Alternator/battery issue

[Bradsp8]

1975 Sport, original/stock except brake booster, headers and a headlight harness upgrade I can't remember the name of but it did help....a little, more with pulsing than brightness. 89k miles on the odometer.

Drove the Bronco about half hour last night and noticed my lights were gradually getting dimmer. Then the dash lights and speedometer were getting dimmer. Then turn signals stopped working.... but I could increase the rpm's and the turn signals would work better but not perfect, kind of slowly dimly blinking. Figured something was wrong so I drove about another mile home. Pulled into the driveway and went to back into the garage and it died. Had to push it into the garage. I was lucky I made it home and it didn't die in the middle of the road.

Does this sound like alternator died or it died a week ago and my battery just faded out slowly?

If alternator, what is my best, most simple, closest to stock alternative to replace it?

 

[B RON CO]

Hi, if this was my Bronco I would charge the battery and then check the voltage at the positive battery terminal when the engine is running. You should see @ 14 volts. If you only see 12 volts the charging system is not working and you need more tests. The main parts to check are the battery, alternator, regulator and fan belt. Good luck

 

[ared77]

Sounds like it may be your alternator to me. I had a '70 Mustang sports roof (fastback) years ago and drove it to Lexington and noticed lights getting dimmer, turn signals acting weird, etc just like your symptoms. It was the alternator. Good luck!

 

[Bradsp8]

Thanks. Battery is 8 years old so I will charge it tomorrow and test it to see if 14 volts. I may also take it and have it tested at O'Reilly's or Autozone. If battery tests good I will start trouble shooting the alternator.

My thought was if alternator was still working that I could drive around with a dead battery.....until I turned it off. Will the engine run w/o a battery if the alternator is good?

I think I remember an old trick of disconnecting the battery while running and if it cuts off then it's the alternator. Otherwise the engine would still run off the alternator, right?

 

[spap]

A battery at 8 years old is done, might even test good, but very close to the end
With the bronco running and the battery in you should see 14 volts at the terminals
I bet alternator too or both bat and alt.

 

[Bradsp8]

New battery and all is well.

Now thinking of replacing alternator just for peace of mind. Anyone with suggestions for basic, close to stock, replacement please let me know.

 

[Seventee]

If it's working I would leave it alone. Nothing saying you will get a better alternator with a replacement these days.

 

[gnpenning]

You really need to check your charge system along with making sure you have correct voltage at the right places. Don't forget to do a regulator by pass test.

Just because it's started and runs on a fully charged battery doesn't mean your problem is fixed.

 

[B RON CO]

Hi, X2 with gnpenning.
I would check the voltage at the battery. It should be @ 14 volts.
A load test with an amp reading is better, but you can't do that at home.
Don't just change parts because they are old. They are better made then the new replacement parts.
If you do end up needing an alternator or regulator you can get original style parts from most auto parts store.
Good luck

 

[charlie6976]

As I remember, you should/are able to run without the battery. Remember push start with dead battery. So if you only changed your battery, it will just run down.

 

[Rustytruck]

check the battery voltage after sitting below 12.5 volts battery sucks. 12.7 after sitting is a good battery. check battery on the posts and on the battery clamps. if voltage at the clamps is lower than the posts clean the posts and the clamps. remember battery cables have two ends both ends must be clean and tight. start the engine and check the voltage it should be over 13 volts and closer to 14 volts on startup. if your getting close to 14 volts the alternator should be fine. clean and tighten the alternator connections including the alternator mounts. alternator needs good clean ground in its mounting bolts and mounting brackets. if voltage is still low go to the voltage regulator. its mounted on the firewall above the passengers side front fender. the mounting bolts and bracket surfaces must be clean and tight for the alternator to work properly. if you have the tall square can type voltage regulator good time to replace it with the more modern electronic voltage regulator it has a lower flatter profile. Don't buy the cheapest one out there you just getting Chinese crap. buy a Motorcraft or standard products one if you can find one. check the plug in connector make sure its clean. the Bronco charging system is dirt simple and pretty reliable in its stock form other than the original mechanical voltage regulator but it is very dependent on good clean electrical connections. the whole truck is that way. it not like modern cars with sealed connectors and multiple redundant ground connections. all those original connections are 50 years old on trucks with significant corrosion.

 

[Bradsp8]

Thanks for the suggestions. Will work on it further this weekend.

 

[Jfryjfry]

I would suspect the alternator. And I have a few good batteries older than yours was. Some bad ones that were younger but yours might not have been bad.