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Gas Tank Opinion

Discussion in 'Early CJ5 and CJ6 Tech' started by Tinkerfool, Jul 27, 2022.

  1. Jul 27, 2022
    Tinkerfool

    Tinkerfool New Member

    montana
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    Jul 7, 2022
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    Working on a 53' M38A1. The factory 17 gallon under seat tank is rusted out. Trying to decide between the following options:

    -Replace with new m38a1 tank -about $500. -downside Cost
    -Replace with CJ tank -about $200. -Downside amount of fuel storage and I'm not sure how the filler neck fits in the larger opening. Upside could cut out the well and make room to install rocksliders cleaner.
    -Replace with friends 15 gallon rear tank -Not sure about clearance or how far they hang down. Have seen articles on guys putting them in early CJs, has anyone tried with the M's? Wasn't sure if any of the 50cal framework got in the way? I do have the pintle hitch diagonal supports...

    Goal for the project is to keep it simple. May do axles and bigger tires eventually but plan to run 31ish tries to start. Will run jeep trails and will probably go/winch over some stuff that it doesn't have the clearance for but shouldn't be anything too crazy.
     
  2. Jul 27, 2022
    CJ51973

    CJ51973 Member

    Versailles, KY
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    Nov 6, 2009
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    I wonder if you could have that tank repaired? A good welding shop could hook you up I'd bet. Cut the bottom, blast it, weld a new bottom on?
     
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  3. Jul 27, 2022
    Rick Whitson

    Rick Whitson Detroit Area 2022 Sponsor 2021 Sponsor

    I live South of...
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    I have a 64 CJ 5, I put a new 11-gallon steel tank in it when I restored it. I use it for forest viewing, and cruising two lane roads. I never checked the mileage but when the gauge gets down to "E" it still has four gallons in it, so it takes 7 gallons to fill it, so I guess what I am saying is I have a four-gallon reserve to find gas, and it has never been a problem for me. As far as the wide opening for the filler neck I think I saw an adapter for that somewhere, or it would not be hard to make one. I like my tank under the seat out of harm's way, Good Luck whatever path you take. Rick
     
  4. Jul 27, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor

    Medford Mass USA
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    Old fashioned radiator shops used to repair gas tanks too. They would boil out the tank and solder the holes. Nearly all "radiator shops" today just sell commodity radiators and installation labor. If you look around, there may be a shop near you that can still do this work.

    You can also repair a leaky tank with "tank slosh" that coats the inside of the tank with a gas-proof coating and seals any holes and rust. I have used the Hirsch product, https://www.hirschauto.com/Gas-Tank-Sealer-_-Repair/products/4/ Worked well for me. Several different products like this are available.

    If you've got holes that you can stick your finger through, you'll either need the welding shop mentioned above, or you should be able fiberglass the outside of the tank and then coat the inside. I would not rely on the fiberglass to hold up against modern gasoline, but it would probably be ok if it were coated inside.

    The rear tank is a common upgrade for the CJs. You may be able to keep the machine gun mount, but you will have to cut out the pintle hook brace. Newer Jeeps with these tanks have extra bracing to support the pintle mount,, or just dispense with the pintle hook. Plenty of old posts on this topic here if you search. https://www.bing.com/search?q=site:earlycj5.com+rear+tank+installation
     
    Last edited: Jul 27, 2022
  5. Jul 27, 2022
    Twin2

    Twin2 not him 2022 Sponsor 2021 Sponsor

    Virginia Beach, VA
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    I would just use the CJ underseat tank
    just weld a flat piece of sheetmetal to floor
    gas filler indent . just be creative
    keep it simple
     
  6. Jul 27, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor

    Medford Mass USA
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    That would be the way to get it on the road quickly, without spending a bunch for the original-type tank.

    How much more capacity does the original tank have? The CJ under-seat tank is only 11 gallons, and it's not much if you drive any distance. I was happy to have both the rear and under-seat tank in my first Jeep.

    Looked it up. 17.5 gallons. 60% more.
     
  7. Jul 27, 2022
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    I ran a CJ5 tank in an M38a1 tub for many years. I simply cut down a treated 2x4 in the tank well so it was flush with the main floor to support the smaller tank.The filler centered perfectly in the a1 cutout. I used an CJ rubber grommet inside the a1 grommet to close the gap around the filler neck.
    I would keep the tank well in the a1 tub intact, but thats me. I have a custom aluminum tank for my A1 tub, but there are boat welding shops around me that make tanks. I didn’t have mine made, but I picked it up second-hand, though it was made locally.
    I would keep the underseat tank. A rear conversion can be done, but it requires cutting out the drawbar diagonal braces from the chassis, and a bit of other work. Then you have to cut in a filler neck, etc.
    -Donny
     
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  8. Jul 27, 2022
    Tinkerfool

    Tinkerfool New Member

    montana
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    Yeah, its a substantial difference. Will probably cruise the threads on guys that have done the rear tank conversion. Wish I was better at searching on here and getting pictures to come up. The original is in pretty rough shape. Hiring anyone to work on it wouldn't pencil around here. Good shops are months out and expensive enough I'd buy a new tank by the time they were done. Thought about putting a grinder to it to see If I can find clean metal, the inside sounds like it is full of sand -that much rust. Little concerned about sinking time and money into goop that leaves me with a still non-functioning tank. I live in Southwest MT where some of the trailheads are 140miles (round trip) to the nearest gas station. Can pack gas but not the most convenient. I may end up flat-towing to the forest service but if/when I get enough stuff done, I would like to cruise out from my driveway up to the hills and do loops without having to worry about getting back to a tow vehicle. Anyone have a guestimate on MPG...198V6 with 3speed +overdrive and 5.38 axles.
     
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  9. Jul 27, 2022
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    I would replace the tank with correct tank.
    17 gallons hard to beat from factory.
     
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  10. Jul 27, 2022
    boopiejones

    boopiejones I can’t drive 55

    California east bay
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    How rusted out is it? I’ve had great success repairing rusted out Jerry cans and fixing a leaking gas tank bung with POR15. In a couple cases where the holes were so big that the POR15 oozed out, I put duct tape over the hole to create a dam for the POR15 until it had time to harden.
     
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  11. Jul 27, 2022
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2022 Sponsor 2021 Sponsor

    Hills of NH
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    I soldered about 100 pinholes in my m38A1 tank. Extreme prep is the key.

    I've also successfully sealed tanks with fiberglas.
     
  12. Jul 27, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor

    Medford Mass USA
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    POR-15 has a gas tank sealer product that I suspect is their anti-rust MCU paint, with different packaging. No personal experience with it.

    Rather than POR-15, I would be more inclined to use a superior MCU like Aluthane. Their site touts chemical resistance, specifically resistance to gasoline. They discuss softening by oxygenated solvents like alcohol ... possibly not great for long-term immersion. Suggest you call Paul at the source and discuss if interested. https://www.epoxyproducts.com/aluthane.html

    Just to mention - POR-15 or Aluthane aren't any less expensive than the Hirsch product, which is specifically for this purpose. I followed the suggested procedure on the Hirsch site (look for the PDF) and it took all of one summer weekend. I used generic power washer detergent and two boxes of dry wall screws to clean the tank. SHake well. Followed by drying, metal etch, drying, and the slosh.
     
  13. Jul 27, 2022
    Tinkerfool

    Tinkerfool New Member

    montana
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    Keys5a sorry I missed your post somehow when I replied earlier. Thanks for the grommet suggestion (defiantly helpful if I go that route). Boopiejones/timgr thanks for your goop suggestions. I requested MSDS sheets from POR, Hirsch and Progressive Epoxy Palmers. Be interesting to see the chemical differences. I also asked Progressive if they would use their MCU on a gas tank. Curious what Hirsch uses for their etching and cleaning products. I'm leaning towards cleaning and putting the tank and seeing if it looks decent/holds fluid. If it does, I think I will try a goop and pack putty/fuel filters to ease my paranoia. If I don't get a good feeling, I think I will go with the CJ tank to get moving and testing other failures and then delete the well and add the rear tank down the road if I find It warrants dual tanks. Thanks for the help.
     
  14. Jul 28, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor

    Medford Mass USA
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    Last edited: Jul 28, 2022
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  15. Jul 28, 2022
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member

    Tantallon, Nova...
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    No it's a wholly different product, the paint is pretty much odorless, the tank sealer will make you high just being in the same room with an open can.
     
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  16. Jul 28, 2022
    duffer

    duffer Rodent Power

    Bozeman, MT
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    I'm not sure what one would end up with a custom tank these days. I bent up 0.090 5052 aluminum for my friend's Willys wagon and Bret McGinley tiged it up (https://www.facebook.com/mcginleymotorsports). Turned out really nice and I don't think Dene ended up with anything close to $500 in it.
    [​IMG]

    [​IMG]

    I made this rear tank out of 14 gauge steel for my 3B. 24.5 gallons. Pretty stout but not especially light.
    [​IMG]

    Where is SW MT are you located?
     
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  17. Jul 28, 2022
    Tinkerfool

    Tinkerfool New Member

    montana
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    So reached out to Aluthane folks they do not recommend their product for inside of fuel tanks. The SDS sheets confirm POR paint and tank lining are defiantly different. leaning towards trying to soldier/clean/line and see how it goes. Didn't compare Hirsch/POR product SDS as I just haven't had time. I can solder and clean for next to nothing and have a good idea of what the odds are it will work. Thanks for everyone's input and suggestions.

    Duffer -I'm over in Dillon. That tank looks sweet.
     
  18. Jul 29, 2022
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    Solder of brazing works much better just after sand blasting. The blasting gets rid of the rust and cleans it so with flux, the filler flows out real nice. Spotless clean makes for an easier job.
    You haven’t had fuel in this for quite a while?
    -Donny
     
  19. Jul 29, 2022
    amboynut

    amboynut Member

    Chelatchie, WA
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    I have the opposite problem, sorta. My '65 CJ6 came to me with no fuel tank other than a plastic boat tank behind the driver's seat. I prefer to keep the original configuration with the under seat tank, but the extra capacity of the rear tank is tempting. However, I'm not keen on cutting out the diagonal braces. Seems like an M38A1 tank is a good compromise even though that requires cutting out my rusted floor panel and replacing with an A1 panel. Assuming it's available. Anyone done this? I have a rotisserie.
     
  20. Jul 29, 2022
    Tinkerfool

    Tinkerfool New Member

    montana
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    Donny, "ran when it was parked." Last rear registered was 97'. So yeah its been empty for a minute. Did get it started though, running quite nice with a Mason jar tank....

    Amboynut,
    I've come across the stamped wells while trying to find a tank...they run about $120 if you wanted a drop in unit. I would think install would be pretty easy, especially if you already have work in that area...I guess the only catch is whether your rust is contained to the well area.
     
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