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Alternator hack calling McGyver!!!


New Member
Sep 8, 2014
First let clarify that I live in Nicaragua, and finding original replacement parts is next to impossible. I have what we believe is a 1965 FJ 40 with a 2f motor out of a '72. I am looking for a creative solution to my alternator issues. After several short lived rebuilds the alternator that had been McGyvered into the car from the previous owners, my mechanic thought he found a solution. He found a new Nissan alternator that seemed to fit. A slight modification of the original pulley and it seemed to be working. The issue is, at idle I am only getting 12.80V and it seems to peak out 13.7v. He is convinced it is because the pulley diameter, and we can simply go down in size. I am concerned that the new alternator with internal voltage control is also designed to hook up to a car with an ECU, and without it, it is not correcting the voltage output. When I turn on the lights, the voltage drops to 12.8 or lower, and the alternator does not seem to compensate for the load. Any suggestions how to make this alternator work? Anyone planning on a road trip to Nicaragua willing to bring down a load of parts?!!


Well-Known Member
Nov 27, 2010
Do you mean at tickover the voltage drops, or when you are driving?

As to whether the Nissan part has a voltage regulator - is there a part number on it, or what did it come off?

Pulley diameter will make a difference - if the pulley on the alternator is larger it will turn the centre spindle less, which may have an impact.



Well-Known Member
Feb 25, 2014
Country Flag
Hi there

yes you have a problem, I would say if it is charging then the pulley size is not the issue if you can't get 14.4v when you rev the hell out of her. I think your new alternator might just be faulty or need an ECU. If there are Nissans out there can you get the same alternator off a running Nissan after you take a strong voltage reading of 14.4,,this is what i would do next.

also where are you taking the voltage readings??? off the back of the alternator or somewhere else?