W126 Trunk Seal + Rust Repair - PeachParts Mercedes-Benz Forum

300SD81 · #1 11-28-2012, 04:25 PM

In the middle of changing the trunk seal on my 300SD. I've wire brushed out most of the rust, but theres some in the seam where the 2 pieces of metal join together that I can't get to. Anyone have any advise on how to remove it? Or should I just smother it with POR15 and hope for the best?

Also, how the heck do I get this rubbery sealant off? Its so soft that wire brushing or sanding just melts it and moves it around, and mixes it into the paint. I tried rubbing it with my fingers, and it kind of works, but its going to take days and wear my fingers down to the bone!

Chad300tdt · #2 11-28-2012, 04:30 PM

Try some denatured alcohol or spirits to clean off the rubber. Then use this to fix the seal ridge.

PORPATCH-POR-15 Inc.

LandYaghtLover · #3 11-28-2012, 04:34 PM

I learned about Xylene at work. This stuff cleans thing very, very well. Removes oil stains nicely too.

Diesel911 · #4 11-28-2012, 04:35 PM

The rubbery Sealant might come of if you find a piece of Plastic to use as a Scraper.

If you cannot get at some of the Rust but you can degrease so it is nice and dry you might consider one of those Rust Converter type stuff that come in a Plastic Bottle. AutoZone and other places sell it.

It chemically converts the rust into something else and has a surface that can be painted.
UV light is bad for the Rust Converter after it dries all it needs to be top coated but also since it is under the Trunk it is not going to be exposed to much light anyway.

The one I used is about $8 a Bottle. If you want it to last longer do not dip your Brush/Applicator inside of the Bottle. Pour a little into a Glass, porcelain or enameled Cup and use that; putting the Cap back on the Container as soon as you can.

Chad300tdt · #5 11-28-2012, 04:46 PM

Quote:

Originally Posted by GermanStarAuto

That stuff is awesome. You can't beat metal though.

That's true, but welding will burn the paint in that area where the POR patch will do the job without the need to prep for welds or deal with any burnt paint.

300SD81 · #6 11-28-2012, 04:49 PM

I don't think welding the seam is necessary, its open all the way across, not just where its rusted out and I can't weld anything less than 1/4 in anyway.

The main problem is its rusted out between the 2 pieces, and I can't really get a dremel in between. I'm considering cutting out a chunk of the upper piece, brushing off the rust on the lower piece, and just filling it back in with fiberglass and POR15. How strong is this stuff after it hardens? Can it be used to form the edge where its only 1/16 in thick?

Graham · #7 11-28-2012, 08:16 PM

Quote:

Originally Posted by 300SD81

The main problem is its rusted out between the 2 pieces, and I can't really get a dremel in between. I'm considering cutting out a chunk of the upper piece, brushing off the rust on the lower piece, and just filling it back in with fiberglass and POR15. How strong is this stuff after it hardens? Can it be used to form the edge where its only 1/16 in thick?

The POR15 really has little strength in itself. But if used with reinforcing, the composite that results will be strong. I have used lightweight glass cloth when making patches and have also used polyester window screening to build up several layers of trunk floor where there was nothing left but rust (That was 20+ yrs ago on my SL and it's still good!)

Is there a way that you could pry the metal apart slightly, or perhaps use a knife to open up some space? Then use something like adhesive aluminum tape to form a raised lip so that you can get the POR to run into the space. POR doesn't mind that there is rust there but using rust converter first might be an idea. Only problem would be if moisture can get to same space from other side. But you will nevertheless be way head.

300SD81 · #8 11-28-2012, 08:32 PM

After more inspection, I've found significant amounts of rust in the channel behind the seam. Looks like I'm going to have to cut it open clean it. I'll cut the upper metal piece in a rectangle and epoxy it back in backwards so the rust damaged side can be completely covered. I don't see any way to weld it in place without introducing more places where it could rust...