Alternator

1971 MG MGB
150,000 MILES
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LYNN KNELLER
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My car listed above has a twelve volt battery, so I believe the alternator has been modified. I also believe that the alternator has failed. But I do not know what alternator to order to replace.
Nov 6, 2017 at 6:34 PM
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CARADIODOC
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What is the rest of the story? I cannot quickly find a source for the generator, but your starter motor is listed as a twelve volt unit. Why do you think something was modified?

What tests have you done on the charging system and what were the results? Around this time period, most generators used a separate voltage regulator. There is usually a way to bypass it to determine which part is bad. The most common failure for the generator is the internal brushes, and those can be replaced separately. An internal diode can fail too, but you would still get one third of the normal maximum output current. Diodes are usually too difficult to replace yourself. For that, look for a starter/generator re-builder in your area. Every larger city has at least one.
Nov 6, 2017 at 7:23 PM