Exhaust coming our of draft tube - normal?

[delco1946]

Dumb question, but exhaust can/will come out of my draft tube when parked at idle. Is this normal?

[KULTULZ]

Not a dumb question.

An example of a dumb question was me asking my little thumbscrew to marry me ...

... get 'em BUDWEISER ...

[dmsfrr]

Any excess pressure or vapors from the crankcase, lifter valley or valve cover areas of the engine can blow out of the road draft tube. Cylinder blow-by from tired rings is the usual culprit.

An exhaust port crack into the rocker arm / valve cover area might be possible??? I don't know.
A cracked piston? A compression test could rule that out.
.

[Anteek29]

Is it vapor or exhaust gas? Give it a sniff test.

[delco1946]

Hmmm good question Anteek29, I don’t know, it was that barely there wispy cloudy sort of look so I guess it could also be vapor. I’ll work on a sniff test!

[Dobie Gillis]

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Some vapor/crankcase fumes are normal unless it's fogging mosquitos. Road draft systems are inop parked at idle because there's no road draft. A PCV setup takes care of it since the vapor/fumes are drawn out of the crankcase through the carb and are burned in the combustion process.

[KULTULZ]

When was the last time the CCV (crankcase ventilation system) was serviced?

[delco1946]

Sounds like a trick question Kultulz lol. I have no idea, could easily be 1-2 decades. I don’t even know what that includes off the top of my head but can look it up in the service manual to see if it has anything along those lines.

[Daves55Sedan]

The V8 engine has a crankcase ventilation tube with a filter inside the round canister on top. Take that top cannister off and pull out the filter and soak it in a cleaning solution (gasoline, paint thinner, etc) then put it back together.
With todays well refined oils, it isn't necessary to look after the filter on these as often as the original owners manual suggested, because they won't clog up as easily as they did with the crude motor oils of the 1950's.
If you are noticing substantial smoke pouring of of the oil filler cap on top of the engine, it can be a good indication that the PCV filter needs cleaning.
Ahhh, these wonderful Y-blocks are soooo much fun. Best and most durable engine I ever had.

[KULTULZ]

That filter has to be changed on a regular basis. Also the oil filler cap has to be clean (open design) as that is the fresh air inlet for the system.

If there is excessive crankshaft pressure after servicing, it may be excessive ring blow-by and may possibly be corrected with a later design PCV SYSTEM. If that doesn't calm it down, it most likely needs a ring job.

You would then take a pressure reading on the crankcase itself. There should be a slight vacuum if operating correctly.If pressurized, either a non-operating system or excessive blow-by.

Read the description of the system in your SHOP MANUAL.

[Gene F]

The oil will off-gas a bit from the heat. Kinda like if you put it in a pan and put it in your gas grill till it gets good and hot. It will have a vapor coming from atop it.... You don't notice it going doe the road because of the fresh air pulling it away.

[KULTULZ]

FILTER SOURCE - https://www.dennis-carpenter.com/car...reather-screen

It is actually more of an oil/vapor separator.

The crankcase must be ventilated properly. ROAD DRAFT is not a really good system. It has limitations.

[delco1946]

So far I’m not finding anything on this in the manual. My car is also not parked near me so I can’t quickly run out to it. Is the crankcase breather a different name for the oil cap? Mine looks nothin like the above pics but is simply a rounded cap that pushes onto the oiling tube (technical name ). No fumes have ever come out that end so at least that’s some good news.

[Daves55Sedan]

The crankcase ventilation tube and filter (screen) are located on the lower front driver side of the engine block. You can access the filter screen using a 1/2" hex socket and long extension. No need to get under the car, it can be done from above.
After removing the one bolt and washer, pull the filter cap off, then pull the filter screen out. There is a round gasket at the bottom which should be replaced if the gasket is hard as a rock. If you are getting a new filter, the round gasket comes with it.
I have been re-using my old filter for the past few decades after cleaning and re-installing. I have not been inspecting my old gasket. I just leave it laying in the cannister base. If the gasket is leaking a little, I wouldn't know it since I always have an old sock pulled over the bottom of the tube attached with a nylon cable-tie. That sock somewhat reduces the amount of oil vapor exiting the tube, but I have to replace the sock once every couple years as it becomes oil soaked after a while.

[KULTULZ]

You have an actual FORD SHOP MANUAL?

The ROAD DRAFT SYSTEM for your period car (1956) is located as Dave describes. Now FORD changed the design in 1959 for PASS CAR and used a ROAD DRAFT TUBE located on the rear of the valley cover pan. Here are more photos. If not located as described, it may have a later engine block.

As for the 'sock' ...

That tube is shaped at the bottom as to create a vacuum as the car moves (actually while it idles also) which in turn creates the vacuum/air flow to evacuate the crankcase. If the engine drips out of that tube, the CCV is either not operating correctly or there is excessive blow-by. A sock will interfere with that air flow.

The CCV SYSTEM as designed was not that effective to start with. If not maintained properly, it will not function at all leading to crankcase contamination and engine seal/gasket failure(s).