TR6 TR6 Alternator Problem

[martx-5]

This is just a head's up on an alternator problem one of the members of our local club has been experiencing for about a month. The problem originally started with a dead Lucas alternator that was replaced with a rebuilt. Well, as so often happens, the rebuilt didn't work...or did it...This very patient fellow brought the rebuilt alternator to two separate independent alternator shops, and both said that the unit was fine. Put it back on the car, and nothing. We swapped the alternator out with an old one laying around and the unit is charging fine. Patient fellow brings the rebuilt unit to a THIRD rebuilder, and he says the same thing...nothing wrong with the unit.

Well, since I work for an electrical re-manufacturer, at yesterday's tech session, they dumped the problem in my lap. Oh, well, I gave it a go. Here's what I found. Refer to the picture below from Paul Rego's thread on his alternator upgrade.

You'll notice the two large terminals in the picture. The bottom one and the middle one. On all alternators of this type that I have encountered, those two terminals were always connected together internally, and both were the output terminals. Well, the rebuilt alternator did not have continuity between these two terminals. As a matter of fact, the bottom terminal in the picture seemed to have continuity to nowhere! And, that is where the wiring harness plug connected to...the bottom terminal...going nowhere. We moved the wire to the middle terminal position in the plug, and everything worked just fine.

So there you go. Sometimes both the guy saying it doesn't work and the guy saying it does work can be right...if that makes any sense...

Monday, I'll have to check with the guys at work to find out how this can happen on that Lucas rectifier.

 

[TR3driver]

Thanks for the tip, Art.

Purely as a side comment, if it were my car, I'd want to be using both of those terminals. Those quick connects just aren't big enough to carry that much current for long periods without getting hot, which leads to corrosion, which leads to more heat. IMO you'll have a more reliable setup if both terminals are actually used to carry the output current.

I've seen several of the single setups burn up. When it happened on my Stag, I converted to a bolted connection instead.