I need to start this thread to continue my observations.

I checked the connector that had spliced in only one wire. The red appears to be original to the harness. The “field”, brown wire is spliced into a black wire. More tracing needs to be done on it.

I found the output to be 19.2 volts on Monday. I was concerned because the alternator was very hot and smoked a little. Today I got to check with another Multi-meter. Same 19.2 V. We pulled out the field/sensor wire connector and still had 19.2 V. Then we shut off the engine and restarted with the connector unplugged. That reading was 17.9 V. This I’m told is bad for the battery. And can’t be good on 51 year old wiring. Also with this alternator the Water Temperature gauge reads high, like 210*F to 220*F. Checked with no touch thermometer gun at around 150*F to 180*F. With the connector removed the Temp gauge returns to normal readings around 180*F.

Tomorrow I get a replacement alternator. See where this goes….

Steve O.

 

Sounds like the voltage regulator has failed. It's part of a standard rebuild kit. perhaps just put a kit through the Alternator you already have.

 

It sounds like the VR has failed. Depending upon the year of the car, the VR may be internal (inside the alt.) or external (on the radiator mount. If internal, pull the alt. and have it tested at your local auto parts store. Jerry

 

The internal voltage regulators are very inexpensive and easy to replace, honestly the whole alternator rebuild kit is cheap with quality name brand parts from napa. All you need is a screw driver and 2 paperclips as far as tools

 

I hope that you did not have any electronics connected to the battery while running that high of a voltage. Most common electronics would get damaged by voltages that high. I would certainly open the battery cells up and be sure that you have enough electrolyte inside of them. I have seen high voltages out of alternators when the electrolyte is very low or virtually gone or you have a bad connection at the battery itself. If it is a standard Flooded lead Acid battery the higher voltage would probably be okay for a short time period without any damage. If you are using a Sealed battery or an Absorbed Glass Mat battery your battery could possibly have been damaged. Standard old fashioned FLA batteries can take a lot of abuse and keep on ticking, the newer technologies are not always so forgiving.

After replacing or rebuilding your alternator watch the open circuit voltage of the battery and see if it stays in the 12.2-12.6 range when fully charged. My favorite test for a battery is to use a Multi-meter with "Min-Max" functions and connect the meter's leads to the battery and have it monitoring the voltage with the Min-Max mode on. Then crank the engine up and check to see how low the battery went while starting the engine. Anything below 10.5 volts the battery is either damaged or not being charged properly.

If the alternator is the original to your Corvette I would suggest you follow the advice above and buy yourself a good rebuild kit. The quality of the rebuilt alternators today is questionable unless you go to a reputable company who gives you a warranty. I am using an internally regulated 125 amp alternator in place of the 63 amp alternator that came on my 1968 C3 so I removed the external regulator that the 1968 C3's used. If you still have an external regulator then the job fixing your problems would be much easier. Like the posts above suggest the older alternators are not very hard to rebuild and that can save you quite a bit of money. The hardest part I have seen when rebuilding an alternator is getting the old bearings out and the new ones in place. Having a hydraulic press makes that job a whole lot easier.

 

I'm having difficulty understanding the "The “field”, brown wire is spliced into a black wire" part. But before condemning the voltage regulator the red, #2 voltage sensing wire should be checked for battery voltage.

 

I
Peterbuilt posted this pic. Brown wire is Field #1. Crap…now I need to look at what’s there to be sure of the order.

I exchanged over voltage alternator at Auto Zone. Had them run it on the Checking machine. Pass there with voltage range of 12-16 Volts.

Checked output on car and found 14.2 V when running. Temperature gauge now reads normally. I changed alternator to try to eliminate a light squealing noise. That’s not it.

Steve O.

 

So the original alternator tested good and the replacement alternator is working correctly? The replacement alternator is probably a one wire variant type.

 

I'm going to guess something is bubbaed up with your cars alternator or ammeter wiring.

 

I have a “chirp-chirp” noise with the motor up to temp and running a few miles. Thought it might be a worn rocker ball. Changed rockers, no luck. Pulled alt belt and spun it and I could hear a maybe rub. Bought an AutoZone reman, then the high voltage problem started. In Pawpaw’s post “Alternator Problems”, mention was made to reversed wiring causing voltage overage. My wiring is “bubba-ed” at the alternator”, so I was concerned that was the cause of the voltage problem. But with the second replacement alternator, the output voltage is 14.2- OK. The”chirp-chirp” noise is still there.

To add to the bubba list, I looked thru the AIM for alternator brackets. I have determined the PO has the wrong style exhaust manifold and rigged brackets holding the alternator. I may need to clean up that rat’s nest when I install the Borgeson PS.

No end in sight for fun with this Vette…….

Steve O.