1954 331 Engine Vacuum Tube Question

[55 ledsled]

Hello,
I just fired up my 54-331 for the first time and noticed that the large air tube that goes from the valley pan down and out, seems to letting a little light blue exhaust looking air out of it. Is this typical? I just thought that this was an intake for vacuum or vise-versa. I do have the vacuum line plugged and not connected to the wipers or anything else if that makes a difference? The engine seems to purr like a kitten though. Just thought I would ask the Caddy Gods to make sure.
Thanks

[G Pennington]

That is your crankcase breather.  A little blow by is normal.  In the 60's, they started routing the breather back into the intake (PVC valve).

[Jay Friedman]

The way it works is that the bottom of the tube is cut at an angle.  As the car moves, the angle creates a slight vacuum that draws air through the crankcase and the oil filler cap (whose metal shavings inside act as a filter) and out the bottom of the tube as G Pennington said. 

Keep the oil filler cap's interior clean by occasionally washing it out with mineral spirits or kerosene. 

[Jeff Rosansky CLC #28373]

Dont worry about it at this point--When we woke ours up after years of sleeping I could just watch the smoke come out of it. Now that she has run a bit which I think has unstuck the rings, I don't see much coming out of it at all. If you follow the tube up it goes under the intake and attaches to the valley cover.
Jeff

[55 ledsled]

Awesome! Thanks a lot for the info. Very helpful.

[wrench]

Technical term:

Road draft tube...

https://en.wikipedia.org/wiki/Crankcase_ventilation_system#Road_draft_tube