Disolving undercoating....help!
 

I have replaced the activated carbon container in the rear right wheelarch. I treated some rustspots with a product simular to POR15. But now I looks like the PVC-undercoating is disolving or working like a sponge(picture). I've removed the loose parts What to do next?

Thanks,
Kees.http://forums.pelicanparts.com/uploa...1073224975.jpg

try scraping the undercoating to see if it has lifted from the surface. I doubt that it has. Most likely its now comprimised but hard as a rock and stuck fast to the surface. I would suggest that you remove it. I braded cup wire brush on a 4" (100mm) angle grinder works well. Take the aread to bare metal and then treat with your rust proofing paints. While your at it, hit any spots on teh chassis that show cracked undercoating or rust. then just shoot undercoating on top of the newly painted and protected area.

uncercoating removal
 

I would remove the undercoating. I have been using a propane torch and working a small area until I see a reddish flame come off the surface as the torch hits that area. Basically, the undercoating is smoldering. A putty knife easily scrapes it off then. There are many areas where small patches are left. I then used my angle grinder with a knotted wire wheel. Cleans up real nice.