What is this hose?

[BIGBAND39]

Does anyone know what this hose is?  My mechanic is not familiar with older vehicles and thought it was some sort of a PCV system.  I explained to him that road draft tubes were the solution for crankcase ventilation back in the 30's.  As you can see, there is a small leak coming from it.  I thought it may go up to the oil pressure gauge, but I've been told that that hose is only about 6" and isn't an elbow.  I've looked through my master parts list and the shop manuals.  Any ideas?

 

 

[casper50]

BB39 don't take this wrong but any mechanic that could not follow the hose to each end and know what it was for is a mechanic that wouldn't be working on my cars.  lol

[greg g]

Well perhaps a pointer to the part you are questioning would appropriate. I see an exhaust pipe, a copper line, a heater hose and the road draft tube.

PS tell your mechanic to think more Brigg and Stratton and less Toyota. And to quote a post from a few years ago, "If you are going to be driving one of these cars, sooner or later you are going to have to learn to mechanic on it your self!"

Edited July 13, 2016 by greg g

[BIGBAND39]

This is the hose I'm looking for.  Maybe I shouldn't have said anything about the road draft tube to them.  They might have just had the terminology wrong.  As for working on the car myself, I have turned some wrenches on cars I've owned in the past.  Work has just been so crazy lately that I haven't had time.  It's either I have my garage do it for me or the poor old girl sits in the garage all summer.  We can't have that now, can we?    Beside that, I have a garage for storage but not to work it.  Dragging out tools and crawling under a jacked up car and then put everything away afterwards isn't a great time.  I do try to go to the garage when she is being worked on and pick up as much knowledge as possible so I can keep her going on my own soon enough.

 

More to the point, why would I have oil leaking from the road draft tube where it meets the block?

Edited July 13, 2016 by BIGBAND39

[casper50]

Tighten the bolt and see if it quits.  Mine has no gasket it's just the tube shoved into the block.

[Don Coatney]

Don't take me wrong, not doing your own work is fine. I am at that point in my life due to physical limitations. But as has been said paying a mechanic for not tracing a hose to the source is not fine. So my best free advice is for you to trace the line to the source.

[BIGBAND39]

I'll try that.  Hopefully the rubber hasn't shrunk overtime and tightening it will help.  Finally found it in my parts list.

[BIGBAND39]

I hear you, Don.  I had made another post asking if there were any well known mechanics in RI, CT, or MA that could tackle some repairs.  It's just difficult to find someone that still knows about these oldies but goodies.  In hindsight, I think that he had traced it and knew what it was but was using modern terminology for it. 

[Young Ed]

Actually since that road draft tube doesn't come down to the oil pan like it used to his car could have been converted to a PCV.

[desoto1939]

remember this is a draft tube so when going down the road the fore of the air movement from front to back makes a suction at the end of the draft tube and the intake for the air is on the oil filler cap.  This is pulling the fumes and oil from the car. It is like a PCV positive crankcase valve on a modern car. it got rid of the oil smell and that is why these old car always have a specific smell to them.

 

I know I am not explaining this well but maybe Don can provide a better answer.

 

Rich Hartung

[TodFitch]

I've heard that enough sludge can accumulate at the back of the valve lifter gallery to form a dam which will retain some oil. I've not seen this on my engine, but if true then I guess the oil pooled there could leak out around the draft tube, especially if there is no gasket. With a gasket, then I wouldn't be too surprised to have it leak out the draft tube.

 

Where does that hose go? For the Venturi effect to work and actually get some crankcase ventilation the end needs to be in the air flow under the car. If the hose just stops at the level of the frame then it is unlikely to being doing anything worthwhile.

[BIGBAND39]

I will be doing the valve covers soon.  Would I be able to see any sludge buildup?  The motor was completely rebuilt in 2008 and has not seen more than 10K since then.  It would seem unlikely that sludge would occur that quickly, right?  I'll see how long it extends when she's up on the lift again.  I'm not sure if the diagram I posted is to scale, but it looks as if it should extend down to the end of the pan.

[greg g]

Road draft tube = crankcase ventilation exit. Its jod is to vent oil vapor when the car is under motion. If your motion is slow it does not work as well as when the car is going faster. So if the majority of your driving is to putt around town, any vapor left at the junction of the tube and block will condensate back to a liquid and leak. There should be some metal wool stuff in that end of the tube like in the breather filler cap. This will also collect liquid and release it. And if your car never does sustained exercise at full oil operating temp the more vapor/ will need to be vented. The tube should be mounted so that it is vertically plumb, it should have baloney sliced exit with the long end at the front. This creates a?n area of low air pressure at the bottom of the tube which pulls the vapor out.

I have seen some of these tubes bodged into the exhaust pipe under the theory that exhaust flow exit creates a better and more effective source of suction. People also plumb them to the intake manifold and or air cleaner. Like to find out where your's ended up exiting.

[dpollo]

It looks to me like a PCV conversion which was often found on cars from California and also on Military engines.

 

The other end of the hose will go through a PCV valve  (of some sort) and into the intake manifold.   If this setup is not working well, oil could puddle in this area and then leak out.

 

If it is a serious amount of oil.... like a quart every few miles.... then the drain for the rear cam bearing is sludged up  and the excess oil is making its escape at this point.

[medium_jon]

Hey @BIGBAND39 I see you are still occasionally looking at this site. What did your hose turn out to be?