My Doors Are Rusting Again ! Anyone got a good fix ?

[Derek A.]

The last time around I wire brushed the doors down to bare metal. Used a zinc based self etching primer, went over that with paint. I then put new rubber strips on the bottom with silicone to seal them off. I now have the rust back again. Looking for suggestions on how to repair this problem once and for all.

[TimGinCentralNJ]

...but last Fall, I went through this myself after reading this was a common problem with the E34. After pulling off the strips from all 4 doors, turned out only my driver's door had any rust, so I lightly sanded it and applied a few light coats of POR-15, followed by a thin top coat of Chassiscoat black (same company -- no affiliation). I haven't seen any rust, however, I also never reinstalled the rubber strips either. Seems they're good at trapping water in there.

Anyway, I've used POR-15 on old rusty floorboards of my old jeep, and a handful of other auto and non-auto applications, and I've yet to see any rust return. Just my $.02....YMMV.

Hope that helps,
Tim G.
'91 535iM

[jplacson]

I have some rust spots on the inside of my trunk, on the sides, behind the side carpetting... how do I get rid off these spots? Would it be recommended to weld a new piece of metal over this part to reinforce it after the rust has been sanded off?

[winfred]

move to the south or somewear without road salt, sell rusty bimmer and buy local non rusty e34, never think about automotive cancer again, live happly ever after

[632 Regal]

Silicone attracts moisture big time! Ever see people put it around windshields to stop them from leaking and the next year the whole window falls in? It's from the use of silicone. Use something else like urethane to fit the rubber back up there after you fix the rust. Also let the paint and primer "breathe" out for a couple weeks before you lock the vapors in with a sealant.

[winfred]

yep, it's fun when somebody silicones in their tail lights, after a couple years you just push em out the bolts are just for looks

[jplacson]

Does anyone have any experience with Ziebart Rust Treatment? I'd like to have my spots done, but I was told that their rust proofing screws up BMWs coating. Any comments on Ziebart Rust treatments (the one that turns rust into some harmless compound)? Thanks! :)

[Paul in NZ]

there are many product for this but i cant think of one.....check out your local hardware store, "anti rust" primers will include a reference to some prior treatment.Remember.....rust never sleeps

[632 Regal]

cant sand it prior or after treatment or it wont transform it. If it has rust pits to do it correctly you have to use an acid wash to get the rust out but make sure to wash all the acid out (baking soda) or you will paint the rust and caustic acid in there which is not good (ask my old 57 Dodge that I gave away to a good home)

[winfred]

the car disolved did it

[632 Regal]

the 80 hour prep and paint looked autorama for almost 60 days before pits started showing their ugly heads and a power washer peeled the seemingly awesome paint job into the driveway. Lesson learned: do not wash old car.

[jplacson]

I've heard of those products as well... but I'm not gonna claim I'm some great car mechanic or body shop worker... I know how these things are supposed to be used... but, uhm... I don't exactly wanna learn how on my bimmer. :P (ya, I'm too chicken to try)

That's why I was asking on Ziebart's "classic car" treatment, and if anyone here has ever tried it. They apply some rust converter as well, prior to painting. I guess if no one has tried them, I'll give them a try..it's a small spot anyway, in an unseen part of the car (behind the trunk carpet, sidewall) ... Inspection II didn't show any sign of it...and I wouldn't even have seen it, had I not tried to access the amp of my stereo, and check on the jack.

[Derek A.]

I know POR 15 comes with the acid treatment, which you are supposed to do before you brush the goods on. I have heard good stuff about that treatment, but once again the secret is in the prep.

I know BMW didn't use an adhesive in the original moldings, I do have some 3M black urethane windshield adhesive I can use in there after everything is done.

[George M]

I traded some e-mails with Sean in Europe who has been around many a rusted door. Sean has looked at a lot of E-32 and E-34 doors insides as well. He reports virtually no rust on the interior of the doors...a good thing...so concensus is these doors rust outside-in due to water/salt trapped by the bottom door moldings...and Sean has seen a lot of rust on inboard exterior bottoms as I have. I have had this condition on my E-32 and had it repaired as well. Bottom line is this...you can try all the rust inhibitors you want....but best result is pretty straight forward. Always remove cancered metal, refill it with weld, or filler and repaint...the best recipe for longevity.
George