i have an oil leak on the back of the engine around the valve cover gasket area and i have been reading up on the oil leak/flame trap relationship here on brickboard. i thought maybe i had a gasket leak, then i thought maybe a plug leak going on. ive been tinkering on it for the past couple hours (trying to locate, remove and then clean the flame trap, and then trying to locate the leak while the car was idling) and i have some questions. first, the flame trap looked clean (although it looked rough--cracked and not fitting together all that well) but what about the black box below it, what is that, and can it get clogged and cause these problems, too. second, i was attempting the oil filler suction test (putting my hand over the oil fill opening to see if there is any suction) that i heard about here and found something that seemed noteworthy to me (i am not a mechanic!!) with my hand at the back of the engine, i could feel air (and oil) blowing out of what i assume to be the end of the camshaft (the circular spinning thing--like i said, i am a novice mechanic at best)... when i removed the oil filler cap, the air stopped blowing, i replace the cap, and you guessed it, the air is blowing oil all over my firewall. so im wondering if my problem is a gasket, too much pressure due to a clogged flame trap (or somewhere else i should check), a combination of both, or something altogether different.

thanks in advance for any info/advice.

Rear cam plug has jumped ship! It's a common problem with the B230F. Try a search on cam plug.
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85 245 DL - 91 Mazda MX6 Turbo

The black box is the oil trap. With the flame trap removed, stick a hose on it. Blow with the oil filler cap on, and you should have no leak (although you probably will at the rear cam plug you're talking about). Then remove the oil filler cap, and you should be able to blow freely, feeling the air come out at the cap opening.

If that is flowing freely, your problem must be with the flame trap or the vacuum hoses/ports it connects to. Fixing whatever it is may stop your leak, or you may need to replace your rear cam plug.
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David Armstrong - '86 240(350k km?), '93 940T(270k km), '89 240(parts source for others) near Toronto, ON

Something altogether different ...... To me it sounds like the rear cam end plug is missing. If you can reach behind the valve cover and feel the camshaft with your fingers (engine off!) then the plug has fallen out ! cheap fix, go to dealer and request part #1336763 & reinstall

any suggestions/recommendations on how to install cam plug... do i need any sealant?
thanks

I've only replaced one once, but I didn't have to take anything off or apart.

With the old one out, I wiped the hole out and started the new plug in by hand, then levered it home with a piece of wood. I used a wood block held against the firewall as a fulcrum, and another block spanning the plug so it would go in flush.

Don Foster's picture below shows dimensions for a plug retainer strap you can make and install to make sure the plug stays in.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.