My 86 240GL wagon (B230 engine, with 245,000 miles) lost its rear cam seal along with a homemade "bar" bolted in to hold it in place. I put in a new seal and cleaned the flame trap. The trap did not appear all that dirty. On idle the engine appears to have a slight vacuum when removing the oil filler and holding my palm over the opening. I drove fro about 2 hours on the Interstate and it appears that a little oil is coming out around the oil filler cap. Could just be that I need a new gasket but I am concerned that perhaps the brether box (i.e. below the flame trap) might need to be cleaned(??). Should I be concerned about this and if so how does one clean it?

If all the hoses to the oil seperator (oil trap, breather box) are clean and tight and the vacuum brass fitting is clean. Those hoses can clog up with gunk. Run a wire brush through them. Then yes, clean out the oil trap. I did mine recently with an 89 with 175K miles and it was way dirt. I could hear the gunk rattle in it. Lots of curd came out. The trap actualy flet lighter after I cleaned mine. I longer have oil creaping up to my flame trap.

You may have to remove the intake manifold (easy), to get access to it. There is a wire harness above the oil trap (mine 89). And you'll need a new o ring and a intake gasket.