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WTF PCV Oil leak?

Joined
Aug 11, 2015
Location
Central NH
Trying to figure out a really weird intermittent oil leak on my '79 w/b21F.

Noticed the leak after an oil change a few weeks ago. Had just replaced intake manifold and cleaned oil breather box by blasting it with carb cleaner, shaking, repeating, etc. Thought I'd cleaned it well. Replaced flame trap with a brand new FCP one.

Here's the thing - it seems to be a slow drip while driving/at high revs, but as soon as I stop and idle after driving, it GUSHES oil from the area of the bellhousing/maintenance plate for 5-10 seconds. After that it slows to a slow drip again. Leaves a mess on the ground, a puddle 6 inches across. Drive again, stop and idle, and the oil gushes again for a few seconds. Oddly it seems tied to the amount of driving I've done in between stops - 50 miles of driving is a giant puddle, 10 miles is a smaller puddle.

I know it isn't losing oil this rapidly while driving - I put 200 miles on the car today and the oil is still at least 3/4 up the dipstick. Pulled the inspection plate and the flywheel is dry - so that would rule out RMS. Picked up a UV kit and aside from some slight seepage from the oil pan gasket, I can't really find the source. Guessing this is some PCV weirdness but otherwise I'm stumped. And yeah, I've checked cam seal, crank, head, all the usual places oil would leak. Help!
 
There isn't a breather box on a 79. You have the valve cover vent. The channel inside the valve cover can varnish up and clog which could cause excess pcv pressure. The leak that can happen at the back of the head is the half moon seal for the valve cover can push out and leak oil from the engine. Try checking those out.

If the engine has been replaced with a 1981 or newer B21F. Then there could be a breather box on the side of the block under the intake manifold. But original strock is the valve cover vent only on a 79.
 
Sorry, the engine is an 81. I kept the vented valve cover so I have the best of both worlds supposedly. Definitely cleaned the entire breather box to what I thought was a good point.
 
Still got the half moon seal to check on the back of the valve cover. Also you may still have a clogged oil drainback hose in the breather box.
 
Brand new oil separator and o ring seemed to fix this. Still need to do some highway driving to be sure but it's leaking an occasional drop instead of a torrent...
 
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