Oil filler cap

While surfing here the other day I saw an oil filler cap with a hose on it. I guess that hose goes back to the valve covers or the pcv system to relieve pressure in the main oil gallery that comes from blow by. I'm having an issue with oil being forced up the oil fill tube leaking down and that being blown all over the engine compartment especially on the air filter. I do not have the original air cleaner and the unit on mine is just an open element style. My question is two fold did that hose connect to the aircleaner like some did back in the 60's and second does anyone have a source for that style cap.
Thanks

oops I have a 72 304

 

IIRC (!) the hose goes from the air cleaner, to the filler and is the inlet for air to the crankcase. The PCV system uses engine vacuum to pull vapors (and air) from the crankcase in at the base of the carburetor, to be burned with the fuel. There should be a filter of some type on the inlet (typically on the inside of the air cleaner housing), so that only clean air gets into the crankcase.

If connected properly, there should be a draft pulling the oil vapors back into the crankcase. One possibility is that your PCV system is not working, and the oil vapors are coming out through the filler cap, rather than air going in. With the stock system in place, the oil vapors would typically go up into the air cleaner housing and either wet the filter or puddle in the bottom. This is a common problem on engines with a lot of blow-by, but not typical.

 

You can see the piece of 1/2" hose coming off the air cleaner housing in the diagram that goes to the cap. The factory oil cap has a bretaher filter built into it. the Jeep p/n for the cap is/was: J3220248.

 

Thanks Guys. I did replace the PCV valve a couple of weeks ago but that didn't seem to help. I did make a mod though that although does not stop the oil from dripping out of the filler cap it does keep the fan from blowing it all over the engine compartment. I took a piece of 3" pvc pipe cut it to a length that is just long enough to stick above the filler cap when placed over the tube,cap unit. The oil still drips but down the tube and onto the intake. Not the best but doesn't distroy the paper filter element.