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Discussion Starter · #1 ·
I have a 2003 4Motion wagon, 2.8L 30V, automatic. The PCV started leaking a couple days ago, giant vacuum leak out the vent looking port on the side of the hockey puck PCV valve. I taped over the vent to stop the vac leak and that sort of helps but it still leaks and idles rough. If I pop the cap and diaphragm off the PCV valve and just plug the line to intake, it runs great but smokes like crazy out the exhaust! What on earth could make it burn so much oil by capping off the vacuum line to intake???

Tthe part i have on the way is #6 on this diagram:
Auto part Diagram Automotive engine part Automotive exterior Transmission part

It doesn't make sense at all cause people cap off the line to intake all the time and run crankcase to a catch can.
 

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My guess is that when the crankcase pressure control is disabled like that, the much lower pressure within the engine, especially at idle or deceleration, will cause an oil mist to be pulled into the intake manifold. Not so good for oil consumption or the catalytic converters. On the other hand, the catch can approach you mentioned is pretty much how they did it 100 years ago, but usually without the can. The moisture in the crankcase won't 'boil off' so sludge results.
 

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As the engine cycles through its normal rotation and when the RPM's go up and down, there are pressure differences in the crankcase. That PCV valve helps control those fluctuations. With that being disabled you get full manifold vacuum and it sucks all that oil mist / vapor right into the combustion side of the engine which is why it smokes so badly.
 

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Discussion Starter · #4 ·
Your both missing the big point! I had the crankcase completely isolated from the intake. Crankcase was venting to atmosphere, and the intake manifold port capped off! That is how I was expecting to bypass until the new PCV showed up but it smokes to bad.

If I connect the intake port direct to the crankcase, then the smoking quits. That's how I'm driving right now.
 

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Almost like an old school V8, when they used to run a 1/2" hose the back side of the carburetor mounting plate / adapter right up to one of the valve covers. The inside of the intake manifold would almost be plugged up with oily tar like gunk.
Old Ford FE motors had this problem.
And for you youngsters out there, one bank of cylinders would usually have more cubes than your whole engine.
 

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I honestly can't answer that question right now.
But there are 3 hoses that connect to the "crankcase". The two hoses that connect to the valve covers (one on each side) and the third is underneath the intake manifold at the backside of the engine.
So depending on what hoses are or are not connected can change the way the car runs.
And I'll be honest, I can't remember the exact connections, but I think there are two connections to the intake or at least what would be considered intake manifold. There at least three revisions of this the PCV system on our cars.
 

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I know this doesn't give any of the answers you are looking for, but if the car runs ok and it's not smoking, a few days shouldn't hurt anything until the replacement arrives.
 
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