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Radiator Cap

Discussion in 'Early CJ5 and CJ6 Tech' started by Paulietools, Nov 8, 2022.

  1. Nov 8, 2022
    Paulietools

    Paulietools New Member

    Lampasas, Texas
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    So the manual shows both a 7 lb and 15 lb rated cap for the F head.
    How do I know which is which and when the transition occurred?
    I have a 67 but the radiator is held in a frame. The radiator is not directly bolted to the core support. It doesnt match any photos I have seen so far.
     
  2. Nov 9, 2022
    Rick Whitson

    Rick Whitson Detroit Area 2024 Sponsor 2022 Sponsor

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    IT should say on the radiator cap what presser it is, I have a 13 lb. cap on my F 134. Your radiator should be mounter in the grill with four bolts. What you are seeing is maybe is the should behind the radiator. Good Luck.
     
  3. Nov 9, 2022
    PeteL

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

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    The higher pressure will allow a higher operating temperature, depending upon the the rating of the thermostat used.
     
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  4. Nov 9, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    I've got a 7lb cap on mine.
     
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  5. Nov 9, 2022
    Paulietools

    Paulietools New Member

    Lampasas, Texas
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    Therre was no radiator cap when I dragged it home. Its something I need to address.
    Definitely no fan shroud.
    jeep rad.jpg jeep rad 2.jpg
     
  6. Nov 9, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    That looks like it's original.
     
  7. Nov 9, 2022
    Lockman

    Lockman OK.....Now I Get It . 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Standard 12-13# is all that you need. Don't overthink this stuff ( Like I Do ! ) :schooled:
     
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  8. Nov 9, 2022
    Paulietools

    Paulietools New Member

    Lampasas, Texas
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    I am pretty sure the brackets at the top of the radiator are not OEM. They look homemade. The white foam shoved under them is suspect.
     
  9. Nov 9, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    What temperature thermostat is in it?
     
  10. Nov 9, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    You're correct on that part. I just realized the radiator isn't soldered to the original side brackets.
     
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  11. Nov 9, 2022
    PeteL

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

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    yes. Those solder joints at the tank are a tender spot. Fairly easy fix, however.
     
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  12. Nov 9, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    My suggestion is to have the radiator checked and cleaned if necessary by a competent radiator shop.
     
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  13. Nov 9, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    And to flush the engine out too, there is no telling what is in the engine as far as some kind of residue.
     
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  14. Nov 9, 2022
    Paulietools

    Paulietools New Member

    Lampasas, Texas
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    So at this point I have flushed everything with a garden hose and filled the system while I play with carb and trying to get it to start and run ( whole different topic ).
    Until I get a cap I dont know if the system leaks under pressure. It doesnt leak under gravity or nonpressured running.
    The heater core leaks but just disconnecting that for now.
     
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  15. Nov 9, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    Flushing the engine out with a hose should be sufficient if you didn't have any loose particles coming out. You would do yourself a big favor by having a shop check the radiator core and clean it and solder the core to the supports. Those homemade braces shouldn't be needed. They could also pressure test it to see if it will hold with a 13# cap.
     
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  16. Nov 9, 2022
    Paulietools

    Paulietools New Member

    Lampasas, Texas
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    So the brackets across the top are definitely something that is homemade. The frame that the radiator is held in by is not a homemade affair. The frame seems to match the radiator fairly well.Ii have no idea what its off of or if it is even from the Jeep world. It is odd that the mounting holes for the frame appear to match the core support correctly.
    I think I am going to spend the $9 on a new cap and pressure test it myself.........
    If it fails my test then I will have to send it off to get repaired. Hopefully I get lucky.

    I replaced the tstat when I replaced the hoses and the tstat neck and its rated for 180 degrees.
     
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  17. Nov 9, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    The frame part is original Jeep. It's not odd since it is supposed to match.
     
  18. Nov 9, 2022
    PeteL

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

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    Originals are well worth repairing. Much heavier copper than modern replacements, and can easily last another 50 years.
     
  19. Nov 9, 2022
    Paulietools

    Paulietools New Member

    Lampasas, Texas
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    I find it really interesting that the frame and radiator are original Jeep parts.
    I haven't seen anything like it in all the pictures I have looked at.
    Hopefully can get it running and pressurized this weekend.
     
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  20. Nov 10, 2022
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
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    I looked in the service manual and the cap for the F head is specified as "7 and 15 psi". However there is no amplifying information about when you would use one over the other. I have a 180 degree thermostat in mine and a 7 psi cap.
     
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