Rot on door sill?

[Argeo]

Well, a week cannot go by without finding new problems. Yesterday while peaking around I found rot on the driver's sidedoor sill. I punched my figure through. The hole is about 2 X 2 inches. It is located on the drivers side, underneigh where that plastic threshold piece starts on the end furthest from the door hinges. It is on the flat area and did not work it's way up or down where the horizontal turns to vertical. Also, when I look in the hole I discovered another hole in the wheel well. So if you take the back left tire off, you could poke your fingers through this hole at the bottom of the wheel up through the hole on the door sill (if you fingers were long enough). The metal that rusted out is probably 1/8" thick at the door sill, not sure about at the wheel well. I am wondering if you think this is structural where the car could snap in half or if not. Can I just bondo? Can I just weld a piece in place, or are we talking seroius work? I don't think the rot has touched the frame. Please let me know what you think?

Thanks.

[Formerly Steve Wilkinson]

I had a small amount of rot-through at the exact same place on the sill--'83 SC, and simply cut out a rectangle about 1.5 x 3 inches and welded a new piece in its place. Very simple. I didn't have any rust-through in the fender well, though. But in any case, I don't think you're looking at anything that will effect structural integrity if you stop it at this point, meaning proper drain holes, blocking or repairing the fender-well leakthrough and spraying the inside of your rocker boxes with some undercoating from Eastwood.

Stephan

[dtw]

At the points you describe, there are no structural risks. The sill spot you speak of is one of the most common rust areas. There is a depression where the lock post, rocker, and rear quarterpanel all tie together. The factory then leaded this depression to obtain a smooth surface. Acids in the lead frequently cause this area to rust out.

You would be ok just repairing the damaged sections. However, I would be highly concerned about ingress of water into the area between the inner/outer rocker. What usually happens is water gets in from holes as described on your car, or after the metal at the leading edge of the longitudinal finally gives out after the undercoating wears away in the wheel well (spray from the front tires is quick to eat through it). Then the rockers rust out from the inside out- often there is no visible sign until the damage is quite advanced.

Open a big enough hole when you do your repairs so that you can get a flashlight in there and reallly look around for damage.