Underbody Rust

[apechimp]

I just noticed this when I was flushing my brake fluid:




How worrisome is this?

From googling it seems like I should use a wire brush and sand paper to grind down the rust and then put rubberized undercoat on it. Is that the way to go about this?

[l4zy415]

Usually a shop would cut that out, then weld in a new piece of metal, then they would add bondo and either paint it or add that rubberized stuff.

[90Legend L]

If you plan on keeping this car on the road for a while (years), then this is very worrisome. Looks like you've got frame rot going on there and it will only get worse if you don't get it fixed.

Yes, fixing it will require scraping, grinding and sanding all the rust away, then either welding in new metal or using fiberglass to repair it, then paint and undercoat. Prepare to see a lot more rust once you start digging through the paint and undercoating, as the rust you can see is probably just the tip of the iceberg.

Sometimes this rust starts from the outside (rock impact causes exposure of metal, then it starts rusting) but sometimes it comes from the inside, due to water leak and pooling. Make sure you find and address any water leak that could have caused this from the inside, or the rust will come back.

G'luck.

[Dreams94coupe]

back when my friend had a g1 sedan his car was so rusted that the back seat fell in. Then one day while he was driving (5spd) his foot went through the floor. Now you would think after that he would give up but he was determined the repair which he did. The back ended up being when his motor fell out due to frame being rotted out. So i suggest you proceed cautiously.

[apechimp]

How would I know whether or not the hole has been caused by a water leak?

[LegendLand]

Originally Posted by Dreams94coupe

back when my friend had a g1 sedan his car was so rusted that the back seat fell in. Then one day while he was driving (5spd) his foot went through the floor. Now you would think after that he would give up but he was determined the repair which he did. The back ended up being when his motor fell out due to frame being rotted out. So i suggest you proceed cautiously.

Wow I didn't know things like that happened in real life haha.


To the OP. Like the others said, it is best to repair that soon if you plan on keeping the car long. If not, it will get worse and worse. I recommend taking care of it.

[90Legend L]

Originally Posted by apechimp

How would I know whether or not the hole has been caused by a water leak?

As you start digging into the rusted area, you can usually tell where the rust started. If there is rust on the outer surface, but good solid metal behind that rust, then it started from the outside. If you see areas where there appears to be solid metal on the outside, but the inside is all rotted away (held together by the paint on the outside) then it came from the inside and there is water pooling in there and rotting it.

[apechimp]

I have no idea how to weld and doubt this is the project to to learn how. Does it make any sense to grind the rust out and take it somewhere to get the welding done or should I just let the professionals handle this one?

[Artillery129]

let the pros handle it, could get real bad real fast

[canucks]

rust repair can add up. rust is like cancer and it probably will come back again even after being cut and welded