If it is stone chips that have rusted then temporary measures can work. I did that on my e39 bonnet and bought a few years before a full respray recently. I ground out the rust with a dremel and painted.

That is because the stonechip rust is from "outside in".

Some of your rust looks to be "inside-out". If you grind it out you will find it very much worse than it appears - like a proverbial iceberg. It will probably need metal cutting out and new metal to be welded in.

See what others say but I would say get whatever access you need by removing things like wheel arch liners etc. and buy time by spraying dinatrol, bilthamber or waxoyl in behind.

 

I will comment on this since I’ve done an extensive job on my E46 regarding rust and replacing sheet metal parts.
It can be done for sure. But if you are just going to sand all the rusty areas down only to paint them as a temporary fix I would suggest to just treat it with quality rust inhibitor and possibly a primer. Any top coat on that is a waste of money and time since you won’t be welding a fresh metal in those areas for now and the rust can get back very quickly. Yes, it’s going to look bad for a while, until you sort it out properly and have it painted in a body shop.
One interesting thing to note is the cause of those rusty areas.
the rocker panel rust on the front near front wheels is a rust that forms as a result of a stone chipping the paint. There is approximately a 5-6cm long cavity before the inner portion is sealed off with sheet metal. It’s prone to rust there also because road dirt and debris gets caught there and accumulates moisture easily. You will see it when you remove wheel and inner plastic fender. This area is circled in white color.
Then there is area that I circled with red color. This can be also found further back multiple times. This rust forms due to 4 holes in rocker panel and mainly due to stupid design that BMW came with. It’s the plastic side skirts that hold there using plastic male and female clips. Those clips hold in the rocker panel using green plastic inserts that just damage the paint around them due to vibrations and movement and the rust starts to form. It’s weird because the rust tends to move upwards and the result is what you see on your car. Mine was the same and dozens of rusty E46s that I came into were also the same. You can cut all those parts out and fabricate patch panels out of sheet metal and weld it back but it’s not ideal since you can’t treat inside of those welds and the rust can get back after a few years due to inside cavities condensation. Therefore it’s better to replace the whole rocker panels. You have to talk to the guy who will do this. Not a lot of people do this since it’s expensive (if done properly which is important). The patience and preparation time and quality of used primer and seam sealers that you put into this will reflect the lifespan of such repair. Then there is the rear wheel arch. Another commom place for E46 to rust there. It can be stone chip but most of the times it’s moisture that gets inside (there is a huge cavity under the outer sheet metal). The water gets there easily because wheels splash it inside due to seam sealer that seals iner fender to the outer arch having cracks in it. It tends to separate and allows water to go inside and it can rust badly. It’s circled in yellow.
So just to point out important things. If you want to keep the car it’s totaly worth it. Find someone reputable. Reputable might mean expensive but it is what it is.

 

Welcome to the rusty E46 club!

How long are you planning on keeping the car, and what is your end goal? Cosmetically the rust doesn't look that bad, but keep in mind that it's coming from behind the panels, so there is a much larger area that needs to be fixed than what you can readily see.

If you intend to keep it for less than 5 years and it's going to be a daily driver I probably wouldn't attempt to repair it. Just manage the rust instead with Fluid Film, Permatex rust converter, or some other rust prevention. I've got a rusty E46 sedan for my winter car and I've just accepted it for what it is. If you pay to have a shop fix the rust you'll get little to no return on your money invested when you go to resell the car in a few years, and you'll take a big loss overall.

If you plan to keep the car for a long time, want it to be a pristine weekend car, not drive it in the salt, etc. then you could have it fixed the right way by cutting out all the rot and welding in good metal. You'll probably exceed the value of the car in repairs by the time you're done but you can (sort of) justify that by spreading that cost out over many years of ownership.

If the rust really bothers you that much, a third option would be to just sell the car and find a different one that doesn't have rust to begin with. You just bought this one, so you don't have the burden of having dumped a bunch of money into it on maintenance and mechanical repairs. You could still get out of it for minimal loss, or even flip for a profit. It usually ends up being cheaper in the long run to spend more up front on a rust free car vs buying something for cheap but needs a lot of work.

I'd keep it though, and just enjoy the hell out of it. Who cares if it's a little rusty. Keep an eye on the jacking points and keep those treated to prevent further spread of rust, and just drive it.

 

The problem is what your not seeing. You'll need to completely cut those sections out and replace the sheet metal. It's rusting from the inside out not the outside in.

I've had to deal with this a couple of times on some cars that had rust issues. One of them just ended up being a parts car because once I started cutting sheet metal it just got worse.

Cheers,

Poon

 

What an outstanding response to come back from work to! Really appreciate the detailed responses and suggestions.
I live in Ontario and honestly after close to 3 months of following kijiji and marketplace ads, this 330i was one of the cleanest - rust has destroyed many cars up here. The previous owner invested quite a bit in preparing this vehicle mechanically for his son but they decided to get him a manual trans (recent work included for interest).

I paid $7500 CAD (~$5500 USD) and just paid another $300 to BMW for a second key. Looking over BaT, Kijiji etc, autotrader (including in USA) this car has a lot going for it for that price. 330i engine, favorite color, immaculate interior, maintenance history - I think I found a keeper. However - this is not meant to be a show car and when the kids are older and out of car seats I'll go find my dream car with 2 doors and a manual trans.

Ultimately it's my solution to having a daily driver that i'm excited about everyday but is reasonable price - my wife drives our 'primary' car with kids everyday now. The rust really doesn't bother me visually but I would like to keep this car for a long time (though based on past behaviour that may change).

The solutions here I think will help me feel like I'm doing something more than just watching it get worse. I spoke to a reputable shop who quoted in the $2-3k range but hasn't seen the car in person yet. In the spring I'll probably get it looked at in detail. Jack points are clear of rust

Until then I really appreciate the advice here and I'll go get some fluid film and see what I can do! Looking forward to many years on this forum - thanks for warm welcome!

 

That stuff on the sill/rockers is gonna be nasty. Mine (2002 sedan) looked a little worse than that when I bought it. I was appalled at what I saw when I pulled the plastic trim off. I bought it to drive hard, not be be pretty, so I just took a grinder with paint removal attachment or flap disk to anything bubbling and hit it with rust converter then black primer for now. I don't care what it looks like, just don't want the chassis rusting away.

There are a series of plastic clips all down the side holding the sideskirt or whatever on. They are attached through holes in the rocker. Almost all of those holes on mine were pretty rotted, to the point where there is no welding in patch panels, whole rockers need replaced. I cut away probably about a foot of the rear part of the rocker panel because it was just falling apart. Sprayed all exposed rusty stuff that was still solid with rust converter. Rear jack points are pretty ugly, won't be using them until I can address them. It's being driven without the trim on one side and a gaping hole in the rocker.

I also have a rear floorboard rust spot that will likely need cutting and patching. Also, the trim pieces inside the bottom of the doorframe, that attached to what is part of the rocker panel, had bubbling rust around their holes.

When I took the paint removal attachment to one of the quarterpanels, bondo dust flew everywhere 😄

I hoped to work on the rockers this winter, but the list of maintenance items got too long. In your shoes, I would just accept that it's a rust bucket and not gonna be pretty.

 

I would definitely take off the pastic covers around the sills. In my case I also need to do some repair there. You might even want to check your jacking points. If they are pushed to far in, there is some work to do

 

 

Thanks for sharing this vid.
A little scary to see how E46 loves rust.
I hope my E46 325TI will last for 10 years, when I am done with overhauling.
Then I am okay to say goodbye.

 

Good video! Something that seems to be frequently overlooked until it becomes severe.

 

I live by the coast rust is my number one enemy,and i am very prepared.

 

The track car we picked up earlier this year had some rust on the rocker panels. We were able to source some clean, rust-free body panel sections that we had cut off a car at a junk yard, amazingly in the same paint color (which actually doesn't matter to us since the car has a wrap). My husband spent some time last weekend cutting off the entire section of the passenger side rocker panel that had rust, and one of his guys will be welding on the new clean rust-free body panel soon. We'll do the same for the other side. We've been going over the rest of the car with a fine-toothed comb to ensure there are no other rust spots (while we install parts, remove stuff for weight savings, etc). It seems like a big pita, but we want to make sure there is no rust being overlooked or left behind.