putting a blind drain in poly tank... BEEN DONE??

I have a polyethylene gas tank in my 41 ford. I drilled a small hole in the bottom of the tank to drain it completely.

I removed the tank, made a small repair to the the trunk floor and am ready to replace it. I would like to put in a petcock of some sort to facilitate draining the tank in the future if necessary.

There is not enough room to put a compression type fitting in, as the only access is through the sending unit hole, too small for most human hands.

Have any of you come into a solution for this particular problem? Any help would be appreciated.

I have thought of a "nut sert" type of female for the tank, and simply using a bolt to finish it off. I don't know if this is a viable solution or it will leak.

Thanks, Gary

 

Why not use a self tapping screw with a neoprene washer. I have done this and it held up perfectly. If you ever need to drain the tank just take out the screw.

 

I've used the automatic transmission drain plug kits. They are an insert with a nut on the outside and tapped for 1/8th pipe on the inside.

 

Use a bulkhead fitting, the type with a nylon washer or o ring. They make them specifically for that use. Any decent fitting place will have them. It's the same thing they use for outlets on plastic fuel cells.

 

i used one of these truck valve stems, i removed the rubber and replaced it with a slice of rubber gas line, for mine i barbed the stem by putting in my drill press and fileing in a couple barbs, i fished it into my tank by running a piece of wire up the hole and out the filler, i slid the valve stem on the wire and it slid down to the hole, not sure how a shut off could be made to attach but should not be hard to figure out.

 

Genius, I love it. The only question is whether the rubber will withstand today's fuels.

 

go to a marine store, you will find an array of possibilities

 

No help for your problem today, sorry.
I lost track of the exact number of fuel tanks that I've drained, but ill guess that its over 50. I have never had to drill a hole in the bottom of one. I've used electric pumps, siphons, compressed air, leaf blowers, shop vac on the blow side, old hand pumps, jiggle siphon pumps, and probably a few I have forgotten.

So why did you drill a hole in the tank ?

 

This... Make a long wrench out of a piece of flat stock and tape the inner fitting to it. Assemble, tighten, enjoy leak free fitting with an easy to adapt to threads.

 

Yeah....

Now that it's too late, they make an "explosion proof" bulkhead that is used in the electrical industry. A lot like the AN type shown above, but they have 1/4" NPT internal threads that you can screw a drain petcock into.

The idea of fishing it down a piece of wire is brilliant. Use a long piece of TIG filler wire (STEEL!) and put a washer on it above the bulkhead, then bend a loop above the washer so you can PULL down on the fitting to get the seals to go into place. Normally you can hold them from the bottom well enough to get the seal nut tightened.