Welding question / structural rust

[Grumpy Northener]

Nothing much I can add here, the guys are correct in advising you how to brace the car etc, however - on the alternative names that you guys come up with over there is another - I have been been married to a very lovley Canadaian for the last ten years but OMG - the names she has for things is unreal !

[alabbasi]

Gentlemen, thanks. Brace it is before I cut the floor.

[wallacea]

Started to weld a small patch on the front nearside floor pan of a 1982 280 e 4 door and after removing the really thick white Mercedes underseal ended up at the back chassis leg looking for metal to weld to. Water had been trapped between the underseal and the metal and the metal had lost the argument. scrapped the car in disgust. Just beware! Underseal can make rust look good.

[m.thaddeus]

Sorry to hear this.
I have seen this before on a Merc, what appeared to be a sound SL with minor locaised rot turned out to be very nasty indeed. As you say, the thick rubbery sealant which is applied all over allows water to sneak in and eat the metal while leaving the paint and sealer in shape. It takes a lot of prodding with a screwdriver to find it and a lot of owners wont thank you when you do!