E36 rusty arches! Are these bad or not?

[Daniel.w.leigh]

So, I have recently bought a 66,000 mile 1998 E36 328i convertible, probably for too much money but low mileage and tidy ones seem to be expensive now.

The car is in pretty great condition, power roof works (and is actually watertight), bodywork is great, history is great, it’s clearly been very well looked after.

The only downside to the whole car, is there are a couple of areas of rust coming in around the rear arches, one is a bit worse than the other. They’re not showing through on the actual body panels yet, but I just wanted some advice if I may on;

a) is this likely to get much worse on a car that’s a 3rd car and will only be driven in good weather?
b) how long is this likely to take to get ugly and show on the actual body?
c) what sort of cost would I be looking at to repair this?


any advice would be appreciated, there aren’t many nice E36’s left so I’m keen for this one to stay nice!

[swisstoni]

Sorry to be negative but there’s more rust here than is visible.
It will get worse.
It needs taking back to bare metal and either neutralised or cut out.

[ingenieur]

Now that the paint has lifted and the rust has started there's no use taking any corrective action as water will be able to get behind the paint and into the flaky metal and continue the corrosion.

However...

If it is not visible on the outside parts of the bodywork you can leave it until it starts to show. If that's what you want to do. It might never get to the face of the panel as it is a natural process and there's nothing written in law that a little bit of rust on an edge must bloom into a big blemish that's visible on the outside.

[SimonTheSailor]

Have a good old scrape around , treat it , prime it, brush paint back on. It's on a place nobody will notice so you can hardly make a mess of it.
It looks minor to me so you could keep it a bay for a while.

[g3org3y]

Is this car a keeper? If so, I'd try and get it sorted and sorted properly.

Be wary that the plastic sill covers can also hide a multitude of sins.

See you in the BMW section: https://www.pistonheads.com/gassing/forum.asp?h=0&...

[996TT02]

The bubbling is much worse as bubbling than completely removed, let that sink in first before you imagine that you should just not touch it for fear of making things worse. As another poster pointed out, that will retain moisture. For starters at practically no cost remove everything that is removable, use a degree of force / tools, remove till there is nothing to be removed, just pitted metal. Only then can you assess properly. You might want to live with the result for the short or even the longer term - after removing all scabby rust, treat with a rust killer. After cured, rinsed if applicable, dried extremely well (hairdryer or heat gun with care) use any metal paint, I would use black hammerite. Let that dry extremely well, many days. Afterwards, apply underbody sealer of the sort that dries to an overpaintable finish. Not necessarily to paint it but so it goes hard as that is an impact zone, the greasy sort of underseal won't cut it. If there are crevices - that place you might have the inner and outer wing welded together depending whether front or rear, you should use a cavity wax product, this will penetrate, use it before the underbody sealer, which is applied after wiping off all excess cavity wax where the sealer is going to go. Looked after periodically, with the occasional squirt of cavity wax after a wash, the rust may be kept at bay for many long years.

[ingenieur]

Just a note to say I wouldn't try to remove it unless you are having it done properly. I definitely wouldn't use Hammerite as the formulation isn't compatible with a lot of other paints and will cause reactions. It's okay for tarting up chassis components which used to be rusty and might not have had any paint on them before but it shouldn't be used on exterior bodywork or anywhere that you expect to use other coatings such as wheelarches where you might want to apply a stone-chip paint.

[Bainbridge]

Here's my suggestion for the rear arches.

Use a wire wheel to grind back the lip to bare metal and grind away all the rusty bubbling areas.

Paint on a rust convertor to the bare metal areas and allow to do its stuff.

Brush paint on several coats of BH Electrox zinc primer.

You can then either paint over it to colour match your car, or leave it.

I have an MX5 NC and just writing this post has caused it to start rusting!

[Pica-Pica]

I would get it cleaned up properly and painted. My E36 2.5 went that way, and I wish I had caught it earlier. The E36 6 cylinders are great cars, and deserve protecting. For some reason, my front upper crossmember rusted away, despite all I tried to preserve it. Good luck. I had my 323i 4 door for 19 years and 145k miles.