I have an 89 240 with, I think a B230F engine with 171K miles. It blew the seal out that is at the back of the head just below the head gasket. It looks like it was for a distributor to be driven off the camshaft. I replaced the seal, and now it's leaking oil from the filler cap.

I'm wondering if there is a problem with too much pressure inside my valve cover causing oil to be forced out. Is there a vent of some sort I should check, like a PCV valve?

BTW, is there any trick to washing the engine? Since it was covered with oil, I gave it a good washing. I've washed many car engines over the years with little problem, but this car started, ran for a few blocks, then stalled at a stop light, stranding me. It took 2 days of letting it dry out before it would start again. Is Sweden a dry country?