StratfordShark

The only really bad bit of rust on my S4 is bubbling behind the rear left wheel arch.

Today I removed the splash shield behind the wheel there, to reveal very nasty rust on that panel. The photos are of the exterior bubbling, looking back into well with shield removed, and a close up of the rust. As you can see there's a kind of 'skin' peeling back/flaking off then below that the rust.

What's the best way to treat this? Before getting a bodywork pro to look at correcting the exterior, what can I do to remove rust and at least arrest decay at this stage, or at least slow it down? Any recommended products.

btw I know the exterior looks filthy but it's partly the flash, and partly just back from a long trip on winter roads and haven't cleaned off the grime yet. I realise that long term this is a cause of rust! usually my car is very clean.

Happy 2009 driving year to all my friends on Rennlist.

steaditim

What part of the country has this car spent most of it's life ?

Giovanni

Doesn't look like there would be a good treatment other than cut and replace ;-(

StratfordShark

It's been in inland areas of the UK (in the milder south of the country but that's relative - we Brits are cold and damp for most of the year!) for most of its life apart from a couple of years in France/Germany (again inland). That's going on the owner address records which I have going back to first registration. AFAIK it hasn't spent time in coastal regions.

It looks like the notch in the splash shield where it passes over the two rear panels can allow quite a lot of crud to accumulate along that join.

Rest of body very sound with a tiny bit of bubbling around filler cap area.

rawky

This is the sort of rust which made me rid of my 944 (Even worse than this). I'd let someone look at it and then see whether its a cut and replace, or a whole new panel. There's loads of places for new panels, like PorschApart and Douglas Valley Breakers.
Cheers

steaditim

Mine had something similar but not to that extent. When I got in there to deal with it, I found more up higher at the back where the rear bumper fasteners are. I can see the first lower locknut in two of your pics. It looks rusty as well. You should check that out.


It's a tough area to work in, but I was able to grind to bare metal, treat and spot paint.

Tim

WallyP

If you just want to stop the rust, there are products that treat the rust...

Here is one write-up on a couple of the products.
http://www.eastwoodco.com/jump.jsp?i...rID=412&KICKER

Scrape the failed undercoating off, scrape and brush the loose scale off, and treat the area. It will at least stop the rust until you can do the final repair.

Maybach_Man

Hi Stratfordshark;

im in the process of going over the whole of ythe underside of my car... its about the same as yours.... i've been getting rid of the rust with a wire brush in a dremel and bigger ones in a air drill. i then treat the areas with products from bilt hamber and then spray with primer and then topcoat with stone chip. If you want a tip you should look under the plastic cill trims if you have a s4, probably rusted out, ask me how i know!!!

Geoff

StratfordShark

Hi Geoff,

That's useful coming from someone in the same climate! Thanks for the tool tips.

By sill trims do you mean the plastic '928' kick plates? If so then I have dodged that bullet - I changed the driver side one last week and found no rust underneath. Maybe you meant another area I should check/clean up?

Tails

Wally P +1

I use a product caller Ferropro or Kill Rust, which (IIRC) is Phoshoric Acid and it converts the ferrous oxide to ferrous phosphate and neutralises the rust. I lived within a 100 metres of a coastal beach for many year and it has worked well for me on all my vehicles. As a rust preventative in areas hard to reach I use a deoderised fish oil in a aerosol can, an excellent rust preventer as it will also wick into all nooks and crannies.

You don't have to fully remove all the rust, suggest by wire brush or the tang of a screwdriver, only the loose stuff, as it will wick under the rust. When all loose rust removed then paint over the area and allow to dry. Once dried then start you preperation for painting, like filling pot holes with filler, then undercoat and final coat etc.

I believe Geoff means the plastic protector pieces that are fitted onto the S4 lower edges of the doors and the lower section of the front mud guards. To do your rear sections displayed in you photograph I would remove the rear plastic bumper and inspect all the joint areas for rust as well.

In addition I would also check all areas that remain damp for rust bubbles, around windscreen, around rear quarter pane windows, around the trim of the windows, inside the door especially at the bottoms and drain holes, under the mudguards especially where pannels join etc.

Tails 1990 928S4 Auto

Shark Attack

ospho. i think thats how you spell it

Ian928

I would suggest sandblasting and Epoxy primer before painting. If there is sufficient metal left that will stop further corrosion and come on, that is not a structural part of the car!

Tails

Shark Attack

What a "p" here or there?

Tails 1990 928S4 Auto

heliflyer

Hi Stratford,

I have always had good results with Fertan for dealing with rust.
Have a look here http://www.caswelleurope.co.uk/fertanmain.htm

Cheers

Maybach_Man

hi stratford
no the ones that tails said.. below the kick plates under the doors, another tip.... i borrowed a profesional steam cleaner and spent half a day cleaning the underneath and the arches (behind all the covers. this not only makes it easier and cleaner to work on...it will also blow away any loose rust so you can see where it is.any info you need 07957643517

geoff