Anyone ever fix this? 1/2 of the rear floor pans in my "new" 85 300D w/470k miles are rusty and like paper. I have never welded or worked with metal like this before, but I think its time to try! How hard is this?

John

83 300D 210k
85 300D 470k
87 300SDL 245k

Oh no, body cancer, run for your life!!!!!!

Depends upon just how bad it is -- you will need to fix the leak, and it is often the seal on the rear window.

I'm not sure about the 123 -- my brother and I are nearly done with the welding (and endless triming and forming of sheetmetal) on his 115 with missing rear floorpans.

The rust is a result of interior water, usually contaminated with salt unless you can find serious damage to the undercoating. My brother's 300 had perfect undercoating and no floors in the back. My 220D has no floors in the front and had perfect undercoating when I bought it.

This is a major project. You will need a wire feed arc welder (one of the 110 jobs is fine) with inert gas accessory if you can get one -- it blows argon/CO2 over the actuall welding arc while it is on. A set of body hammers and dollies will be very useful, along with a set of right and left handed metal snips.

Be prepared to replace the floorpans in the rear -- replacements are available -- and probably quite a bit of other stuff in strange places. The floorpans can be snipped out to good metal and the replacements butt welded in (you can also lap weld, but that is more trouble once you figure out the butt weld. You will also find holes under the seats in front, probably in spots all other the front floor pans, and in the trunk, especially if the fender drains aren't any good.

I'm not sure I'm going to do the 220D -- we are just about sick of cutting and welding on the 300D.

You will get a nearly new car when you are done, though, so it might be worth it to you.

There is no percentage on having this car restored -- the price when you are done will be considerably less that the cost of the work. Save that for an SL or 600.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Ok, I know this sounds crude, but I have never welded before, here is what I am thinking:

Cut out all the rotted metal (approx 1ft x 1ft square on each side), get a sheet of galvanized steel, silicone sealant and bunch of sheet metal screws and get to work. I am not looking for a professional job, as long as people can sit in the back seat and keep water out, my work will be hidden under carpeting anyway.

I am thinking of doing the same to my 300d 76. Galvanized metel is hard to weld.

Pop rivets will probably work better -- they pull the pieces of sheetmetal tighter and won't pull loose so easily.

You will probably have to form the sides of the replacement piece up -- the rot will extend up into the sides of the floorpan.

Scrape ALL the free rust off, and treat any rusty metal with several coats of conversion primer -- Auto Zone and PepBoys sell it. This converts any iron oxide to an iron phosphate complex and greatly slows down the rusting process.

Get some good undersealant (rubber, not the sprayon ashphalt stuff) and coat about 1/8" thick from the bottom when you get done. A coat on the floor inside won't hurt, either.

As long as you can find solid, unrusted metal to put the poprivets in, you will be all right. Make sure you coat both sides of the rivets with undersealant, though, otherwise you will get galvanic corrosion and they will fall out pretty fast.

476,000 miles, what a car!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!