To jump a half inch, that is in the area of at least 10,000 volts. I'm very familiar with the 25,000 volts that drives older tv picture tubes, and that will arc up to two inches. The only way you're going to get that kind of voltage there is from static electricity. That would have to come from the serpentine belt. Try running the engine with the belt removed, or use a piece of wire with one end grounded, and touch the other end to the rotating belt to see if the arcing stops.
I suspect your engine has a vibration damper with the pulley for the belt as an outer ring. That ring is bonded to the center part with rubber, so that ring and the belt are insulated from the crankshaft. The static charge would be grounded by the bearings in the generator or power steering pump if it was being generated there, so to be arcing down low, that might be closer to where it's being produced. Holding that grounded wire near the generator or power steering pump might not solve the arcing then. Move the wire closer to the crankshaft pulley and try again, but be careful to not get your fingers in the belt.
You also might try dribbling a little water on the belt to see if that helps dissipate the static.
Sunday, June 7th, 2015 AT 11:42 PM