My '90 300SE has a slight miss at idle. I replaced the plugs 5K ago and they looked good. I remember reading here a while back about looking under the hood in the dark.

I did so tonight and noticed some arcing. The wire from the coil is running between the thermostat housing and a little metal bracket so it touches the housing. I see a constant arc at that point. The wire has a slight cloudy mark where it touches the housing.

I also observed an intermitent, random flash in wires #1,2&3 between where thewire comes out of the valve cover and the spark plug. There are more flashes at #1.

I can't remember what this means. The PO replaced the wires about 30K ago, with what I don't know. The shop that has serviced it uses good quality parts though.

Can I simply re-rout the wire from the coil? Or does that grey cloudy mark mean The wires are shot?

You need to replace your wires. Make sure to get original Bosch equipment.
Had a guy buy some wires at Napa once for $29.95 or so. He came to me with the engine shaking real bad. His car even had a hard time starting. He was better off with his old Bosch wires. Anyway, we ended up returning the NAPA wires and getting the originals.
I couldn't belive a store could even sell something like that.

You get what you pay for. There is a reason why Bosch wires cost over $100 per set.

Vin








[Edited by vinamg on 01-14-2001 at 12:15 AM]

Thanks Vin,

AutoZone is promoting Bosh wires now. Are these the same as OEM?

Not too sure, you can check it out. They should come with a warranty card from Bosch. You can also go by the price. I know they cost around $115 for the 6 cylinders.

Another option is to order it from mercedesshop parts.

Vin

On many MB's the OE wires are Beru, & the replacement Beru's are much better than replacement Bosch! The aftermarket Bosch are not solid core copper, but resistor(woven fifer) wires like American cars use.