Here's a copy and paste of an e-mail that my buddy sent to one of his friends (a mechanic) for advice and I thought reading thru these steps would help you better understand what we've done to troubleshoot this problem and possibly offer some additional advice:
Recently, he was driving and noticed a sound of electrical arcing under the dash and at the same time smoke coming from the aftermarket radio which has worked fine for about 5 years (since it was installed). The radio is now inoperable but the fuses are good. By the way, he instantly disconnected the radio from its power supply during that event. He then continued to drive that same day in the rain and needed the wipers. Turned the wipers on and the wiper speed was erratic. When he turned the wipers off the motor would not park (but eventually did). Wipers work fine now. Right after that, he noticed the battery case was deformed (expanded). He also told me that prior to these events, the positive battery clamp would arc (very noticeably) when connecting it to the battery with the key off (he has a habit of disconnecting the battery when not in use).
I got involved at this point. Here are my diagnostic steps thus far:
-Visually inspected battery and verified the deformed case. Tested battery with my Midtronics analyzer and it tested bad (270 cca on a 770 cca battery).
-Replaced battery (and tested to make sure the new one is good).
-Measured voltage at the battery with the engine running (12.6 volts...not charging).
-Noticed alternator belt was very loose.
-Tightened belt. Still battery voltage (measured at the battery terminals).
-Measured voltage at positive stud on alternator...12.6 (engine running).
-Jumpered 12 volts to field terminal on alternator while checking voltage at charge stud...still battery voltage (with engine running at 1,500 rpm).
-Removed alternator and noticed it was locking up and lots of dirt falling out of the case.
-Installed reman 54 amp alternator (old alternator was 42 amp) and new mechanical voltage regulator (figured that would be a good idea).
-Still not charging.
-Full fielded once again. Instant 18 volts at battery (idle speed).
-Measured voltage at new regulator terminals with it plugged in and engine running (back probed plug):
F terminal 2.6 volts (field pulling .5 amp). I think that's normal.
2 terminal 0 volts
3 terminal 11.9 volts
4 terminal 2.8 volts
-I THINK #4 terminal is an input switched 12V (which energizes the regulator) so 2.8 volts is a problem.
-#4 wire runs thru bulk head connector at firewall and the connector was very corroded. Cleaned that connector with electrical parts cleaner, used small file to shine the male/female terminals, and blew out with compressed air. Still only 2.8 volts at #4 terminal.
-Jumpered 12 v to #4 terminal with engine running and measured 14.5 v at battery terminals (yeah that's the ticket).
-Ran a new 16ga. wire (with an inline 5 amp fuse) from a switched 12 volt terminal at the fuse box) to #4 terminal at the regulator.
-Started engine with dvom on battery terminals, measured only 13.5 volts and quickly thereafter noticed smoke coming out of regulator and the positive battery post was so hot that it burned my hand (yikes!).
-Shut off engine and disconnected battery instantly.
In hind sight, I think mechanical voltage regulators are matched to the amperage of the alternator (field winding current). I wonder if we need to find the correct regulator (assuming that's the problem), however I'm very confused as to why the positive battery post was hot to the touch (did not feel negative). I think it may be a better idea to install a modern single wire alternator (with an internal regulator obviously) and run a new "charge wire" to the positive battery cable clamp with a fuse link at the alternator charge stud. Since he already bought that 54 amp alternator, I wonder if we should install an external ELECTRONIC regulator to save money in lieu of messing around with trying to find the proper mechanical regulator.
Here some additional information that may help you provide me with some thoughts:
-Noticed ground strap was missing from firewall to block. Installed a new one.
-For a long time, the horn button would sometimes shock the operator when depressed (nice). For about the same amount of time, the brake lights would not work intermittently. These issues are currently NOT a problem. I wonder if the ground strap fixed that horn problem? Not sure whether that ground strap would fix the intermittent brake light issue (seriously doubt that). Brake light issue could show up again.
What are your thoughts on this scenario?
