I “think” these tanks may be made from polyethylene. And nothing likes to stick to that low surface energy type of plastic. In fact if you want glue to stick it has to be special just for it. I might be wrong on the plastic type, but is sure acts like it.
Now to the leaking plug. That is probably a 3/8” NPT drain plug.
This is a carbon steel one, could not find a brass one quick, but if it is a 3/8 NPT plug then odds are it has a 5/16 hex
Yes taking it out and putting fresh Teflon tape on and putting it back in is the fix. Actually even tightening it up may stop the leak. Heads up on that fitting, the metal plug wins and if you get carried away the plastic will loose…. The plastic just keeps flaring out.
I’m trying to think what you might have around the house that can be used as a make shift hex key. If you happen to have a small hex bolt and 2 nuts that fit it, jam 2 nuts together on the bolt, turn it around and put the head of the bolt into the plug hex. Then turn the 2 nuts as one.
A 5/16 hex head screw is like for a number 12 or 10 screw (aka 3/16”) odds are not good the normal home owner has them laying around, but who knows.
OR you can make a hex key. Take a 3/8 bolt, or a 1/2" bolt, a file and file the end to a hex. A 3/8 bolt is more common to have around.
Or buy a hex key itself.
Hope this helps
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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