2003 S10 non ABS door panel repair
I hope this helps some-one with the same door panel issues.
I just tried hot glue and 2 part epoxy. Both seem to adhere very well. I will use both at each crack line - double the strength??
Scratch the substrate with course sand paper at each crack - wider that the intended repair . Wash the area out. Alcohol gets rid of any residue.
Cut small bits of fiberglass screen as a "tape" that will be bedded in the glue. The "tape" overlaps the crack about an inch each side. I did the epoxy first and after I was done I laid in the hot glue
Lay down the epoxy straddling the crack, and very quickly bed the fiberglass screen in. I cut small bits of cloth just larger than the fiberglass that I then pressed on top with my fingers. Make sure the cracked edges of the door panel are lined up and walk away for a coffee. Do only one crack at a time - so as not to disturb any other glued cracks that are setting up.
Lay down a bead of hot glue into the edges of the fiberglass - lift up the bits of cloth. I didn't save money on the glue. I used a a fair amount. Then I pressed the cloth down over the hot glue working it in towards the center and towards the epoxy. In some places I used two layers of fiberglass screen (stress areas?) with the top one larger than the first - both pushed into the epoxy at the same time.
The cloth keeps any glue off your fingers and allows you to work fast. The cloth can be any non stretchy material - cut up bits of old jeans works. Fiberglass screen was the left over roll from a screen door repair.
You can also tape the outside together to keep any possible drips in in the crack. But that also makes it harder to make sure your edges are lined up.