Date registered: Jan 2006
Vehicle: 73 280SE 4.5, 71 300SEL, 03 BMW Z4, 72 Fiat 850, 80 Triumph TR7, 85 Porsche 911
Location: DC Area
Mentioned: 1 Post(s)
Quoted: 103 Post(s)
The first Benz I bought myself was a 114, with the same issues. After removing the seats and carpet, I used a Makita cutting tool to cut the rust out. The bottom looked like swiss cheese.
IFrom the local home improvement store, I bought sheets of same thickness metal and cut patches to fit, and welded them in. I did the same on a 108 that I still have.
If you don't have a welding rig, try making all the patches on one day and renting the welder for the next day. Well within the realm of inexpensiveness.
After patching, grind down the welds, spray on a couple cans of primer/sealant, and use rubberized sealant on the weld seams.
I also used truck bed coating on the underneath, to protect the new metal.
A new Makita will be about $60, cutting disks $5 per, sheet metal about $50 or so, spray paint $7 per can, truck bed coating at $40 per small can. No idea how much renting a welder would be...