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L-Head Temperature Questions

Discussion in 'Early CJ5 and CJ6 Tech' started by Blue CJ6, Jun 1, 2014.

  1. Jun 1, 2014
    Blue CJ6

    Blue CJ6 Member

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    I have a 1946 L-Head in my 1966 CJ6 that was installed by the previous owner. It runs well and was supposedly rebuilt about 13,000 miles ago. All winter I noticed that the temperature level was about 3/4 to 7/8 up on the gauge. So this spring I pulled out the thermostat, wondering if it was the hotter 180 degree thermostat that was in there, and wondering if it would run cooler without one. If it still ran hot, then perhaps it would be the temperature sending unit, or waterpump.
    We'll, it did run cooler, at about half on the temp gauge. The thermostat was the 180 degree one too. So my question is would it hurt the engine to run it for the summer without a thermostat since I just put it all back together? A guy at Autozone said it would warp the head and a bunch of others bad things if I ran it without a thermostat. Also, if I need to put a thermostat back in, and if I put the cooler 160 degree thermostat in, will it run at halfway on the temp gauge, where it seems it should run?
    As always, thanks for the input and advice.
    Dave
     
  2. Jun 1, 2014
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    You should run a thermostat, it not only controls the temperature but it helps keep the temperature equal through the whole block. Put a mechanical temperature gauge in there instead of the electric one. Electric ones can be hit or miss on accuracy. I do wonder if it has a 6 volt sending unit and a 12 volt gauge.
     
  3. Jun 1, 2014
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    Bad for the oil to run w/o a thermostat - water condensation in the sump never gets burned off. I would use a 160º or 165ºF unit, based on F-head experience, but check the FSM.

    Check your gauge too - are you sure it's true?
     
  4. Jun 1, 2014
    Twin2

    Twin2 not him 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Virginia Beach, VA
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    I agree . you should run thermostat , it controls the cooling cycle in coolant passing through radiator . are you sure radiator has flow . and yes could be faulty gauge . do you have a hand held temperature gun , they really help . when a gauge is in question . no need to remove cap to test temperature
     
  5. Jun 3, 2014
    Blue CJ6

    Blue CJ6 Member

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    Thanks for the replies. Any idea what a cross reference might be for a 160 degree thermostat for an L-Head? When you mention anything at any parts store that they can't punch in their computers, they kinda give you the deer in the headlights look. I think their computers only go back to 1969 or so for Jeep.
     
  6. Jun 3, 2014
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    Computers? Find the parts store with the old guys up front and paper parts books still kept in the back.

    The place where they will have the part number in their head.
     
  7. Jun 3, 2014
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    Not an expert on L-head, but I think you can run a F-head thermostat using an adaptor sleeve. Maybe you already have that?
     
  8. Jun 3, 2014
    Blue CJ6

    Blue CJ6 Member

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    No adapter sleeve that I saw. Just a really rusty piece of metal that I found out was a thermostat housing retainer. There is an old Napa store here in town that uses old books. I remember now buying an oil filter from them for a 1942 Ford N tractor I had. I was really surprised that they had it. Thanks for jogging my memory!
     
  9. Jun 4, 2014
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Walck's is one of the many vendors that will have what you need including the retainer, which could be considered an adapter.
     
  10. Jun 4, 2014
    EricM

    EricM Active Member

    Southern California
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