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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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That is the air supply to the valve cover for the PCV (positive crankcase ventilation) system. Air from the air cleaner housing is supposed to flow through the hose, to one of the valve covers. Engine vacuum, applied to the PCV valve in the other valve cover, pulls the air through the crankcase, sweeping up harmful vapor (mostly piston ring blowby), and dumping the vapor into the vacuum connection on the throttle body (or intake manifold).

When your PCV valve is plugged, or you have excessive piston ring blowby, pressure will build in the crankcase, and will vent backwards through that hose into the air cleaner. Since this excess vapor from the crankcase is flowing through the valve cover, it will pick up tiny oil droplets, and dump oil into the air cleaner housing.

Check for a plugged PCV valve. But, given the results of your earlier compression test, it wouldn't surprise me if you have major piston ring blowby.
 

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Discussion Starter · #3 ·
Ok I have changed the pvc valve 2 times so I am sure its not that. But it more then likely is from the number 3 cylinder blow biased off what you just said here and concluding from that information you have provided.
 
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