alternator warning light

[kartone]

Help ! The last few days when starting a cold engine in my '80 GTV the alternator warning light goes on and stays on for approximately the first 10-15 minutes of driving; during this period the warning light is bright & steady and the only detectable difference is a slower blinker and wiper speed. The alternator belt is in good working order and tension is OK; the battery is an 8 months old, oversized Century. How can I check whether the alternator is doing its job, meaning generating enough italians electrons to keep the stallion prancing ?

[colcol]

Have a look at the regulator, the brushes may be worn down and are not making contact or the regulator may not be working, if possible remove regulator from back of alternator, usually held in by 2 screws, take it to an auto electrician and get them to check the length of the brushes, however if the brushes have to be replaced it is sometimes cheaper to buy a new regulator, if brushes are correct length, then have the regulator tested, new regulators are reasonbly cheap, thats always been the problems with my alternators over the years, Colin.

[Neil Choi]

With the battery fully charged, measure the voltage (with multimeter), it of course should be 12v.

With the car running (at idle or with a bit of revs), it should be generating about 14v.  If it is still 12v, then your alternator is not working properly and as Colin mentioned it could be brushes or regulator.

If your Alfa is a keeper, then better to get the alternator rebuild.

BTW how old is the alternator?

Neil

[Storm_X]

i upgraded my alternator to a 80amp and the light goes on after i give it a quick rev to 2000revs.

check the regulator and the bushes are probably worn right down.

[pep105]

All good advice, just another thing as your GTV is a 1980 model theres a possiblity the it will have an external regulator mounted on the LHS of the engine bay. GTV's (Nouva plastic bumper) from about 81/82 had the reg on the back of the alternator. Thats not to say yours may have been converted at some stage

Cheers

Pep

[kartone]

Thanks for all the tips.
The battery voltage with the engine off is 12.4, I will check it at engine idle this weekend.
Yes, my regulator is mounted on top of the LHS fender well; how can this type be tested ? 

[kartone]

Battery voltage is the same whether engine is off or on (2000RPM): 12.3V

[Neil Choi]

Think your alternator is stuffed, take alternator to an autoelec for recondition.

[colcol]

If your alternator light is on, then it means that the battery is being drained and not charged, if the volts are the same with the engine is switched as it is at 2,000 rpm, then the alternator isn't charging, if you have an old type voltage regulator, with points and relays, these are unreliable and hard to adjust, and you need a new one, but take your car to an auto electrician, it may be that the brushes have worn down and they need replacing, and thats it, i had a similar problem years ago, and the auto electrician told me its most likely the voltage regulator after i told him it was the alternator, he said replace the voltage regulator, $35 10 years ago, and if that doesn't work, then bring back the alternator and i will recondition for you so i replaced the regulator, started the car, the alternator charged, suddenly a $250 bill was a $35 bill , Colin drove home happy.

[kartone]

Is there anyway of checking the alternator output before the regulator ?

[colcol]

If you could take out the alternator out of the car and take it to an auto electrician, and they could spin it up on a alternator testing machine that will tell you if its working or not, then if it is you need to look at the regulator, if the alternator isn't working then get it recoed, Colin.

[kartone]

Will remove alternator today and sometime during the week will get it tested.
Many thanks Colin.

[kartone]

 I have been quoted by two sources for the supply of a new identical alternator ... hold on to your pants ... available ex-Germany ... AUD 835.00 ... plus ... AUD 200.00 freight 

[kartone]

What would be a fair price for an alternator to replace brushes and bearings in an alternator ?

[colcol]

Don't get a new one at that price as you are putting in new components that never wear out, get the auto electrician to recondition it, new bearings, brushes, maybe turn the communtator to remove the grooves where the brushes run, check the windings and the stator and the diodes, give it a clean, with a warranty, and that should do 150,000kls, new ones are ok if they are old stock, but beware of cheap new ones, i once knew a bloke who got FIVE and put them in his car until one worked, this is from an un-named Country, Colin.