MG Car Repair: MG Problem, jumper cables, jumper wire

Question
Hello Howard,
I accidentally jumped my MG TD (positive ground) with the jumper cables backwards. I got the car started and the voltage meter is pointing negative. I am assuming I need to re-polarize the generator or the voltage regulator?

Answer
Hi Marcus,
That is possible or you just damaged some wiring. You can test the generator to see if it was polarized in the wrong direction by removing the belt and make a jumper wire from a heavy gauge wire (16 ga.) with a pig tail to connect the field (small post on the generator) to the large post ("D" dynamo) and connect the heavy 16 ga. wire to the large post with the pig tail connecting the large wire to the small post too. Then take the other end and touch it to the (-)negative post of the battery while the (+) positive post is connected to ground. The generator will run like a slow electric motor with the belt off. Note the direction the shaft turns. If it rotates the same direction as the engine normally turns (clockwise as you face it from the front) then the generator has not been polarized wrong. If it rotates counter clockwise than you need to re-polarize the generator. A regulator does not need to be polarized.
To polarize the generator go to my web site and read my tech tip on how to do it. http://mg-tri-jag.net/tech1.htm
If the generator did turn in the correct direction then you need to check all the wires on the regulator and confirm that they do make contact with each place they are suppose to as per your wiring diagram. If you don't have a diagram, let me know and I will put one up on my web site for you to copy.
Howard