Last Saturday I drove my '66 roadster to Cars & Coffee and had a great time. The car ran perfect on the way. Things went downhill fast when I tried to leave 2 hours later . . . the car barely cranked for a few seconds, and then I got the dreaded "clicking" sound of a dead battery. Had a few friends push me out of my space and drifted downhill for @ 75 feet and was able to pop it in gear and get it started. It ran great all the way home - but wouldn't start again when I pulled it into the garage.

I promptly put it back on my CTEK charger (which my car is usually ishooked up to) and recharged the battery most of the day on Saturday. I unplugged the charger Sunday morning and took a reading with my multimeter on the 2 battery posts . . . 12.6 volts - things looked good. At that point, a few buddies suggested I should have the alternator looked at. I took my alternator to a reputable rebuilder locally on Monday - and picked up my rebuilt alternator Tuesday. The shop ststed that they had to replace 2 diodes and replace the positive terminal which was loose.

I had a chance to re-install the rebuilt alternator this afternoon and recheck everything. Without the car running, I still get 12.6 volts at the battery terminals. With the car running, I also checked the reading on the 2 terminals of the alternator - I still only get 12.6 volts . . . shouldn't I get around 14.2 volts @ the alternator? Should I assume the alternator is not working correctly? What's the next step?

Thanks for the help!

Tom

 

Have you tried checking the voltage at the battery terminals with engine running?

 

. . . yes! . . . still 12.6 volts!

 

i had a similar issue on my 65 and it turned out to be loose battery cable connections which resulted in a high resistance situation at the battery lug. The accessories all worked but the solenoid would not close and energize the starter.

 

I agree the voltage should be more than 12.6. Since you got 12.6 volts out of a fully charged battery and 12.6 your voltmeter is reading correctly. If it was mine I would remove the alternator and have it tested. I never leave the parts store after buying a new or rebuilt alternator without having them test it.

 

Take it back and actually see when they put it on the machine that it is charging as required. IF it does...then you have an issue in your car wiring ...simple as that.

I have run into wiring where the large 10 gauge red wire that gets attached to the backside of the alternator and numerous broken strands in it ...and thus....is not going to allow it to work correctly.

CLEAN connections are IMPERATIVE....ESPECIALLY as the battery as previously stated. And this also means any terminals that slide onto other terminals NEED TO have a good grip contact also.

I would personally/professionally like to see at least 13.4 volts.

DUB

 

Thanks to all who responded so far! While I'll say that my mechanical skills are pretty well developed . . . my electrical skills? . . . not so much! So . . .be gentle guys!

Dub . . . the more I look at this - the more I'm thinking it's all wiring related - specifically the wiring to the voltage regulator. Pasted below is a photo I just took of the alternator/voltage regulator (with the tape removed to trace the wires). Notice anything missing? . . . like maybe a 4th RED wire going into the empty slot in the voltage regulator? My laminated wiring diagrams clearly show a red wire in that slot . . . where mine went I have no idea! The diagram shows that red wire should go to the horn relay? Correct?

 

Correct!




.

 

. . . can anyone tell me what gauge RED wire I need for this? . . . I think the diagram says "20" gauge? Is this the correct size? Thanks!

Tom

 

I don't know the exact wire size, but when completed, put a rubber boot on the red wire connection off the alt. Seeing it naked makes me nervous. Jerry

 

It's 20 gauge to the 'junction', then 14 gauge to the horn relay.




.

 

Buns,

I stripped away all of the tape - and this is what I found . . . is this the "junction" you refer to? As you can see - there is a 3rd wire missing. My buddies are suggesting I get a whole new engine harness - and I'm beginning to agree that this might be the very best way to resolve this issue!



Tom

 

if you find you do have the 20 ga wire missing from the voltage regulator to the junction (which begs the question, "where did it go"), simply replace the wire... no need to install a new harness
Bill

 

Thanks Bill. So . . . the metal crimpted piece in the middle of the 4 red wires in my photo is the "junction"? . . . correct? All I need to do is replace that piece, and insert the 20 gauge wire in the forward side and plug that into the voltage regulator?

Tom

 

theoretically, YES; if the red wire to the regulator is actually missing. check the regulator to see if there is a wire on the correct terminal and, if there is, see where it goes...
Bill

 

What does the rest of the engine wiring harness look like and how old is the harness? For a few hundred dollars and an afternoon, it might be the best investment you make in your car.

 

Tom and I talked today about all this. It puzzles me how it all got this way and only created a problem in the last 2-3 weeks. The wire just didn't disappear! He said it's the original harness. I'm sold on putting in a new engine harness. Electrical gremlins are not our best friend on these cars. Dennis

 

Did anyone look at a 1966 wiring diagram just to double check it's correctness, it could not work and then not work because of this, the wire just did not disappear.

If it's not correct either find the modification and repair it or replace the engine harness.

 

FIXED IT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!



Cut the old junction apart and put everything back together with the new 20 gauge red wire to the voltage regulator . . . and I now have a reading of 14.4 at the post of the alternator with the car running! Now that feels good!

 

EXCELLENT... (and you saved the cost of a new harness....)

Bill