the spirit is willing....but the body...

[JamesDean]

On my dad's green 300SD:

Looks like I've got some more repair work to do... Not really sure what this area really is..

[pawoSD]

Yikes, my guess is that if you remove all the undercoat along there, its probably a LOT worse inside.

[Stretch]

That's what happens when water gets into the front of the car.

The three most likely sources are that water leaks from the windscreen, sometimes down the outer side sunroof drain tubes, and the bonnet / hood spring pockets into the front foot wells.

If water settles on a little bucket-like ledge on the side of the bulkhead on the outer side of the foot well it eventually leaks into the sills.

Water travels along the whole length of the sill and usually makes its way into the section close to the front mounts of the rear suspension sub frame too so check there.

The joint between the sill and the floor pan is spot welded - this joint by the very nature of the construction is unprotected - no seam sealer here! So rot takes hold quite quickly.

[JamesDean]

Hmmmm I wonder how salvageable this situation is.

I would put it up on a rack and just rip off all the undercoating in that area and see whats going on. I'd put on new sills and fix whatever else.

Alas, I do not have a lift.

Ideally...I would find a nice healthy SWB W126 with bum motor/trans and dump the 300SD's drive train into it. Both this SD's engine and transmission are in quite good shape. I just dumped like $600-800 into new motor mount, turbo rebuilt, intake/exhaust reseal, oil pan reseal, turbo drain tube replacement, new valve cover gasket, upgraded alternator/wiring, and a freshly tested and balanced set of injectors.

[DieselPaul]

None of that looks structural. I'd do what I did with the 190D 2.5. Great drivetrain and great interior but we are totally fine with the idea of ultimately scrapping the shell. So I got out the trusty harbor freight welder and my metal forming tools and patched up the bottom as best I could. Keeping water and salt out of those non structural holes will give you years and years until it becomes structural. Then just undercoat the hell out of it.

those aren't proper fixes but if you've resigned yourself to ultimately changing shells, you can put it off for 5 years that way.

[JamesDean]

Originally Posted by DieselPaul

None of that looks structural. I'd do what I did with the 190D 2.5. Great drivetrain and great interior but we are totally fine with the idea of ultimately scrapping the shell. So I got out the trusty harbor freight welder and my metal forming tools and patched up the bottom as best I could. Keeping water and salt out of those non structural holes will give you years and years until it becomes structural. Then just undercoat the hell out of it.

those aren't proper fixes but if you've resigned yourself to ultimately changing shells, you can put it off for 5 years that way.

That's what I thought too, none of it looks structural.

I was in that situation about 4 years ago too actually. I had rust all over the body. I patched up a good amount of it.

Here are some inspection photos from 2 years ago, 2 years after the job.
300SD Rust Analysis ~2 Years Later - Imgur

I could--for the short term--do the same procedure. Wire wheel and clean off a good few feet around that area. Weld in some heavy sheet metal. Spray some internal frame coating stuff. Undercoat the hell out of it. Done.

Probably a few days work. Would be nice if I could use a lift to do it.

[snorider]

"I could--for the short term--do the same procedure. Wire wheel and clean off a good few feet around that area. Weld in some heavy sheet metal. Spray some internal frame coating stuff. Undercoat the hell out of it. Done. "

That's the only solution afaik. and it sounds like you've got experience doing it. Unibody construction is very strong as long as you keep it rigid, and rust repairs do just that. Good luck.

[funola]

I have to comment on your pic. Is that a block of rubber between the jack stand and the body? If it is, it's way too thick. Next time, you may want to consider using a piece of plywood instead.

Maybe it's the angle the pic was taken from but that jack stand placement looks quite precarious.

[pawoSD]

Originally Posted by JamesDean

Hmmmm I wonder how salvageable this situation is.

I would put it up on a rack and just rip off all the undercoating in that area and see whats going on. I'd put on new sills and fix whatever else.

Alas, I do not have a lift.

Ideally...I would find a nice healthy SWB W126 with bum motor/trans and dump the 300SD's drive train into it. Both this SD's engine and transmission are in quite good shape. I just dumped like $600-800 into new motor mount, turbo rebuilt, intake/exhaust reseal, oil pan reseal, turbo drain tube replacement, new valve cover gasket, upgraded alternator/wiring, and a freshly tested and balanced set of injectors.

I have a running driving 420SEL in good shape with an engine that needs a timing chain and guides soon (or to be swapped to diesel ) Virtually no rust on the car, and it still drives fine. Its for sale cheap!

[JamesDean]

Funola,

Can you add an "l' to the end of the file path on that image? It will force it to the large thumbnail size.

---> i.imgur.com/dRiKDl.jpg

Its an incredibly massive image!

It was quite a long time ago for my memory..but that rubber block is the factory lift pad. The stand is poorly placed as you indicate. Not sure why I let that fly.

Originally Posted by pawoSD

I have a running driving 420SEL in good shape with an engine that needs a timing chain and guides soon (or to be swapped to diesel ) Virtually no rust on the car, and it still drives fine. Its for sale cheap!

That might not be a bad move. I mean with the SD here I would have all the parts needed to be swapped.

Hmmm.

[Junkman]

Remove the undercoating and see how extensive the damage is. A friend of mine is an old school bodyman who can fab the repair. I have a 78 Datsun Z that he replaced sections of the floor pan on. The repair is hardly noticeable after he hit it with seam sealer and paint. See how long a trip it would be to bring it down here.

I also have a late 84 SD that I've been scalping parts from that may be for sale. It depends on whether I cut the back panel out to fix my 85.

[funola]

adding an "l' to the end of the file path resulted in no pic.

Are you saying that rubber block is OE from Mercedes?

[JamesDean]

Originally Posted by funola

adding an "l' to the end of the file path resulted in no pic.

Are you saying that rubber block is OE from Mercedes?

Lower case L at the end of the file name just before the extension should do the trick:



Yes that rubber pad is factory. Its used on the back lift points of the W126, at least first gen. 2nd gen has round shaped ones. I think the 201 and 124 have round ones too. The rubber pad thing has a center pin/mount that goes up into the chassis directly under the jack point.

[pawoSD]

Originally Posted by JamesDean

Funola,

Can you add an "l' to the end of the file path on that image? It will force it to the large thumbnail size.

---> i.imgur.com/dRiKDl.jpg

Its an incredibly massive image!

It was quite a long time ago for my memory..but that rubber block is the factory lift pad. The stand is poorly placed as you indicate. Not sure why I let that fly.




That might not be a bad move. I mean with the SD here I would have all the parts needed to be swapped.

Hmmm.

I can deliver too, you're not that far away.

Here's a bunch of pics of the car:

Index of /mbforum/420selforsale

[JamesDean]

So I figured out what caused that hole in the middle of the car....

Apparently directly above that is the outer rear seat bolt.

I went to figure out why the driver's seat had such a mean lean on it and was rubbing the B pillar..

Looked down and saw my driveway!

My guess is water pooled there and rusted it pretty quickly from the cabin outwards.

I'm going to have to pull the front seats, carpeting and just cut out a big chunk of the floor and replace it with some nice sheet metal.