Rust. E30 and 2002 enemy #1.

[apexede30]

Right after uninsured drivers. The purpose of this thread is for me to ask this question: how do we fight this valiant foe?
Let me elaborate. I'm sure it'll help atleast one other person.


If you think the underside of your carpet and floorboards are dry, please do yourself a favor and look twice. Just because the top of your carpet is dry, it does not mean the underside shares that state. Do yourself a favor and pull up a bit of the carpet from the floorboard, easily done by removing those black strip thingys on the bottom of the doors, or near the speaker area. Check for moisture. Where there is moisture, there is our enemy. And our enemy is quite annoying.

How do we fight floorboard rust? Other than cutting and welding, is there a good semi long term answer to the surface rust that will most likely be found on the floorboard? Do rust converters/preventatives work? The spray kind, or what not. On my 2002, it's mostly surface rust, but I can tell that it's not gonna end up good. And the moisture has to go as well, but I figure I can figure some smartass way to dry my carpet.

Anyone have any luck or success with fighting rust in these areas? All constructive comments will be greatly appreciated. Flames will be considered and thought upon profoundly.

PS: Yes I searched, and I even searched the net, but it seems most websites end up telling you to use their product or your car will forever be lost to oxidation.

[Justin B]

Ive used petroleum jelly before, as well as picklex 20, both work well. The interior of my 2002 also has a generous coat over everything on the floor/seat back area of ZeroRust, basically like Por15 but a lot cheaper.

[apexede30]

Ive used petroleum jelly before, as well as picklex 20, both work well. The interior of my 2002 also has a generous coat over everything on the floor/seat back area of ZeroRust, basically like Por15 but a lot cheaper.

So...With these products, which I am unfamiliar with, you just clean the surface and spray? Or is some kind of heat gun required, I dunno...Bear with me here lol. I'll go to advance auto or autozone and check this stuff out if you say that they stop rust decently.

[Pinepig]

The only way to stop rust is to seal the metal from the water. Any good barrier coating applied per the directions will work, the stouter the coating the longer it will last.

Or move to California.

[apexede30]

Hmm. So it won't be too bad if I shave a bit off the top with some sandpaper to make sure I get a bit of rust off, gun it dry, then cover it with one of these rust preventatives? Or..should something else be done alongside this treatment.

[z31maniac]

Knock down rust with wire brush, spary with phosphoric acid to neutralize, then wipe off with a clean cloth, then seal with something Por 15 or similar.

Or cut it out, weld in patches and seal it. That's the route I took, but I'm building my car for the long term.

Depends on your goals.

[alpinaclone]

Make sure all rust is removed or even the best coatings won't be more than a false sense of security. Even rust neutralizers won't get all of the way through thick rust. On the floor of the old alpinaclone I cut out the rust in the worst areas and replaced the metal, in the areas that weren't perforated I just wire brushed and applied rust neutralizer. After 7 years, when dismantling the car, upon removal of the carpet, the brushed areas had rotted through. The floor by the way, was coated in undercoating underneath the carpet. For the most part it worked well, I think if I hadn't fucked up as stated above it would have kept the rust at bay.

[morningsmiler]

We use Wurth rust treatment for surface rust, but it works well on even deeper stuff. Of course it doesn't fix structural deficiencies, you have to weld in new metal for that.

Takes a topcoat well, too.

http://http://www.pelicanparts.com/c...UGARG_pg11.htm

[BeirBrennerE30]

step one... get rid of ALL rust ( grind away surface rust and replace all panels that cant be saved. Seriously everything must go if you plan on completely stopping rust)

step two... Clean everything well, etch and seal with a good primer(no powdercoat)

Step three... paint pretty surfaces with a quility paint and use a por15 product o the not so pretty(undercar)

step four... keep her waxed with a good coat of wax on the paint and touch up any scratches in the non painted area PDQ!

step five... stop driving your car in bad weather, snow and rain. My car has never seen a winter never spent a night outside and has only been in about 25 rain storms since it was new and I have had no rust at all.

[OrganicMechanic]

I have discovered that the M3 I picked up is rifled with floorboard rust. I mean serious rot. I have decided that cutting and welding that is the only way to replace the missing floor sections. I use siilca gel packets to dry the inside of the car seeing how the heat will raise the humidity inside the car and the packets will absorb the moisture. I have some half pound packets that came in our new Haas Milling center. I have also found that by keeping the packets under the seats it helps with keeping the mildew smell away as well. so when ever you buy something that has silica gel packets just throw them under your seat and remember to replace them when you vaccum.

[z31maniac]

step five... stop driving your car in bad weather, snow and rain. My car has never seen a winter never spent a night outside and has only been in about 25 rain storms since it was new and I have had no rust at all.

But driving in the rain is fun!

[GraphicRage]

When I swapped my interior, I found some surface rust, so I por 15d the whole thing. Unfortunately the leaky AC drain hose for years did too much damage to the passenger floor pan so although it's thick with por15 for now, I do plan to cut and weld a new piece eventually.

[JAM]

blast

cut

weld

por 15 (although the shit is like $130/gallon)

[tim88325is]

My e30 had rust really pretty bad. I have a tig welder but doing thin sheetmetal on the car is tough and time consuming for me.

What I did was...

Cut out all the rusted metal.

Fabricate new patches with 20 gauge.

Install and fit patches with #6 self-tappng screws.

Remove screws and use 3M structural panel adhesive to bond metal patches, reinstall screws. 2 part epoxy adhesive sold at auto paint/body shop stores.

Remove screws in most cases or ground them down, filled holes with adhesive.

For external areas, I ground the patches and adhesive relatively smooth and filled with USC All-Metal filler as a base filler. More resistant to moisture than regular bondo stuff.

Paint internal areas with ZeroRust paint and topcoat with rustoleum black to blend. Zerorust is way cheaper than POR and safer to work with.


I expect to hear strong opinions on the method but I did this because of my welding skills, the e30 isn't a show car, the fact that the adhesive will not rust or let any moisture, and it is a fast process.

I used a lot of sheetmetal, I think like four square feet!! Both sides of the trunk, underneath both taillights, both floor pans, driver's side inner wheel well and underneath fusebox.

Make sure all your seals are good, taillights and windows and trunk. I am convinced most rust happens from the inside out because the water can sit for extended periods of time trapped under carpet. Water splashed onto the underside of the car obviously runs or drops off fairly quickly.

[318isbmw]

Be careful w/ por15. Its definitely the best with the rust stuff, but it has chemicals in it that regular respirators don't cover. Had a friend get it into his system through using a regular respirator setup and got really sick(like was so hot just layed on the ground naked and still sweated like hell for a few hours then after that couldn't put enough clothes on to keep himself warm) from the chemicals in por15.