So my '93 XJ I sold about five months ago had a strange problem... it was rusting everywhere. Hah, yeah, real strange. An XJ rusting?! Unheard of!
Anyway, that rust bucket is long gone; no more 2' rust hole in the PS front floor, no more rusted-through rear rockers, etc.
But now my new project vehicle, a '93 2-door XJ... well, I wanted to explore an idea, but I'm not gunna do it until I run it by a few of you guys. I thought I might vacuum-out all the rockers and the inside bottom of the rear quarters (thus removing all the loose rust, dirt, debris, silt, etc.) and fill them with spray-in expanding foam insulation (tan foam crap in a can). The idea here is that since that crap is as tacky as can be, seals really well, and is oil-based, it should seal-out moisture and therefore rust, right? I thought spread around some POR-15, let it dry, then spray in the expanding foam, filling the not yet rusted rockers as well.
Before everyone shoots this down, consider this. . . I took a look in both my '95 Audi 90 Sport, and my '03 Audi Allroad, and BOTH have this SAME expanding foam down in their rear quarters (down in the rocker section). Both Audis are 100% rust free, and the stuff HAS TO insulate against road noise to an extent as well.
Having read the Audi tidbit, any thoughts? Has anyone done this before? Good experiences? Bad experiences?