Rust below rear WS : What to expect?

[Austin85]

Saw the post on rust below & I have to deal with similar on my 300DT ('85); My rust is on the body itself, just below the rear windsheild.
I have no leaks into body and no rust below; But anyone have experience with this repair?
I know I have to remove the rear WS to get at it....I have a new seal waiting...But what is the best way to fill in the rusted out body along corners of rear WS??? There is maybe an 1/8th of an inch of rusted out body below the WS frame...
Never did this before...I read that bondo is NOT the way to go....( I have RustDoctor to inhibit the rust growth..)
And what about paint touch up to cover repair????
Thanks anyone!!!

[pawoSD]

Ours didn't look too bad from the outside either and also did not leak, the real damage was discovered after removal of the window....

[Austin85]

I can't wait...
Any idea how to repair the actual body of the car vs the frame that you had to do???
You won't have to paint from the looks of it...I will...

[t walgamuth]

the real way to repair is cut out all rust and weld in new. but that is not cost effective in a car that is worth what ours are worth, and it is still very difficult to keep the rust from reoccurring.

i would grind and cut away all rusty areas, then if necessary i would use pop rivits to put in a patch or if it was small i would glue them in with epoxy or the type of bondo that has aluminum or fiberglass in it. it is a trick to keep it compact to not cause interference with the gasket. the good thing is that most of it will be under the gasket when done so it doesnt have to be perfect. when the patch is solidly in place and sanded as smooth as necessary you need to prime and paint with a high quality paint. i always buy a pint at the auto paint store that is matched to my cars paint of high quality sherwin williams (i believe that is the brand). i would apply it with a small brush. and very important i would get behind if possible and prime, paint and undercoat from below.

if done this way it should last for many years. the key is to get all the rusty areas out. if you dont get them out, like cancer they will rejuvinate and grow. the rust binder works only on surface rust that has good solid metal under it.

[Brian Carlton]

Rust is a strange beast.

I have experience with a small rust spot directly below the solid glass window near the back of the van. A patch of surface rust developed right underneath the window, on the body. Not too big and not very deep. So, I pulled the window out and took the gasket out. Then ground the rust down to bare metal.

However, the metal was not perfectly smooth. The rust left some erosion in the steel. But, it was completely clean and bright when I was finished.

Used a touch of Bondo to just fill the depressions and primed and painted it.

Reinstalled the glass.

Two years later, the same spot develops the beginnings of rust all over again.

So, I repeat the entire process, again, and treat the area with a rustproofing agent priot to Bondo and paint.

We'll see how long it lasts.

I have a suspicion that it's quite difficult to stop rust from continuing onward once it has taken a hold inside the steel.

[t walgamuth]

if you used ordinary bondo that may have been the problem. i have heard that it "attracts" water. the fiberglass or aluminum bearing bondo will not (supposidly). now you also have to be careful about putting bondo on metal that is not bare. it will, i think, eventually release. anyway hopefully it will last longer than last time. a compromise might be to do the rust binder then sand it so that your filler will bond to the bare metal areas and the pits will be bound with the rust binder. rust is a devil!

tom w

[Brian Carlton]

Originally Posted by t walgamuth

if you used ordinary bondo that may have been the problem. i have heard that it "attracts" water. the fiberglass or aluminum bearing bondo will not (supposidly). now you also have to be careful about putting bondo on metal that is not bare. it will, i think, eventually release. anyway hopefully it will last longer than last time. a compromise might be to do the rust binder then sand it so that your filler will bond to the bare metal areas and the pits will be bound with the rust binder. rust is a devil!

I think you are right about that. Every time that I use Bondo on the van, it's worth about two years and the rust eventually returns. It definitely returns from inside. The rust is still there and air can get to it from the back. So, even though the Bondo and paint prevent any water intrusion on the outside, the rust just continues on its merry way from the inside.

With regard to the surface rust, I still can't figure how the water penetrates the paint and gets into the Bondo.

Whatever I'm doing, it's not a permanent repair. Fortunately, the van can be considered a "practice" vehicle.

I "practiced" changing plugs on the van yesterday. Started it up today and it seemed rough. A short drive resulted in some backfires and significantly reduced power.

That's what switching 6 and 8 will do to you.

[Austin85]

for returning rust check this site; www.therustdoctor.com