Firewall Rust

Twenty Mike Mike

Twenty Mike Mike

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Any opinions on the level of difficulty, or even the advisability, of repairing the firewall rust?

I don't think Rust Reformer is going to help...

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1972 BMW 3.0CS 4-Speed

Bid for the chance to own a 1972 BMW 3.0CS 4-Speed at auction with Bring a Trailer, the home of the best vintage and classic cars online. Lot #170,973.
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It's bad.

The hole is so big that it is not something that can be fixed with just a patch. The hole behind the glovebox actually gives access to the cavity in the front fender. I've never seen a hole there that big. (Pic with green circle)
The rust also came out on the other end, as you can see in the pic with the red circle. There, the visible rust was fixed. I doubt if the layer below, which must be worse, was fixed as well.

In order to fix it all properly, the fenders need to come off. When you're doing that, it means a respray.
When you're respraying ( around 10-20k usd seems to be a normal going rate), doing the whole body isn't uncommon.

In this case ( but also with the majority of other 'unfixed' e9's ), the rust is everywhere. Expect to need new floors, doorskins, rear valance, rear quarter panel lower patches, front fender lower A-pillar patches, new sills etc. The whole lot. That's 10k in sheet metal alone.
The front fenders look like they have rust issues, though fixable with skillfully welded patches; no need for full NOS fenders.
Outsourcing just the body work would be 50k at least in the US.

The BAT offer basically is a whole resto project where the value lies in the parts, not the body.
 

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I’d second all of that.

I’d say it’s the hardest part of the whole shell to repair as there is so much dismantling needed just to enable access, so unless you have really deep pockets and are willing to spend more than it will ever be worth, I’d pass.
 
CSteve said:
Look in the glove box. There you will find the registration, an insurance card, and a signed Organ Donor Card.
Click to expand...
LOL!

Thanks, guys. I've had two coupes, neither of which had rust issues like that.

Why, oh why, did I sell that second one?
 
How does rust get in that place? Is this common? Do all E9s have this weakness? I don't think so. I would be curious what event brought about conditions for rust to run wild at this very spot. Hmmm. I think I read it was bought from the New Jersey area, where it had been in storage. Wonder what precipitated this extreme corrosion. Reading what is necessary to effect a proper repair should frighten any casual buyer away. Perhaps an enthusiast with welding skills, space, time, passion for E9s, and spare $$$ could save this. Hope so.
 
@bluecoupe30! ,

The rust in that area starts as water enters the triangle shaped cavity.

It usually comes from above, when the foam layer between the top of the outside fender and the inner fender crumbles (which just lasted ~5years or so). Then spray from the wheel is thrown up into the fender top, and it drips down into that corner.

Here's a picture of the glovebox area, as seen when disassembled to fix the rust there on another car. The slanted plane pointing downwards towards the front is what you see when you open the glovebox. Also the car in the pic below has a hole there; it's typical. It's a bad place to have rust as the part running forward&up from the bottom of the triangle shaped box is the strut mounting point; you want that to remain solid.

Pic origin, with lots more pictures:
 

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eriknetherlands said:
@bluecoupe30! ,

The rust in that area starts as water enters the triangle shaped cavity.

It usually comes from above, when the foam layer between the top of the outside fender and the inner fender crumbles (which just lasted ~5years or so). Then spray from the wheel is thrown up into the fender top, and it drips down into that corner.

Here's a picture of the glovebox area, as seen when disassembled to fix the rust there on another car. The slanted plane pointing downwards towards the front is what you see when you open the glovebox. Also the car in the pic below has a hole there; it's typical. It's a bad place to have rust as the part running forward&up from the bottom of the triangle shaped box is the strut mounting point.

Pic origin, with lots more pictures:
Click to expand...
Thanks Erik. Very helpful!
 
Keep in mind that what you see is likely not all that is eaten away.
And- not many shops want that work.

think $ 70k to fix that car and 2-3 years.

Or just buy a nice one for $ 80k and drive it home tomorrow.

your choice…..
 
Right Don! Buy now at $80k. That $70k over 2-3 years fixing will inflate to $90k. There will be more undiscovered rust and parts and labor increases and... Well, we all know that drill,
 
Like all have said before, these cars rust from the inside out. I learned the hard way, and will only buy a coupe that is orginal rust free or has been expertly restored. This car shows all the classic signs of needing a full rotisserie. Unless you have deep pockets and enjoy lots of pain and torture in your life, run to the nearest exit ramp and have a beer or two. It will cost you a ton less and be more fun!
 
ya, one of the big reasons I sold my CSi was that it had firewall rust.

THank goodness my 2800CS is fairly (haven't taken the paint off yet) rust free.
 
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