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`70 CJ5 gas tanks?

Discussion in 'Early CJ5 and CJ6 Tech' started by ShaggieSAM, Jan 7, 2012.

  1. Jan 7, 2012
    ShaggieSAM

    ShaggieSAM New Member

    Forest, VA
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    Dec 27, 2011
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    I will be removing the gas tank on my `70 CJ5 this weekend and am anticipating rust in it, but hopefully just old fuel. I have done a few searches and found only poly replacement tanks and no steel. So this ponders a few questions/options that I could use some tips/advice on.


    1.) I would like to keep most originality to the Jeep, and don't have the funds to restore to original, also with it being damn near impossible. I have a `71-72 undercarriage donor tank that I could use that appears to have some sort of method of hanging it. Would I need to make a bracket and does anyone have pictures/tips, etc, etc. for me in how to do it. Also, what is a good way to clean out this donor tank?

    2.) Anyone have experience using these under seat poly tanks are are you pleased with it?

    3.) Are steel replacements available?

    4.) When I remove my current original tank, how can I clean it out (what materials) to see if it is in good enough shape. I just rebuilt my carb and I would hate to clog it up again.

    Thanks!
    Matt
     
  2. Jan 7, 2012
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    Some pics of the rear tank I put in my 70 CJ5

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    To put in the rear tank, there's 2 diagonal cross braces that have to be cut out of the frame-also if you have the stock drawbar/trailer hitch you'll have to modify the braces or replace it with the 71 up style. You may also have problems with the exhaust. My muffler was right where the tank needed to go, so I had a whole new evhaust built from the y pipe back.
     
    Last edited: Jan 7, 2012
  3. Jan 7, 2012
    ShaggieSAM

    ShaggieSAM New Member

    Forest, VA
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    That looks to be a bit difficult with the body on. My tank looks very similar to that one and has two metal straps like your single one with holes across the length of the straps. Is it mounted by the straps or buy the skip plate holes?

    I'm not worried about the exhaust as I may do side pipes, not sure yet.


    Another question is, did/do the original tanks have sending units? If so, electrical?


    Thanks for your photos, I will bookmark this for reference. Oh, just noticed your in CO, my `70 was originally found abandoned somewhere off an old fire road in CO and re-titled and repaired and now its mine!
     
  4. Jan 7, 2012
    colojeepguy

    colojeepguy Colorado Springs

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    It's a tight fit with the body on but its doable. Both tanks have sending units. My tank mounts using holes in the skidplate-sounds like yours might be different.
     
  5. Jan 7, 2012
    noahlon

    noahlon Old Fart

    Pine Ridge, AR
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    Dec 22, 2010
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    I replaced my tank with the poly and have had no problems.
     
  6. Jan 7, 2012
    theotherjmmy

    theotherjmmy Member

    Austin, Texas
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    What he said-tank fits with a little fiddling to the strap and is a quality piece.
     
  7. Jan 7, 2012
    ShaggieSAM

    ShaggieSAM New Member

    Forest, VA
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    @ noahlon: Did you use the same/previous sending unit or did you replace that as well? How many gallons does it hold, I am not finding any information on that from the Poly tanks that I have been searching.

    So whats the major pros/cons of converting to undercarraige?
     
  8. Jan 7, 2012
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Design of the 70-71-72-73-74-75 rear mounted tanks are all the same, except for the smog plumbing. Does your Jeep have the vapor recovery expansion tank under the right rear fender.
     
  9. Jan 7, 2012
    ShaggieSAM

    ShaggieSAM New Member

    Forest, VA
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    Hmm, I don't know. I would have to check it when I get home, I am currently on call and stuck at the hospital inbetween surgeries.

    Would this make a difference?
     
    Last edited: Jan 7, 2012
  10. Jan 7, 2012
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Well, pretty sure that the 71-72 tanks are all the same. These have vapor tubes that come from each corner of the tank and go to an expansion tank under the fender. Lots of hoses. I know that '72 had vapor recovery from the factory, but a '70 or '71 may not have. If not, the vents would be absent or plugged, and the Jeep would have a vented gas cap. A Jeep with vapor recovery needs a sealed gas cap.

    The later tanks 73-74-75 have an expansion chamber built into the tank, and use a liquid check valve under the left rear fender. Pretty sure all these Jeeps had vapor recovery from the factory.

    The size, shape and brackets are the same for both versions.
     
  11. Jan 7, 2012
    ShaggieSAM

    ShaggieSAM New Member

    Forest, VA
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    I don't recall seeing any extra vents or hoses on the corners of the tank.

    I'm not sure I like the idea of cutting another hole in the tube to accomodate the new filler hoses. I like the fact that a visual difference in a `72+ CJ is the side filler neck at the driver side, which of course will stay despite a conversion.

    Thanks again for the replys.


    Anyone want to takle the question regarding cleaning out my current tank?
     
  12. Jan 7, 2012
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Mmm... huh?

    All the rear tank Jeeps from this era have the filler neck on the right rear, facing behind the Jeep. The side-fill only arrived with the Wrangler, I believe.

    For many years the tank was under the driver's seat. Then in mid-70 it moved to the rear. The design changed a little in '76, using straps to hold the tank to the skid plate instead of the tank bolting directly to the frame.
     
    Last edited: Jan 7, 2012
  13. Jan 7, 2012
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    I cleaned and sealed the CJ-6 tank. I used the Bill Hirsch tank sealer and followed their directions. I put two boxes of 1" drywall screws in with the tank cleaner, for agitation. Then shake-shake-shake. The screws are easy to remove later dumping most of them through the sender hole and fishing out the rest with a magnet on a stick.
     
  14. Jan 7, 2012
    theotherjmmy

    theotherjmmy Member

    Austin, Texas
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    Or you might take it to a radiator shop to be boiled out and then treated with whatever you decide on. Probably cost more than the method Tim referred to though.
     
  15. Jan 8, 2012
    noahlon

    noahlon Old Fart

    Pine Ridge, AR
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    The 11 gallon tank I bought over a year ago was listed for the 225 V6 and sending unit was included. Cleaned and rhinolined the floor, set the new tank in used the factory strap, hooked it up and working great! Just had to cover the holes under the tank where the factory fuel outlet was and drill a new hole next to the tank for the fuel line.

    http://www.cyberjeep.com/cj/pr/gas-tank-poly-55-69-under-driver-seat


     
    Last edited: Jan 8, 2012
  16. Jan 8, 2012
    04sd2

    04sd2 Member

    Lehigh Valley, PA
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    Eastwood sells some gas tank kits. Cleaner, rust remover, sealer. Eastwood.com.
     
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