Colleagues,

Working away at the corrosion from the battery box down to the front right jackpoint. I removed the fender and the pictures are attached below.

A couple of comments and questions.

1. The material behind the front wheel well seems to be a mix of sheet metal, foam, and some kind of rubbery backing. The rust has pierced through all the way to the backing in some points. What do you suggest I use to seal this up?

2. Just below and outside the battery box there are two flexible, sheathed conduits running through the firewall. Both have spots in the outer insulation that have 'eaten through' (presumably, due to battery corrosion).

One looks like vacuum lines, but the lines still look sound so I'm going to cover up the sheathing and put it back.

The other has a bunch of little wires (thin stuff, 22-gauge or so) running up to the lights? Horn? Sensors? I can't really tell. The picture below shows me holding up the bundle. The little blue one has been completely eaten through. The others look OK at the moment.

So presumably, something somewhere isn't working. But for the life of me I can't figure out what it is. Does anyone know what the wires in this bundle do? And specifically, what the blue one does?

Matt

Attached Thumbnails

     

Yikes

Cut out the bad metal and make yourself some patches. After making the patches either mig weld or rivet them in. Seal the area with POR 15 . I would use stainless steel sheetmetal since you wont have to worry about it rusting out if you seal the areas around it properly.

for the wires that have been corrided through by battey acid cut them and reconnect them using connectors. the bubbery stuff is the material used to stick the sound proofing to the firewall. If you Plan on welding patch pieces in place I WOULD remove the dash, held in by four screws and scrap it off. The heat generated by the welding WILL ignite the tar.

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

Yep, I respliced and reconnected the wire and sealed up the flexible conduit. Still have no idea what that wire was connected to.

Below are some 'updated' pictures of both wheelwhells after a little more cutting, picking with a screwdriver, cleaning and a bit of wirewheeling. Yes, that is clear air on the driver's side - about a 10 inch by 2 inch gap after I cut away some of the sheetmetal. You were right, the rubbery stuff and the foam is the soundproofing behind the footwells. I'm actually suprised at how thin the sheetmetal is up here.

I'm going to try something tomorrow that doesn't involve welding. I'm almost afraid to throw it out in the forum at the moment, since I have a feeling I'll subject myself to hoots of derision. But I'm going to try it anyway.

Attached Thumbnails

   

You can rivet patch pieces in since it wont be visible to the human eye. I would recommend riveting it in due to the fact that you can ignite your car on fire and you run the chance of distorting the metal.

I would remove the dash to the repairs properly. Removing the dash involves removing 2 10mm and 2 8mm bolts. Also involves removing the ring around the dash and removing the 2 interior pieces adjacent to the dash by carefully prying up on them with a screwdriver. Also you must remove the speakers as well

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

I just went out to take another look at it, and it seems like there is plenty of room to patch things in without removing the dash. Unless I'm missing something. Granted, it's getting a little dark outside and I didn't really probe from the inside of the engine bay.

I hope I don't have to pull the dash. Is there something in particular you are thinking of, that requires this?

Matt

I am doing a restortation on a friends 300D and the battery area is pretty much like yours but worse and the rust has spread behind the support brace to where the sway bar attaches. To properly take care of all the rust and fix it removing the dash is necessary.

This car has climate control problems as well which are being addressed so the dash is off.

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

One thing you could try is layering fiberglass cloth and fiberglass to build up the areas. I did that very successfully on my SLC, and I've seen this technique last years in Great Lakes weather on quite a few cars.

Secrets to making it work.

1) No Bondo: too water soluable
2) multilple thin layers of fiberglass. The fiberglass polymerizes better and the layers build strength.
3) Apply the patch to both sides, inside and out, if possible.
4) Drill strategic holes to allow both sides of the fiberglass to combine. This chemically rivets the patch so it will stay in place.
5) I have occasionally used multiple fiberglass cloths when extra strength is needed. Usually one on each side of the patch will suffice.
6) any filler needs to be reactive and water impermeable.
7) use some undercoating to blend it the patch with the surrounding metal.

There is one serious problem with using rivets on a job like this. They collect moisture and can rot. You need some type of hermetic seal to keep the rust from spreading. That is the biggest problem with metal repairs using any type of rivets. Fiberglass done right provides strength and the hermetic seal that will resist further damage.

Now if you are repairing the car for shows, they tend not to like that type of repair.

Unfortuately I cannot recommend any products. I've seen some repair products recommended on the forum. I would ask anyone who recommended those products. I'll try to take the time to look up the chemistry and see if I can understand them better. I haven't done this in years. I learned this technique from a ship designer's son. It really can work quite effectively.

Heres a few pictures of mine..I have welded the rear floor, front floor and wheel well....now time to attack the cause!!!!

Attached Thumbnails

   

Here's the repair on a hood hinge leak/battery leak....I really wish I had taken a final picture (with the last patch in place), however I was in a rush. Notice I used liberal amounts of seam sealer. This was used on both sides of the repair. The silver paint is Rust Bullet.....which is very $$$$ and a pain to work with...Thinking of trying zero Rust next...
All welds were layered tack welds to minimize heat and potential fires....This method works well if you up the wire speed a little....

Hope someone finds this of use....just waiting for rain now....

Attached Thumbnails