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Coolant Expansion Tank?

Discussion in 'Early CJ5 and CJ6 Tech' started by dougs1963, Jul 3, 2009.

  1. dougs1963

    dougs1963 New Member

    Has anyone added a coolant expansion tank to thier radiator system?

    If so any recommendations? Free-air vs pressurized?

    I replaced the PO installed aluminum rad, that required 3 repairs over a 12 month period, with a custom copper rad. I kept the electric cooling fan. The fan seems to kick on at the right temp but once on never shuts off until the car has been off and has cooled way down.

    Generally the system seems to run a bit warmer than before, and the radiator tends to drop some fluid through the expansion overflow a few minutes after stopping. I'd rather not leave rad. fluid on the street/parking garage etc. wherever I go.

    Thanx,

    Douglas..
     
  2. bkd

    bkd Moderator Supreme Staff Member 2022 Sponsor

    I bought and installed a universal "open air" unit from Napa....$10-$12.......works great
    Jim S.
     
  3. Project71-5

    Project71-5 BACON

    Yep, I added a universal overflow tank from Autozone. IIRC it was around $20.
     
  4. OzFin

    OzFin Vintage Jeep Guy

    Free air is the one, pressurized tanks are to fussy. The NAPA / Autozone one or simular is good.
     
  5. lamar

    lamar Member

    Be sure the one you get has a bracket that the over flow will sit in. The ones that use a single sheet metal screw that physically attach the the plastic bottle to the jeep will not hold up on rough trails.
     
  6. windyhill

    windyhill Sponsor

    I used the same universal one. With one screw then went to Home Depot and got a T bracket from the Simson bracing section in framing. bent the tabs around the side and bottom of the tank and mounted it to the back of my light bracket on the 3B worked great for 8 + years now.
     
  7. dougs1963

    dougs1963 New Member

    Thank you all.

    Seems that ' free air ' is the way to go.

    Douglas..
     
  8. SkysTheLimit

    SkysTheLimit Member

    I'm getting ready to put an expansion tank in my rig, too. Just the cheap, universal, open air one. However, my new radiator is wider than stock, so covers about half of the rear cup part of the headlight cups that protrude into the engine bay. So, basically, my question is, does it matter if the top of the universal expansion tank is roughly at about the mid-way point in height of my radiator? I know it is supposed to be up as high as possible, but just won't work out for me. how horrible is it if the top of the expansion tank is about 10-16" lower than the top of the radiator? I guess this means that where the line goes from the top of the radiator into the bottom of the overflow "bottle", the bottom of the bottle inlet and the bottom of the radiator may be very near each other in elevation. Does it not matter because the pressure is always the same in the two tanks so if it overflows, when the radiator cools it will just siphon the excess it bled off back up the line into the radiator even if the overflow is lower? Please help on the little bit of chemistry and physics involved to let me know how critical it is on where to mount this thing. Thanks guys.
     
  9. bkd

    bkd Moderator Supreme Staff Member 2022 Sponsor

    mine's at least 6-8" lower than the rad.....works fine
    Jim S.
     
  10. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Saw a really cool idea in a Hot Rod mag years ago for an overflow tank- a military aluminum water canteen mounted upside down with a hole drilled in the bottom for the hose to go in- if you ever needed to drain it just unscrew the cap.

    Just kinda sez "JEEP", doesn't it?

    H.
     
  11. jhuey

    jhuey Michigan Jeeper!

  12. cj6/442

    cj6/442 Sponsor

    wow that jeep is clean....................and white.got a side shot or build -up on here?
     
  13. SkysTheLimit

    SkysTheLimit Member

    Jhuey, for that overflow bottle, it looks like it has a drain valve on the bottom, and obviously the hose on the top. Does this work like the other "universal" overflow tanks where the line goes from the radiator to the bottom of the overflow tank, and then there is the outlet line at the top for if the overflow bottle fills too high, or does this bottle you have have the line from the radiator go into the top of the bottle, and no line on the bottom, just the drain valve? Also, how did you mount it? Thanks for the help.
     
  14. jhuey

    jhuey Michigan Jeeper!

    I just ran the overflow to the bottom with the valve open and the top just has a short hose for the vent out the top (it's tucked just out of sight on the picture, about 5" long). I took the top off and added coolant, about half way up then opened the valve and am letting the radiator do the rest. Mounting was easy it has two 1/4-20 captured nuts formed into the bottle, I think I only had to drill one hole 'cause one was already there.
     
    Last edited: Jul 16, 2009
  15. jhuey

    jhuey Michigan Jeeper!

    Bits and pieces of the build are around here. I have been building this for a while. I will write more when I have some time. You can see some stuff here,
    http://s40.photobucket.com/albums/e231/jhuey_photos/
    Joe
     
  16. dougs1963

    dougs1963 New Member

    jhuey,

    Nice collection of Jeeps.

    ...and thanks everyone for your recommendations.

    I'll get to it once I figure out my current brake issue.:(

    Douglas..