The rear passenger door bottom is starting to rust. It started last winter, now it's spreading to the full length of the door. What should I do? I was thinking of grinding the rust away then put s coat of primer and then finally hand brush it with gray rust proof paint. No one could really see or notice that area anyway. I don't have the funds right now to get it done at a body shop. What do you think? Does anyone else have this problem?
BTW I have a 2002 Cavalier.

2002 Cavalier

its a common problem. is it just surface rust or is it through the metal? if its surface rust you can just grind it down til its gone then repaint the area.

Grind it all out the best you can, brush on POR-15, then paint over that with your gray paint as if it were bare metal...

If you don't catch it now, you'll regret it. No body shop will do it right, I've tried and paid 600 bucks for it to just keep re-occuring. I have the same issue with both my cars, but my sedan is the worst. I'm currently stripping the whole under carraige and por-15'ing the hell out of the whole bottom, then sealing it even more with under carraige spray.

... its a nightmare but I'd like my car to see another ten on top of the 9 its already seen.

It is just surface rust, I'll grind it down to bare metal. I don't trust body shops, they just want tp make a prifit and most don't care about their work or customer satisfaction.


2002 Cavalier

What should I use to grind and remove the surface rust?


2002 Cavalier

What should I grind the rust off with? Will a round course sandpaper disk on a drill work ?


2002 Cavalier

to do mine i used, by 3M a whut looked like a steel wool brillo pad type deal that was round/disk shaped. it was called like a rust/paint remover. if u go to an advanced auto parts, look bly the fiberglass/bondo and sand paper and u will see it. it attches to a drill and costs about 10 buck. it worked wonderfull on my trunk rust. im about to get my doors quite soon. i would reacamend. geting a gel/liquid rust NUETRALIZER. it turns whutever rust u leave black and "kills" it. use that after u get down to bare metal. then make sure u rinse it off real good. then. and this is a must if u r going down to bare metal. get SELF-ETCHING PRIMER. i believe it only comes in a light grre/gray-ish tint. but it is ment for bare metal applications. then just paint over that and yur good to go!

Before you go digging in take a gander at the how tos on this forum. Yea it has a lot of restorers and pros on there but they are very helpful. I for one use a 4" Harbor freight Chinese grinder for most rust removal using a stainless steel brush. Actually I have a few of them as they are dirt cheap and work well and its easier and faster to have a cup wheel on one and a round wheel on another. Any of these clean the rust off faster than a sander though you will never get it as clean as a sandbaster. The pro's on the website said there is no way to fix that rust inside the door frame bottom so it won't come back and to that extent they are probably right but you can stop it and hold it back for many years by just knocking it off and priming and painting it well. For that inside out of sight stuff I simply use a brush. That way you put it on nice and thick and you won't need to worry about messing with a spray gun. Pay special attention to the area where the outer door panel folds over the inside door piece along the bottom. There is a strip of mastic or door sealant under the paint and there will be rust under there if there is any around. I dig that all up along the bottom edge with a 1" wire brush on a dremel tool. Dremels are handy in all sorts of spots like that.. Since you will never get all of it completely put on some PHOSPHORIC ACID ETCH and let it dry before priming and painting. Thats the stuff they make Naval Jelly out of and it neutralizes the tiny pieces of live rust in the bottom of the pits. Then you can prime and paint. Don't skip that acid etch as you need all the help you can get down there. Parks makes it for non automotive applications and its about 1/4 the price as auto stuff and the same thing. I just spray it on using an old windex bottle. I prime and paint mine then when its dry put a bead of body panel sealer on the crack then paint over that in a few days to seal it even more. That should bury the rust for a few years at least.
You can save a lot of headache by cleaning out that area when you wash the car too. Spash that area down and spray water up one of the weep holes in the bottom of the door so it flows out the other. Keeping those open and clean removes the sand that sits inside the door holding moisture down there rusting things.

NAVAL JELLY! thats whut its called...i forgot, lol. i was tryin to describe it there, lol. but u use a sprat bottle? i used a paint brush. so that u get it on there good, and like almost rub or "massage" it into the rust to nutralize deep down into it to HOPEFULLY stop it completely! but good info and EXTREMELY close to whut i did! i hope it turns out good for u Avid! good luck!

Thanks for all your suggestions. I attached a wire brush to a drill and tried to remove as much rust as I could. The rust is only at the bottom of two doors, not extending beyond the drain holes. There was still some rust, I couldn't get all of it off. I then brushed on some rust neutralizing gel which I purchased at Canadian Tire. I then rinsed it off with water and dried the area. I looked around my garage and found 2 bottles of primer, both wouldn't spray. The stores were closed by this time so I sprayed some rocker panel stuff into an empty margarine container and brushed it on thickly. By the time I finished putting this onto the 2 doors, it was dry already. I hope this delays the rusting process for at least a year. Do you think I got enough of the rust off? It was bumpy and the wire brush could not remove it all.


2002 Cavalier