OK, I've wirebrushed the rust away (first two pictures) and then ground most out with a small grinder on a Dremel tool (last two pictures).

There are still small rust pits in the metal and some rust in the weld joint at the 12 to 3 o'clock positions. The POR15 is supposed to neutralize the rust in the pits - right? What about the rust in the weld joint? Or should I grind out the rust in the weld - I assume that it wouldn't take much more grinding to remove it. The instructions with the POR15 state that it is OK to have some rust remaining but I'm not so confident if the rust is migrating through a seam or joint. I do want to do an excellent job so that I can rest comfortably with my results.

It also looks like that I will not need the POR15 Silver as I didn't have to grind out too much. However, I am thinking about blending the repair to the existing primer/paint/undercoating - is this doable with an excellent result or will look it like a patch? This is the part that I'm worried about as I want to do a "perfect" job and not have to re-visit this anytime soon. I changed my thinking because it looks like the weatherstripping between the rocker panel and door is glued on and may be a big hassle to remove or replace in order to permit a thorough repainting of the rocker panel. Same concern goes for the rubber pads beneath the jack posts.

My other concern is the rust inside the tube. The tube corroded as deep as the plugs. Based on your previous comments and from what I can see inside I think that the best action is to use POR15 black paint after I brush/grind out the rust. However, I am concerned with the compatibility of the POR15 and the MB coating inside (is this WAXOYL?) as well as blending the two coatings so that the tube is full protected inside. Your comments?

Again, thanks for your tips and I'll keep posting my updates with pictures.

Regards,
Paul
1989 300E

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