944Time

What is the proper approach to this? Wire brush and sand down to bare metal, then prime?

It doesn't have to be perfect, I just don't want it to get worse.



Rust!

PetePorsche

Hate to say this, but that looks nasty. My experience is that once you start removing rust like this you're gonna end up with revealing more and more rust under the paint.
The proper approach - sadly - is the most expensive one. And that will be first of all to open the doors on the car (i'd check both sides), and remove the little black plastic vent in the sill. Peak inside with a flashlight and see how bad it is on the inside. After that clean the rust by sanding the spot down to see how far the rust has went under the paint. Do not use a wire brush and do absolutely NOT use a wheel wire brush on an electric grinder. This will cause huge holes if the rust has gone too far. I like to use a electric sanding machine with round pads, just working through the paint to bare metal very slowly.

I hope the insides don't look too bad!
Sorry to say this but there's no easy way out.

944Time

I never thought of looking at it from the inside.
It looks like those door vents have a release tab on the top.


Well, thankfully the metal is nice and firm on the inside. The rust is just on the surface. I don't want it to progress to rotted-out!


BTW, what is wrong with wire wheel brushes?

V2Rocket

wire wheels can be very aggressive.
if the rust has thinned out the metal significantly you can burn a hole in the car very fast.

951and944S

Yes, pull that door jamb vent and with some good LED lighting, inspect it from the inside.

There is a weld seam (vertical line in your pic) that attaches the rocker panel to the 1/4 panel so it's very possible that the damage is isolated to the 1/4 panel.

Assuming that this is the case, here is what you should do.

Use the defined area of where the lower 1/4 panel's chip guard is applied (also called rock guard), you can see this by the horizontal line where it was originally applied.
Run a horizontal tape line very accurately.
Using a razor knife with enough pressure to reach the body metal, cut horizontally along your tape line.
Using a razor scraper (type with screwdriver handle) remove all chip guard, paint, etc. You will be left with the rusted area and some bare body panel with factory sealer.
Using a spot sand blaster, thoroughly blast away all rust, focus just on the rust, not the still good factory sealer area.
These type blasters (you can get a cheap one from Harbor Freight) have rubber attachments that you press against the rusted metal and contain all blasting effect within the rubber blast head/cup.
Clean remaining body surface beneath your tape with 3M Adhesive remover and lint free towel (blue paper towels).
Tack dust and lint away with a tack cloth.
Apply 2 coats of acid etching primer or 2 part epoxy primer.
There will be pits and divots in the originally rusted area so you might want to consider epoxy, as you can make one pass with a thin coat of body filler over the epoxy but it's not tecommended to put body filler over acid etching primer.
Let work cure for 24-48 hours.
Sand/rough up with 180 grit paper.
Remove old tape/line.
Apply new tape in exactly same spot (by now your old tape is contaminated)
Apply 2 coats of TranStar Tex Coat/Chip Guard after prepping area clean again.
One coat of primer sealer (since you now have it, epoxy is excellent here also.
Apply 2-3 coats of single stage enamel/urethane.
If you roll back 1/4" of your lower tape line away from body and aim upwards on your spray coats you will be able to wet sand before buffing later and probably never see the line where your work began/ended.





T

951and944S

Wire wheel will hit the high surface.

You need head on penetrating media, i.e sand, glass bead, soda, etc.

T

T&T Racing

T,
Have you tried chassis saver to chemically "lock up" the rust?
Tom

harveyf

T's approach is very comprehensive. If you are very short on funds and just want to hide the problem (from 10 feet away), I would suggest POR-15, followed by a topcoat of the closest matching spray paint, such as Duplicolor. You would literally apply the POR-15 direct to the bad area. Repeat a few times. Paint with color. Don't get me wrong, this will not fix the problem but will hide it for a few years. The texture will be wrong and the paint will probably not match. It just depends on your long term plans. POR-15 is very tough stuff. Get some on your hands and see how long it takes to wear off

T, I know you are rolling your eyes Just trying to give the guy some options.

951and944S

'Rust Never Sleeps'

- Neil Young

951and944S

LoL, no, not really.

I know this stuff...., my father-in-law ran a body shop for 30 years and I have a lot of friends in the body business.
I do all my own.
My first job was wet sanding cars at a show car body/paint shop after school when I was 15.

I know you know enough about it to know what I was explaining was correct but there is always more than one way to skin a cat (who would skin a cat and why is that even a saying.. ) so yeah, it's basically a choice of the owner which route to go considering his own goal.

My role here is to share what I know, that's all.

T

T&T Racing

IMHO, T's comprehensive approach is the "gold standard" ..my comment on the chassis saver was to seek his opinion and I'm not endorsing it as an approach.

944Time

Ok, I decided to go the quick 'n' dirty way.

Used a wire cone...did not go thru the panel.




After wire cone-ing



Half-baked masking





Hand-held cardboard shield.




First Coat




Second coat, and tape removed. A little bleeding, a little over spray.

I have to wait 72 hours (3 days?) for curing.

NelaK

Just a helpful tip for when you're blending the paint - a piece of paper folded over gives a nice 'soft' edge. You can see what I'm talking about in the following video:

FrenchToast

FWIW, it's very likely the metal is rusted on the inside and you just didn't see it. Even if the car is forever in a desert they typically rust from the inside out in the rear of the rocker panels.

You can't see that specific area unless you pull out the carpet, pull out the access plugs, and use a scope.

Best fix is to cut it out and weld in new metal.

peanut

I hate to say it but if there is that much rust showing on the outside then its going to be a whole lot worse on the inside out of sight. he sills on these cars rust from the inside out .


The best rust inhibitor that there is is oil .........

If you look under any car where there is any oil leaks ....you will never find any rust ever !

Five years ago my car had some rust showing like yours so i mixed some oil and grease together with a little diesel and then brushed it into my sills via the door vents and it held the rust at bay for 4x further years.

You could use a rust converter like Vactan which will convert the rust but nothing works as well as oil .

I would say that your best bet for an acceptable bodge would be to cut out a 3-4" hole in the rusty patch so that you can get in and treat the rust . Then pop rivet a small metal patch repair piece over the hole and fill and sand it down flush and once painted you'll never know it was there. That should hold for a few years.