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Is the alternator my problem?


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74 seems to stay charged and no battery problems, but the red light on my dash  gauge cluster stays on, wipers are slow, and headlights are dim. I checked the battery and when running it reads only 11.5v.  Should it be closer to 14v if charging properly?  I figured if I revel the motor or got the rpms up steady , the lights and wipers would pick up, but they don’t.





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A good battery at 60F should read about 12.6v. Generally, a charging system needs 'about' 2 extra volts to 'push' a charge into it so 14.0 to 14.5v is about right when running. Assume for now that the battery does not need replacing or the voltage regulator or the alternator as this can get expensive.


What you can do is clean the battery posts and clamps and and make sure they are tightened on. If the clamps are old and dodgy, replace them. Next check the negative cable where it bolts to the head behind the fuel pump. Is it clean and tight? Now the positive cable on the starter lug... is it clean in good condition and snug?


Now look at the two wire push on plastic plug in the back of the alternator. Is it clean, in good condition and not loose.


Last. There should be a black wire from the battery negative cable to one of the bolts that hold the voltage regulator onto the fender. This grounds both and is very important. What can often happen is that owners replace the cable but the new one does not have the extra wire for grounding the body. If this ground is missing you can easily enough make your own and run it from any good and easy to get at bolt on the (grounded) engine and run it to something similar on the sheet metal body. Use a 10 or 12 gauge piece of wire and leave some slack for engine movement. Make sure the voltage regulator is firmly grounded.


Try these suggestions and report back . If no luck we'll have to look at the 'Big Three'

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