Water leaks in frame member....? - PeachParts Mercedes-Benz Forum

deerefanatic · #1 08-21-2006, 10:04 AM

Hi all, as I might have mentioned before, I just finished work on the driver's side floor of my SD. The floor and sidewall had a bunch of rust holes, and the fram member running from the B-pillar crosswise and into the engine compartment (part of it is directly under the brake pedal) was rusted in two. I got this all welded up and the holes patched. Got everything sealed (or so I thought) and decided to run water with a hose around to check for leaks.

What I found was that if I run water into the area where the fuse box and brake master cylinder are, I ended up with water (lots of it!! ) inside that frame member (I was smart enough not to weld a top on it.........that way I could monitor it for a while.) I could see it dribbling in a constant stream from the top of this member, just past the firewall. I reached my hand up in there and there are two holes in the top, side by side. Not rust holes, but holes that are machined in the metal, for like body plugs to go in. But they are bigger than most of the holes for body plugs.

My question is, are there supposed to be plugs in those holes, or are they the drainage points in the system for the fusebox area? If they are the drainage points, then I'll have to make a new drain hole in the metal I welded in, as that's the lowest point in the frame member, plus I would think that I would need to treat the inside of that frame member with some rust & corosion protection (probably 3M rubberized undercoating, great in non-abrasive applications like this......)

If I need, I can take pictures to help explain this better...

deerefanatic · #2 08-21-2006, 09:33 PM

maybe these pictures will help you guys see what I'm talking about.......

Nate · #3 08-21-2006, 10:38 PM

i see way too much bondo/fiberglass in that picture... did you weld, or did u do otherwise?

deerefanatic · #4 08-22-2006, 09:13 AM

Yes, all of the frame member is welded (Inside AND out) and sealed with Martin Senour Hard Seam sealer. I used really heavy (about twice as thick as original) galvanized sheet metal for that frame member. I then pop-riveted sheetmetal into the remaining holes and used USC Duraglas (recommended by a pro body guy I know, it's the stuff he uses.....) to seal and add rigidity.

For a strenght analysis, I pounded on it with a hammer to beat of some sharp edges, and there was no sign or cracking, delamination, etc. In fact, that stuff seems stronger than the steel used as a backer under it!

I then used more seam sealer under the car to seal all the seams and gave a generous dose of 3M Rubberized spray-on Undercoating......

But, I have this leakage problem, that's it........

deerefanatic · #5 08-22-2006, 02:30 PM

I really could use an answer here......It's supposed to rain tonight!

Anyone?