Alternator?
 

I think that my alternator is not charging, but dont want to spend the money without confirmation from the forum first.

'85, 3.2 Targa
Voltage at battery with ignition off is 12.35-12.47V
Voltage at battery with engine started drops to 12.15V

The car has a fresh battery (it has gone through several), but the intial charge lasted about a week before it would not start. I did fully charge the battery prior to the test results above. As I said, the car has gone through several batteries mostly as it is still a "project" and is driven infrequently, but the car has not seemed to charge well.

The dash light has never come on...possibly the bulb?

Are there any other test I should perform or man-up and buy the altenator?
I understand from other threads that I should be looking for 13-14V when the car is running.

High 13s and steady as a rock. + - a few hundreths.

If you have AAA service, they will come out and check out your system and give you a print out on want the issue is.

But from what you wrote it sure sounds like the alternator. The other sign is after you start and drive around the battery charge start to drop so low that it will stall the car. The sparks and other electronics will drain the battery if not being re-charged by the alternator.

Jim

If the dash light does not come on then the system will never charge. Carefully pry out the oil pressure gauge and check the bulb.

You should be seeing higher voltage, clearly the system is not charging. With the key on and engine off the bulb must be brightly glowing. Search here for "blue wire" for more info.

what RPM did you check that at?

as for "pulling" the gauges like everyone does....

I "pushed" mine from the outside (trunk) - its a tight arm squeeze but easy as pie (just push far enough to get a hold of it from the inside)

I checked it at idle (about 1200RPM)

The light does not come on key on engine off?

too low - check your Bentley

and is your idle at 1200?? that's too high

:p

I just went through alternator problems in my 82.
In short, the tach went wild, indicating over charging (ie bad alternator)
But that was short duration, then I got no alt light and no charging.

I replaced the voltage regulator, which got me to the point that the alt light came on indicating no charging......

So I took the alternator to specialist shop, they tested it and no charging, so I had it rebuilt.

This is what I should have done in the first place, and my suggestion to you :).

Jay

Yes, idle is at 1200...and the light is never on (not even with key in on position with other dash lights on) - that is why I suspected the dash bulb might be out. I assumed that no dash light on a car this old would not necessarily indicate that all was good with my alternator. The fact that voltage at battery was low and battery did not hold charge make me think alternator is bad. I will seek an alternator shop locally in Dallas. If anyone has trusted shop here then please sound off.

the current to excite the field during start up comes through that light bulb. If that does not happen it does not work.