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Draft Tube Missing?


ccudahy

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I finally got the car out of the garage Saturday, after snowing on Thursday afternoon and 30 mph winds on Friday. Started in on my laundry list of things on the car that need addressing.

 

While removing the the tappet covers to adjust the tappets, I notice the tube was missing from draft tube or is it?  Does this look right? Is this going to cause an issue? Do I need to find a different draft tube? Am I going to need make a new tube?

 

thumbnail_20210530_104404.jpg.128b2b4c4a468a6dda792f5dcbaf3fb9.jpg

Edited by ccudahy
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I can’t find the post I read the other day about the draft tube needing to be installed in the rear most position to help vent the crankcase but Merle explains it here

 

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As long as it is still open to the crankcase/atmosphere, it won't affect the car's operation per se.  Its purpose is to provide the outlet for ventilating the crankcase of gasses - most importantly, volatile ones - the intake is the vented cap on the oil fill tube.  It is much more efficient of the tube is there.  Diverts the crankcase gasses from venting directly in front of the firewall and getting into the cabin, and the tube's outlet location at the bottom of the car uses the increased draft between the car and road when the car is moving to suck air through the system and get those gasses out.  As JBNeal points out, you can make a positive crankcase ventilation system with relative ease using what you have left of the draft tube.  There's at least a couple threads in the Forum covering it, they'd be older.  If you don't desire to put in PCV, then you should ensure the/a draft tube is installed, more for safety than operation.  

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Sorry I have to disagree (again LOL) 

 

Draft tube or Crankcase Ventilator Outlet Pipe as Chrysler calls it, is crucial.. Also length is a factor. It matches length of oil filler pipe for perfect airflow balance. Air in volume, velocity etc match outlet. When car is driven, vacuum at outlet adds to suction. To compensate to much suction, a small chamber is welded to outlet at engine.

 

They obviously where experimenting with optimal crankcase ventilation to remove damaging unburned fuel vapor and moisture. Pre and pro war engines have different length tubes, with and without chambers.

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chrysler1941 is right....the design of the tube and install is critical for proper ventilation on the crankcase...one can repair this with a tube welded back in place IF he has the correct profile for exhaust/suspension or other components to clear.....the main thing is however the tube length per frame application and angle of the cut on the tube to get proper venturi effect while car is in motion as this is a suction system...not just an open tube for exiting gasses etc but it does pass some gasses at idle...

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1 hour ago, Plymouthy Adams said:

chrysler1941 is right....the design of the tube and install is critical for proper ventilation on the crankcase...one can repair this with a tube welded back in place IF he has the correct profile for exhaust/suspension or other components to clear.....the main thing is however the tube length per frame application and angle of the cut on the tube to get proper venturi effect while car is in motion as this is a suction system...not just an open tube for exiting gasses etc but it does pass some gasses at idle...

Or, take a modern approach and install a working PCV system.   Does a much better job of evacuating the crankcase of fumes without polluting the air.  Smells better at stop lights too.

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This appears to be the same draft tube chamber that you have, chamber only with a mesh filter, no real tube, but a crimped, vented cap on the end of the short tube. I assumed it was factory. The engine was a D42 removed from a pick up.

DSC06970.JPG.JPG

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Yes, there is a mesh screen in the end pointing down.

 

I got nervous not seeing no tube. As most engines pictured just show an elbow with a long tube. This car has been fighting me since I got it last August, and figured just another thing gone wrong that needed fixing. I also seen in another post from @desoto1939 had said that there was an option vent with no tube, like the one @rekbender pictured.

 

Thanks to all who gave advice!

Edited by ccudahy
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