Alternator Arcing??

[DustyR/T]

Ok, well I was on vacation driving to Massachusetts and when I was passing through Washington DC I noticed the gauge wasn't reading correctly. When with my underdrive pulley @ idle it shouldn't show full charge. So I popped the hood to take a look and when I gave it gas it arced from the alternator case to the strut tower brace. AutoZone said it passed but I had them swap it anyways. Wonderin if anyone else has had this problem.

[anonymous_user]

Sounds like a bad ground at the alt. Pretty common. I run an additional heavy gauge ground wire from the alt - post to either the battery - or to the engine block.

[DustyR/T]

Correct me if I'm wrong, but the alternators primary ground is the case. A secondary ground wouldn't hurt anything I'm sure, but the case should provide more than enough ground for it. It was arcing upwards towards the strut tower brace. It is a 3.0 engine.

[charger R/T]

ok your saying the positive terminal of the alternator was arching to your brace correct? How much gap is between the brace and stud? Was it raining at the time? have you checked voltage at your battery and alternator with a volt meter after this happened? Is the alternator solid mount or rubber bushed? Are the engine to battery, battery to body, and body to engine grounds good?
Tim

[anonymous_user]

Sorry, 3.0. Was thinking 2.2/2.5 where the case is NOT grounded due to the rubber bushing in the mounting bracket.

[DustyR/T]

I have added additional grounds, and it was arcing from the case itself, not the pos connector on the alt. It was arcing to the strut brace ~3 inches. It's not rubber bushings. I swapped the alt. in DC while on the trip. Just wondering if anyone else was having this problem. Autozone said the alt tested good, but it's not a gauge tester just an idiot light deal. I got the exchange anyways and since then I think it's been ok.