Road Draft Tube Leaks


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By jabonero - 14 Years Ago
I have had trouble getting the road draft tube to stop leaking. I have a block off plate to eliminate the road draft tube but what will I need to do to when this is eliminated ?
By MoonShadow - 14 Years Ago
Did you clean the drain back tube thats on the inside of the breather? Carry's excess oil back to the pan. Chuck in NH
By oldcarmark - 14 Years Ago
Check the drain tube in the cannister and the filter.If you remove it and plug the opening you MUST install a PCV system.If you remove and plug it without some way of ventilating the motor you will have pressure on the seals and oil leaks.
By Y block Billy - 14 Years Ago
Below the drain back tube there is a low spot where moisture can collect. all the breathers that I found leaking was because moisture had corroded the base below this point. and when I thought the tube was leaking it was actually coming down the back side of the tube and dripping off the tip.

I wonder how many people have gotten rid of their y's for a stupid drip as such?

By Ted - 14 Years Ago
jabonero (3/20/2010)
....I have a block off plate to eliminate the road draft tube but what will I need to do to when this is eliminated ?
For short term applications the road draft tube opening on the block can be covered or blocked off without any further modifications. If driving for any distances though this will push an excess of blowby under the hood and very likely create a burnt oil odor that can be smelled within the vehicle. The long term fix adds the installation of a PCV valve system which will minimize any excess of blowby coming out at the valley vent and helps to reburn this through the engine. PCV valves can be installed either in the valley pan or the valve cover but in either case must feed back into a direct vacuum source either at the intake manifold or at a vacuum port directly below the carburetor. Using a PCV valve for a similarly sized engine such as a 302 Ford gives several different options on mounting or installation.

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Here are some past posts on the subject. Doing a search will bring up a multitude of others.

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Blocking off the road draft tube
Crankcase evacuation
Finned valley pan and PCV valve installation 
Installation of PCV valve into the top of the block
Installation of PCV valve at top and rear of block 2 
Modifying valve covers for PCV valve installation
Valley pan PCV valve installation
Valve cover baffle for PCV valve 
Why a PCV valve or system?
Why the PCV must be at the top
By MoonShadow - 14 Years Ago
Ted,

Could you install a PCV in the cover where the old draft tube was? I think some of the block off's from the VW's will fit and has a threaded hole in the center. Might have to put in a elbow or something so it couldn't suck oil from the pan (if it splashed that high). Seems like the lower the better? Chuck in NH

By Ted - 14 Years Ago
MoonShadow (3/22/2010)
Could you install a PCV in the cover where the old draft tube was? .....Seems like the lower the better?
The simple answer is No.  There is just too much oil being misted around in the lower end of the crankcase to keep oil out of a PCV valve that has its inlet side located down low.  Simple physics will dictate having the PCV valve inlet at the top side of the engine due to heated air rising to the top and any residual moisture that’s in the air also being carried to the top with that same heated air.  It’s also desirable to keep the line as short as possible between the PCV valve to the intake or carb connection.
By San Diego Ron - 14 Years Ago
Just solved my Draft Tube problem...after cleaning replacing filter and still leaking had car lifted looking for solution to another problem when noticed I could move the tube by hand away from the block causing the oil to run down side of block instead of down OUTSIDE of tube. Something for you to check