This coil was purchased just a couple months ago at Autozone in California while troubleshooting a problem that ended up being the fuel filter. On Father's Day this year I started feeling an occasional misfire that increased in frequency to the point where I could barely drive the bus. Swapping in the old original Bosch coil got things back where they should be.
Here's the shiny relatively new coil:
First I drilled two holes to drain the oil. I set it so when I drilled the vent hole the drain hole would be right over the opening in my drill press platform. Wasn't much oil in there.
The coil after going around the top with a reinforced cutoff wheel on my Dremel:
Well, I was disappointed to see just how this thing was constructed. The windings are embedded in paper and only use less than half the available space. There's an obvious scorch mark in the paper nowhere near the windings. Odd. The windings are two separate sets as expected around a steel sheet metal box.
That scorch mark may or may not be why the coil failed. I haven't unwound the thing, and probably won't. The paper just disintegrates when I tug on it. I would, however, be curious to compare this to a known good quality coil. But I don't have one to cut up, so this will have to do for now.
I would have returned this turkey to Autozone if I could find the friggin receipt. Grr....
(Please ignore the messy garage. The apartements have been undergoing painting for 2 months now and all my patio stuff is in the one car garage.)