Posted by a p bloom on Thursday, January 01, 2004 at 7:52PM :
In Reply to: Alternators posted by Josh on Thursday, January 01, 2004 at 7:41PM :
Yes, I have one suggestion that may help you and others.
When alternators go bad, it is usually the diodes that fail. The diodes in most alternators are pressed into a base plate, which provides the negative connection, and the little loop of wire on the top of each diode is the positive lead.
When some rebuilders replace and re-solder the diodes, they use acid-core solder as an expedient. It burns right through any corrosion or dirt on the top lead and allows a quick operation of soldering to the stranded wire that connects the diodes.
The problem with acid- instead of resin-core solder is that in the hot environment of an engine compartment, the acid begins to eat through the wire, causing a resistance situation, which then causes more heat, etc etc etc. Sonner or later the wires corrode right off the diodes.
I have taken apart many (rebuilt) alternators that have failed, and I have determined that the acid is the cause, and have used baking soda to neutralize it, then soldered in new wires, using the correct solder.
This is just one possible reason, among many others, and as I said, it pertains only to rebuilt units. I hope this helps. apb
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