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71 Radiator Drain Valve

Discussion in 'Early CJ5 and CJ6 Tech' started by Wmi68CJ5, Apr 1, 2022.

  1. Apr 1, 2022

    Wmi68CJ5 Let the Sun Shine! 2020 Sponsor

    Twin Lake MI
    Aug 10, 2006
    So I am trying to drain my cooling system for the first time since I've had my jeep in running order and for the life of me I don't remember what is open or what is closed? I crank it all the way both ways and drips are all i get.


  2. Apr 1, 2022

    Bondo New Member

    Greenfield Me.
    Dec 17, 2021
    Ayuh,.... Turn it lefty loosy, 'n blow back into it a tiny bit with compressed air,......

    Probably a crud build up right there at the bottom,.... ship settles,....

    Or, if yer drain valve allows, run a nail or screw into it to dislodge any crud,....
  3. Apr 1, 2022

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Medford Mass USA
    Aug 10, 2003
    The drain valve is a "petcock."

    petcock (536 x 392).jpg

    The larger thread is an ordinary pipe thread that threads into the bottom of your radiator. The handle is connected to a center that pushes the tapered plug out of the end. The coolant comes out through holes in the threaded center and out the middle of the handle.

    This looks like the center is left-handed threads. So your "lefty loosey" turning threads the handle inwards but opens the valve. That plug end moves away from the pipe threads and opens the valve.

    The moral here - whichever direction threads the handle end into the fitting and toward the radiator is the "open" direction.

    JMO - remove the bottom radiator hose to drain.
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