Recently failed smog.....3 times! High emissions. I think I finally figured out the problem. After replacing the EGR valve, sea foaming, and having a new cat installed (I had the original on and it was due) I still failed smog for high HC, although it went from like 1499 to about 400 with the new cat, still kind of high. So I decided to check my spark plugs and low and behold they were wet with what appears to be oil. So I decided to order new valve stems because I noticed that I have also been burning oil relatively fast. Here are my questions:

1.) Can oil leaking into the cylinder head cause high HC?

2.) Is there a way to clean the cylinder head without disassembling everything? Will sea foaming it/ fuel cleaner be enough?

3.) I am replacing my old plugs (Bosch Super H9DCO) with Champion Super (RS12YC), obviously the Champions are resistor plugs that I have and I have a set of brand New Bosch wires, will this work? I've never used any other plugs other than the non-resistor Bosch, they stopped making them so they are hard to come across, but I know I can get them from the dealership I was just curious if there would be any problem using the Champion non-resistor plugs (copper core).

4.) Changing out the valve stems seems like a pretty straightforward job, I've never done it before so are there any precautions or known calamities that a first tier is likely to make? I.e, dropping something inside the crankcase, breaking some nipple or screw, etc?


Thanks in advance guys.

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1990 190E 3.0L