Should my M60 igniton coils arc sometimes???

[bimerguycw]

I noticed a few of the 8 coils arcing a little while running the engine the dark and the idle did not stumble when I saw the arcing. The arc ran along 1 of the sides of the square shape. Also, the arcing was infrequent, about every 30 seconds or so. The coils measure okay with the ohm-meter and my plugs are burning normal.

Is this typical for infrequent slight arcs and are the coils going bad?

Thanks

[winfred]

bad boots maybe

[tim]

oil in plug holes?

[632 Regal]

first thing replace the plug boots! if the bottoms are oily remove the offending cylinders plugs to drain the oil, wipe the residual. get new plug boots and a valve cover gasket. if you let this go you can fry the coils and DME, which you dont want to do.

[bimerguycw]

Replaced them and when replacing the plugs.

[bimerguycw]

I changed the Bosch Plat 4 with NGK's and inspected the plug area and boots and no oil and boots new and no arcing marks(white powdery marks)

[ryan roopnarine]

the arcing was probably the result of cracks in the coilpacks themselves, if the coilpacks are anything but new. i took off my original bosch coils, which, with the naked eye, look solid. but when i used a magnifying glass, i saw that almost all of them have hairline cracks, some of the cracks are not all the way through, but most were. those cracks allow the oil to leak out, and when the oil can leak out, the "charge" will jump out of the transformer and ground itself on your valve cover. if lowell says that bad coils can fry an ecu, i have no doubt that a cracked coil condition can do the same. check them with a magnifying glass if you are just changing boots, or cleaning them up and leaving the same units on.

[bimerguycw]

I will replace them as I do not know the age condition of them even though they measure within spec for resistance but visible arcing cannot be good based on what I'm hearing here.

Thanks.

[632 Regal]

what NGK's did you use?

[tim]

I'd only use the Bosch F7L DCR's. I've never heard a good story about moving away from these plugs in a BMW that required them (which seems to be all the VANOS systems in the '90's.) If the ngk is a multi ground resistor with the exact heat specs, I guess its ok. But you have to gap the ngk's no?
.90mm-1mm is the spec and the bosch's come .90mm out of the box and are non adjustable.