3/8s NPT thermostat connection points - fan relay & water temp gauge

Heating / Cooling / AC

  1. cudajames

    cudajames FABO Gold Member FABO Gold Member

    Messages:
    952
    Likes Received:
    285
    Joined:
    Apr 10, 2014
    Location:
    San Jose, CA
    Local Time:
    2:43 PM
    At this point of my motor installation, I am working on water temperature gauge (part of a external gauge cluster) and electric fan relay

    1991 LA360 Stroked to 408
    Eddy 7576 RPM Air Gap - existing 3/8s using for heater hose
    Eddy Heads - 60775s

    The electric fan relay - thermoswitch is 3/8 npt ( I can use 1/8 npt) - if I want to connect to the intake manifold
    Water Temp gauge - capillary is also 3/8 npt with a fixed fitting

    I am sure this is common - where and how is everybody connecting these switches/relays?

    I did find a water neck spacer that has two 3/8s ports. Anyone using one of these?

    thanks for the help/education

    bolts and fittings - eddy 7576.jpg

    mez-wn0028s_w.jpg
     
  2. sireland67

    sireland67 Well-Known Member

    Messages:
    7,942
    Likes Received:
    1990
    Joined:
    Oct 27, 2010
    Location:
    WV
    Local Time:
    5:43 PM
    That water neck will work fine.
     
  3. cudajames

    cudajames FABO Gold Member FABO Gold Member

    Messages:
    952
    Likes Received:
    285
    Joined:
    Apr 10, 2014
    Location:
    San Jose, CA
    Local Time:
    2:43 PM
    How is everyone else connecting fan relays and water temp gauges on their cars?
     
  4. sireland67

    sireland67 Well-Known Member

    Messages:
    7,942
    Likes Received:
    1990
    Joined:
    Oct 27, 2010
    Location:
    WV
    Local Time:
    5:43 PM
    Well I have just drilled and tapped the intake on my LD340 on my duster, I found that thermostat spacer after I already drilled and tapped the intake.
    I used the spacer on a LD4B on my old truck and it worked fine.
    I also drilled and opened up a port on a mag M1 duel plane I had.
    The spacer is easier.
     
    • Thanks! Thanks! x 1
    • TrailBeast

      TrailBeast Slightly Twisted Member

      Messages:
      19,615
      Likes Received:
      6089
      Joined:
      Mar 11, 2011
      Location:
      Arizona
      Local Time:
      2:43 PM
      I run an aftermarket temp gauge and sender for a gauge in the factory spot in the cluster, but those thermostat spacers are great for adding a place for the sender.
      One thing is you want to use as little extra fittings as possible.
      Even one adapter on your fitting will throw your temp reading off quite a bit.
      One thing I would be sure of is that the threaded holes in that neck adapter has the correct seat for the aftermarket sender or you will have to run the adapter fitting and it may not let the sensor part of your sender get all the way into coolant.

      For fan relays I connect direct to battery positive and a fan ground wire as short as possible.
      Then your fan switch can switch the relay.
      I like to use a separate relay even though the fan controller I run is capable of handling the load, I would rather blow a 10 dollar relay than a 60 dollar fan controller.
      This way the 60 dollar fan controller is only used as a switch and takes a lot less abuse.
       
      • Thanks! Thanks! x 1
      • mopowers

        mopowers Well-Known Member

        Messages:
        3,926
        Likes Received:
        1100
        Joined:
        Feb 15, 2006
        Location:
        West Sacramento, CA
        Local Time:
        2:43 PM
        I ran my water temp gauge to the 3/8 npt fitting on the drivers side of the thermostat and I opened up the 1/4 npt hole to 3/8 npt for the heater hose.

        They make plenty of adapters to use the existing holes also.
         
      • cudajames

        cudajames FABO Gold Member FABO Gold Member

        Messages:
        952
        Likes Received:
        285
        Joined:
        Apr 10, 2014
        Location:
        San Jose, CA
        Local Time:
        2:43 PM
        The thermostat spacer states 3/8-npt which is the same size of the two senders I need to use. And the spacer is about the same cost as buying 1/8-npt fan relay

        I am starting to mock up the fan wiring and keep what Trailbeast says in mind. I am getting close
         
      • sireland67

        sireland67 Well-Known Member

        Messages:
        7,942
        Likes Received:
        1990
        Joined:
        Oct 27, 2010
        Location:
        WV
        Local Time:
        5:43 PM
        One thing on the spacer I found out, just use a regular gasket on each side and ditch the o-rings, I could not get the o-rings to seal.
         
      1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
        By continuing to use this site, you are consenting to our use of cookies.