I wanted to tune up my W124 last week, it's been running rough at idle and actually stalls every once in a while (usually when U-turning or making sharp lefts for some strange reason). I took out the first spark plug and noticed coolant had gotten to it, same with the others. I checked my oil dipstick and it does not look milky or strange to me but I snapped a pic and am including it here in case anyone would like to see it. So I'm guessing the valve cover needs to be replaced and should be replaced before throwing the new Bosch plugs in but wanted to get a second opinion. Could it be the head gasket as well? If so, I don't think I'm gonna bother.


Pics are here:
http://profile.imageshack.us/user/xdjordanx

I added one of the front side of the engine to show what the valve cover area looks like for possible leak diagnosis.

Valve cover is definitely leaking, but nothing you are showing should cause the car to stall unless there is so much oil on the spark plug its insulating it from the spark plug wire lead. Oil looks fine, looks like the rings that seal the head from the spark plug holes is leaking. Those usually come with the valve cover gasket kits. Stalling could be related to several things. Check the harness first, if its crumbling start with that. All of those white spots on your wires means you are loosing spark to the valve cover because your insulation is breaking down. You can replace or wrap in electrical tape to get you by.

Thanks Quicksilver500, I'm going to replace the spark plug wires as well and I'll check the wiring harness, I know it was already replaced once by the previous owner.