Fighting and Winning the Rust Battle??

[ed1948]

Not my MCSS, but my new to me used 2006 Sierra. Hopefully the knowledge gained from this will help those with rust issues.
Re: fender lips where the outside panel and inside wheel liner are folded inwards and spotwelded. After a few years this folded and painted joint cracks and allows moisture to collect between the inner and outer metal leading to rust.
On my truck I would like to find an easy way to neutralize the rust and still leave a surface that paint will stick to.
The best way is to inject an oil based product to displace air and moisture. The problem with that is paint will not stick to oil the escapes the joint and the oiling must be repeated.
The question is: how to stop rust in an internal joint that allows repainting afterwards. Below is a pic, looking up at the top of the fender lip

I can easily deal with exposed surface rust but the hidden areas are a mystery.

 

[joesregalproject]

So for your situation, you want to stop rust without inhibiting your ability to repair later, correct?

Without causing adhesion issues later, you are pretty much limited to paint type products. Something like POR15 or another rust treating paint. I've used POR15 with some success and some failure. If I were to do it again, I'd go with brush-on Rust-Oleum.

You could possibly use a cavity wax as they are slightly less messy than oil coatings, but it still would need to be removed prior to painting and may be difficult to get off.

Me personally (as someone who has done bodywork for about 8 years), I'm Fluid Filming everything. I like the product, it has proven results, it's not expensive, and it's easy to apply. Yes it requires a recoat every year, and yes it is messy underneath the vehicle, but IMO greasy is a lot easier to fix than rusty. If I ever have to get it off later, soap and water seems to take it off, and if it doesn't, I'll figure something else out.

 

[bob64]

If it's a hidden area pick up a spray can of rust killer at CT, it's a clear spray that chemically changes the rust to a black paintable surface and stops the further rusting.
Just wire brush off loose rust and spray. I've used it underneath of cars where rust was just starting and seems to work really well.

It's made by Rust Check.

 

[ed1948]

As a temporary measure I tried running Phosphoric Acid through the three access holes near the top perimeter. It drained from both sides. The concern is dirt, debris and rust may be blocking fluid flow into the gap. It is something I can not check. I have flushed the upper wheel lip crease from the inside every which way including through the drain holes until the water drained clear. If the weather permits I would like to remove the wheel to allow pressure washer spray into the exterior part of the lip. Paint flaking off is not an issue because the truck had OEM plastic flares. I would also like to remove the fender braces to allow room for a peek over top of wheel house. In this vid check :38 secs - shows wheel house and three drains
\

 

[Streetbu]

You can never stop rust, only slow it down. I would rinse with water as best you can. Take care of painting the outside, then when the paint is cured, spray inside the fender with Fluid Film. It will need to be reapplied once a year. It will creep out and leave an oily stain on the outside but simply wipes off and won't effect the paint. You can't however use it before you you paint...

 

[ed1948]

I have used Fluid Film on my other vehicles which had 0 or very little surface rust.
Another issue is the body support welded channels from one side to the other - they have internal rust and rust at the spot welded joints.

I need to figure out how to remove loose rust from those channels and even some frame cross connecting tubes.
I need to get some flexible rustproofing spray wands for internal sections. Going to do a box off for the fuel pump and to easily attack the rust underneath.

 

[ed1948]

PS> I've seen worse underbody rust on these trucks during my search - an they were asking a lot more money for them.

 

[grandamman]

Here's what I did.
360,000 miles on that old junky TBI. I installed the hydraulic dump on

it 18 years ago.

 

[ed1948]

/\ = now that's a truck.
What holds the front down - a latch or gravity? 3/4 or 1T?

 

[ed1948]

Interesting pic of top of rear wheel housing. It's about time to attack = box off assuming I can loosen the box bolts.