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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: OldGray on February 10, 2016, 12:02:35 pm

Title: Breather tube...?
Post by: OldGray on February 10, 2016, 12:02:35 pm
I assume that the vent in the valve cover (in this pic) goes to the connection at the Air Cleaner... yes?  Does anyone know the part numbers (or names) for the hose and the proper breather that goes into the Valve Cover?  I just got this truck and have no idea what all the PO did...

(https://lh3.googleusercontent.com/-CdYFAxxnYXc/Vrt6XFWcQhI/AAAAAAAAGog/rjG3VnN9ulE/s576-Ic42/100_2817.JPG)
Title: Re: Breather tube...?
Post by: bd on February 10, 2016, 01:22:07 pm
The engine should have a crankcase vent tube that connects between the plastic vent filter nipple in the air cleaner assembly and the valve cover.  Generally, an "L" shaped steel tube inserts through the valve cover grommet and makes a 90° turn when it is level with the vent filter nipple; it couples to the vent filter with a short rubber hose.  The PCV valve (imaged in the valve cover grommet), should be in the opposite valve cover and connected to a 3/8" manifold vacuum nipple protruding from the baseplate of the carburetor.  Use PCV rated 3/8" vacuum hose to connect the PCV valve to vacuum, so that it doesn't collapse. 

The PCV (Positive Crankcase Ventilation) system removes combustion and water vapors from the crankcase to prolong engine service life and help prevent the formation of sludge.
Title: Re: Breather tube...?
Post by: OldGray on February 10, 2016, 02:21:46 pm
Do you happen to have a pic of the Crankcase vent to the Air cleaner? 

There is a PCV on the other side connected to the nipple under the carb as you said.  So I just need to see what the part looks like between the passenger side valve cover and air cleaner. 

Been a loooong time since I worked on old motors (and I wasn't really good when I did...)!  Thank you!
Title: Re: Breather tube...?
Post by: bd on February 10, 2016, 03:27:10 pm
Should be similar to this.
Title: Re: Breather tube...?
Post by: OldGray on February 10, 2016, 04:02:48 pm
OK - thank you.  That is what I thought.  Can't seem to find on the Autozone website - might be a junkyard part.
Title: Re: Breather tube...?
Post by: rich weyand on February 10, 2016, 06:09:41 pm
I just used a fake breather cap and a rubber hose.  I put a 90 in the rubber hose to get the angle to work.

(http://users.rcn.com/weyand/smalls/imag0743small.jpg)
Title: Re: Breather tube...?
Post by: OldGray on February 10, 2016, 07:23:09 pm
Already found and installed one! 

As luck would have it, I have a friend in the neighborhood who owns a '79 (like mine) AND has a couple more derelict Chevys on his property.  All I had to do was pirate one and knock the mud-dobber nest off of it.