Originally Posted By: BrocLuno
Also, please, please add a good new ground from the negative post of the battery to the alternator mount, or somewhere close. The alternator must see a real "0" to know what it is supposed to do ...
One of the problems of all aging equipment is the ground side. On the Pos side it has voltage to move things. On the ground side it has no voltage, but still must move the same current back to source. As time goes by and water does its thing, all those old connections on the ground side build up slight corrosion which makes each a semi-conductor. Then the current that must flow home will develop enough "voltage" to get the current through the connection. The added resistance means that things like the voltage regulator will not see battery negative as zero. They may see ground as a volt or two higher. This can lead to strange situations ...
The new grounds need to be crimped and soldered which will prevent future crevice corrosion. I use at least #8 AGW stranded wire. On older vehicles I always add one from the engine to the firewall to help with gauges and such. One from the bat neg ( - ) to the radiator support so the lights are brighter. And for sure, one to the alternator. Puts the whole system on an even reliable ground. Amazing how much better things run
The big battery neg cable was almost always just crimped and it has developed "crevice corrosion" in the years it's been on the road. And it's never been cleaned and lubed on the connection to the block ... So even if you clean the bolt and the cable eye, it will still be slightly off. The new added grounds will help. The big cable can take the starter load, but the new cables will take the running loads and keep everything nice and equal
Yes all the basics need to be done. I had intermittent no starts on the tractor last week and did a load test on the battery and further testing found the problem to be corroded battery cables where the fit into the terminal connectors. That actually is a common problem.