Hello,
I'm looking for suggestions, on repairing a plastic fuel tank, that has about a 4 inch "C" shaped crack.

My first inclination, was to drill a small hole at either end of the crack, to minimize any future migration (though, this is from a '75 Dodge Motorhome, and none of the various goops applied through the decades has held up).

Can I "plastic weld" it myself, using a powerful soldering iron (I have one for use w/ installing copper roofs). Any idea what sort of black plastic that tank is made of (and any chance I can just purchase the filler rod and take my chances)?

Anyone in NJ (central) that knows where I could take the tank to have it welded if I can't DIY.

Any recommendations on an repair goop I could apply, that'll actually stand the test of time (sure is easy enough to slather something on, but inevitably it gives way). While i have the tank out, I want to just do this one final time.

(I figure I'll backfill the tank w/ water, just to eliminate any ignition potential, should I take my soldering iron to it).

Thanks.