Hi MB experts,
I've searched around but haven't found too much information on this. This is on my dad's 2003 C230 Kompressor coupe. It has 53k miles on it, had service done since new mostly at the dealer with oil changes done in between by me.
He had a check engine light recently while sitting around idling in traffic, and the car stumbled. On my code reader, it pulled a code for misfire on cylinder 2. It sounds like it's a problem with the coilpacks sometimes, so I bought all new plugs and coilpacks and replaced them today.
When I pulled out plugs 1 and 2 though, they were COVERED in oil. To the point where another drop or 2 came off the electrode as I was pulling them out of the head. Looking down into the head, I can see the tops of the pistons have oil on them too. What I find strange though, is there is oil all the way up the threads too (see pic) which I thought isn't typical, as it would be the electrode area and the threads close to it that are covered in oil.
Plugs 3 and 4 were dry, and looked OK, maybe a bit dark but not horrible. I believe these are the original plugs, I don't think MB has replaced them on service A or B.
Coming from an M103 190e, oil on the plugs are typically from the valve stem seals. Is this the same issue on the M271 engine? The oil all the way up the threads of the plugs is making me wonder if the oil could somehow be coming elsewhere? Possibility of a valve cover gasket?? Maybe it's just wishful thinking...
Finally, a second picture is attached. I noticed this hose was NOT attached. It's a hose between the airbox and the head area. Is this that infamous $12 hose (which has been replaced by the dealer)? I put it back on and added a zip tie on it. Where does it go? I'm thinking PCV valve?
Any help greatly appreciated. And I found info on the cam magnet leakage and ordered the parts to fix that today. There was oil in the connectors...