polarity of battery?

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5 hours ago, jframe said:

Try Autozone part number VR715. Worked on my '65, it is electronic and looks like the old style regulator, plus it fixed the overcharging that the new Napa regulator was doing.

 

 

Not for 67 either...

 

image.png.59f1e837b11515ff865fe3b5703633e1.png

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Just now, TexasJohn55 said:

Long shot,  have you reversed polarity of battery?

Not, I never reversed the polarity. I have good mechanical and electrical skills, but I really don't understand how this happened. Sorry for my english, but what "long shot" means? short circuit?

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Posted (edited)
3 minutes ago, Mister Fab said:

Not, I never reversed the polarity. I have good mechanical and electrical skills, but I really don't understand how this happened. Sorry for my english, but what "long shot" means? short circuit?

"long shot" : very unlikely and improbable.    ( "Wild ass guess" ) "WAG"

Edited by TexasJohn55 (see edit history)
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Posted (edited)

The alternator that burned up most likely shorted internally. There is a good possibility nothing else is wrong.

 

An alternator has no current regulator because it self regulates. The design of the stator winding limits the maximum current.

 

I don't know exactly what would happen if there were a dead short to ground in the charging circuit wiring. My guess is the alternator would charge happily at it's maximum rating and not really even get that hot. It might overheat and melt the car's wiring harness, or open a fusible link if there is one. I don't think the alternator would smoke.

 

Sparking at the points in the regulator is normal.

 

Slowing the engine down when you plug the regulator in is normal too. It is charging. It takes horsepower to charge a battery with an alternator.

 

Squealing is probably the belt, and happening because the alternator is charging really hard, and maybe the belt is a little glazed or a little loose.

 

What I would do next is fully charge the battery with a battery charger, and then try again. If the battery is low the alternator will charge harder than normal. A fully charged battery should make it calm down.

 

If with a fully charged battery it still charges like crazy when you plug the regulator in, some test equipment is going to be necessary. Do you have a multimeter?

 

 

 

Edited by Bloo (see edit history)
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21 hours ago, Mister Fab said:

 

Not for 67 either...

 

image.png.59f1e837b11515ff865fe3b5703633e1.png

I have a '67 Riviera and replaced the original regulator with a solid state unit from JC Whitney some 30 years ago, and it's worked fine all this time.

Note: our ('66 & '67) regulator is a "generic" GM (1963-1970) unit fit for those same GM Alternator applications, even though sellers parts indexes don't reflect it.  It doesn't matter whether or not the car is factory equipped with an ammeter; the Blue & Pink wires at the connector plug is what matters. FYI

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