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poly gas tank mod how-to

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by bp71k5, Feb 27, 2007.

  1. bp71k5

    bp71k5 3/4 ton status Premium Member

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    Hi,

    I thought this might be useful to someone else who has the problem of hooking up the gas filler neck after replacing the gas tank in a first gen with one of the poly (plastic) tanks you get as a replacement. With the metal tanks, the instructions say that you need to transfer the old filler neck from your existing tank onto the new tank.

    The reason you need to transfer the filler neck is that the place that they put the filler inlet on the new tank is in a spot where there're no room to hook anything up to it. Specifically, the neck inlet on the tank is placed right where the rear horizontal support is located. There is simply no way to get any kind of hose on there if you do not have a body lift. The first pic shows how cramped it is.

    I thought about cutting the neck down and trying to use a section of the old filler neck with a small rubber pipe to hook it up( as Burt 4x4 suggested) but realized if that it would still be very tight in there without any kind of body lift.

    So I decided to try and bend the inlet away from the supports enough to get the hose clamped onto it. By looking closer, it only needs to bend about 45 degrees to the rear of the truck and a little downward.

    I decided to try heating the inlet nozzle and bending it with a pipe to the direction I needed. To keep the inlet opening round, I placed a hose clamp on the end, but not very tight.

    I then used a heat gun from Sears set at ~650F to slowly heat the inlet and surrounding area for about 10 minutes until it seemed to bend easily without over stretching anything. Most of the bending happended on the surrounding area of the tank and not on the actual inlet portion.

    Once it would bend the amount I needed, I let it cool down while I held it in place. It had a tendancy to want to creep back to the original location, but once it cooled down enough, it would stay there.

    Once it was back in, it was now much easier to get the filler hose clamped on and the hose routed pretty easily without kinks or rubbing on the frame.

    Feel free to steal the idea for your own uses.

    gastank.jpg

    tank.jpg
     
  2. Yukon Jack

    Yukon Jack 1/2 ton status

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    Thankfully I was able to reuse my stock tank but this will undoubtably help those who are forced to switch. Really too bad the company doesn't make a tank that actually works right out of the box.
     
  3. bp71k5

    bp71k5 3/4 ton status Premium Member

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    Yea, I'll have to post a pic of what my original tank looked like. It looked like a boulder caved it in from underneath. I'm surprised it didn't leak. I would have left it if I could have got the gas guage sender unit working. I need to post a pic of how it ended up too. I drove it around for a few hours and it seems to be fine.
     
  4. 2wdBlazer

    2wdBlazer 1/2 ton status

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    I hope you have a skid plade because I would never buy a poly tank. Wait till you meet that same boulder!!!

    I have also heard of the poly tanks sagging and warping in severe heat cities. Like 105 outside or something.
     
  5. 54inches

    54inches 1/2 ton status

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    Are these MTS tanks we are talking about?

    I was just about to buy one tonight, but I am going to wait until I hear some more reviews...
     
  6. bp71k5

    bp71k5 3/4 ton status Premium Member

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    Yea, I do plan on having one fabbed up later.

    I think I've heard that, but the straps they have would seem to not allow much sag. I'll re-post if I ever find anything like that.

    I bought mine from brotherstrucks.com, but I think they are just resellers for MTS. They look identical. It seems to be working just fine, but if you do not have a body lift, you will HAVE to do something to get the filler neck hooked up right. The other issue is that it is tough to find the correct size rubber hose to replace the filler neck. The catalogs say 2" is what was used, but it's actually 1-3/8" ID hose. I had to special order it since none of the parts places here had it. You will need about 3 feet of it if you replace both parts of the hose.

    If I had to do it again, I'd get the metal one from LMC and just re-solder the old filler neck to the new one. This one is ok, but required lots of fooling around I'd rather not have done.
     
  7. MNorby

    MNorby 3/4 ton status Premium Member GMOTM Winner

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    any news on how the tank works yet?
     
  8. smalltowncowboy

    smalltowncowboy 1/2 ton status

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    im glad the one im picking up has a fuel cell in the bed area. no need for a skid plate, and wont get in the way of my shackle flip.
     
  9. MNorby

    MNorby 3/4 ton status Premium Member GMOTM Winner

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    the prob I have with a cell is I have a softtop and would be a pain to fill it every time.
     
  10. bp71k5

    bp71k5 3/4 ton status Premium Member

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    It's working just fine so far. One thing I am watching is the filler neck may not have been bent far enough so the rubber filler neck is slightly rubbing on the body mount. I can make it not touch at all by pushing the tube over with my hand.

    I may try grinding the corner off the body mount bracket. (it's a pretty small amount) or trying to fasten the filler tube a little so it doesn't rub.

    One thing I do wonder about is that the plastic tank has nothing to fasten it to the frame front-back. The metal tanks have some tabs that go through a few holes in the frame to keep it from sliding forward or backward. Mine doesn't look like it's moved at all so maybe it's not a big deal. I may fab up an L bracket that bolts to the frame to add some insurance.

    If I had to do it again, I might get a metal tank instead. I'm just not sure how you would modify the filler neck to fit, but it doesn't look impossible. If you have even a small body lift, this would not be much of an issue.

    You probably won't go wrong either way.
     
  11. MNorby

    MNorby 3/4 ton status Premium Member GMOTM Winner

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    I have a 1.5" BL and pretty decent room to run a filler I think
     
  12. MNorby

    MNorby 3/4 ton status Premium Member GMOTM Winner

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    do you have any pics of how it hangs down and mounts and all?
     
  13. bp71k5

    bp71k5 3/4 ton status Premium Member

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    with a 1.5" BL, I think you could use a new metal tank and either solder your old filler neck tube onto the new tank, or bend the new short metal neck towards the back of the truck a little. I haven't actually seen the metal tanks so I can't say for sure, but I'd think if you find a steel pipe that fits inside the neck, you could use that to bend it over enough to work without kinking it.

    The body lift just makes it do you don't have the bend the neck downward as well as backwards.:doah:
     
  14. MNorby

    MNorby 3/4 ton status Premium Member GMOTM Winner

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    I see. I have a metal tank but its junk so gotta decide what to do. thanks
     
  15. bp71k5

    bp71k5 3/4 ton status Premium Member

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    Here's a couple of pics. It sits about level with my tailpipes and the same height as the stock tank (note, the bumper is off because I'm getting one of those hidden class IV hitches next week). I also included a pic of how the new rubber filler tube routes. The red circle is where it's touching the body mount a bit.

    Blazer1 084_640x480.jpg

    Blazer1 086_640x480.jpg
     
    Last edited: May 20, 2007

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