Alternator

The voltage regulator in the alternator on my GTA failed recently, over-charging at 16+ Volts. That boiled a lot of water off the battery. The first I noticed was a smell of eggs and the battery losing charge frequently.
I bought a new alternator as it was more convenient for me than an exchange rebuild of the original.
The new one has a smaller pulley, approximately 60 mm diameter, compared with 76 mm on the original.
I guess it will charge more at idle / low revs as it spins faster and the turbo engine doesn't reach high revs, so it isn't going to go ballistic fast. The smaller pulley also moves the unit a bit further from the exhaust manifold when the belt is tensioned. A slightly bigger air gap is better for reducing heat transfer....

I know the service history back to 1998. The alternator I took off was well, old, but was it the original Valeo type. I don't know.
The service record shows the voltage regulator was changed in 2001, but it could have failed & been replaced before that too.
Does anyone know the correct pulley diameter?
So I wonder if there are any advantages or disadvantages?
Nigel

Personally, I would have just changed the regulator .......... just check your alternators number against the "product description" list at the bottom of the page.

https://www.amazon.co.uk/Alternator-Vol ... 09-6419126

Apart from the regulator, the rest of the alternator is virtually bullet proof.

Thanks John,
I will get a regulator and fit it to the original as a complete spare unit. The rest of it does seem in good condition - as you say - bullet proof.

[mettersl]

This failed on my newly rebuilt GTA on the way back from Macon..fortunately not completely but enough to limit engine speed on the way home...hey 80 mph is enough for anyone..changing it took 5 minutes once off the car....
IIm with John, get the regulator and repair your old one too, just in case. The pulley diameter difference will mean ~25% more alternator revs.
I don’t know if that’s going to break anything...the voltage regulation should be fine. Let us know h9w long it lasts, it looks like they are a consumable on these cars anyway.
On mine one of the brushes had worn, rest of the alternator was fine.