unibody rust preventative?

I need ideas on battling rust inside panels.....or unibodies.

I don't plan on getting rid of this jeep anytime soon so I've been working on taking care of all my rust areas on my 89 and started wondering about all the areas inside the frame rails that cant be seen.

I remember seeing a thread where someone sprays used oil inside their frame anually,seems like a good idea until mud gets up in there.I also seen one of those 12v rust preventative things that keeps a positive charge on the frame supposedly stopping rust......gimmick?

What I was thinking about doing is powerblasting or steam cleaning all the dirt out of the frame rails and buying some of that spray on rust converter in bulk and using my pesticide sprayer to spray inside the rails and then following up with rustoleum or some other kind of rust stopping paint.I've also heard that ziebart is only to be used on new vehicles that dont have any rust....not a 20year old jeep.

Any input will be appreciated....

Not too sure with the spray on "rust converters" really. I have had rust come through on metal after being coated. I too am wondering on how to keep the rust at bay on my 99 XJ. Rust is starting in all the "seams" interneath and at all the mounting bolts/holes underneath too. I just tossed about 4 cans of rust-converter at the back half after a intense steam cleaning and a few days of drying in the sun. Hopefully it will slow down the rust.

On using oil for the underside... I always thought that the oil would trap in moisture. Seems that the water would displace the oil and the oil film would halt the evaporation of the water and lead to severe rust over time.

I *was* thinking on phosphoric acid and zinc in a garden sprayer and hosing my underside/rusty parts. That will convert the rust to iron-phosphate instead of iron-oxide. Pretty much locks the iron from joining with oxygen. But, it needs to be cleaned off and the painted to work properly. I don't feel like laying under my XJ with some denatured alcohol and scrubbing everything to remove the phosphoric-acid residue. What to do....

I too am open for ideas from people.

I think the way to go would be to find a sandblasting nozel that sprays in a
90* angle or even better a 360* radius on the tip of a wand that could be inserted into the frame rail.blow out sand with compressed air.Then using the same type of wand/tip coat with paint.

POR-15

Thats what I used the first time around on my floor board rust...followed directions and rust got worse after two years.It did not stop it!!

If you live in the salt belts RUST is inevitable. Here is what they do by me. Any sort of undercoating is bad, it traps water. Dont use a sandblaster on already rusty undercarriage. You will only be removing the good painted surfaces. We clean them up with a wire brush in the rusted area's prime then paint using the rock guard stuff on anything outboard of the frame rail. As far as in the frame rail do flush it out good clean out all the holes let it dry spray into holes with a good primer and a cheap paint. Make sure to flush them out after winter and reseal them every year. Have fun with the unibody and stopping the inevitable means putting them away during the winter and rain.

I would use a grinder and a wire cup, go easy and use a full face sheild, then a zinc primer. Go to an industrial paint supply not the rustoleum in a spray can at HD

Edit: actually if you have an industrial paint supply I would see what they recommend

Rust Converter stuff has never worked. I have tried and tried, it always turns out crappy.

POR-15 does work (extremely well) if you follow the instructions and prep the surface carefully. I have used it and several other locals have used it with good results.

The trick is to get it clean enough so whatever is left behind isn't a moisture trap. Then seal it, hot wax works well, though sand and whatever sticks to it.
I clean it, spot paint, then coat it. The stuff I use is a water based resin (actually an undercoating primer) made by the same people who make Loc Tite and unavailable in the states the last time I checked. The undercoating primer works just fine as a top coat.
Boiled linseed oil works well, it dries into almost a varnish. It's a thin fluid that seeps into most everything. Non toxic, fairly safe stuff to work with. Lasts three to five years.
If you trap dirt, salt or whatever under any coating and don't seal it completely, it will suck up moisture and can accelerate rust.
Butyl, tar and other coatings have a tendency to eventually flake and become moisture traps. Wax based coatings stay sticky and get worse in the heat.
Hammerite has a newer water based acrylic (I think) that seems to work well. They also have a primer that when combined with the water based paint sticks to chrome bumpers and tow hooks for at least five years that I can attest to. Hammerite is designed to paint over rust, though I do prep anyway ( I just don't prep as well as I normally would). Pretty good stuff actually.
Rust removal and preservation are really labor intensive, so I tend not to use the cheapest top coats available.
Boiled linseed oil is fairly inexpensive, though really dirty to work with, you need some big plastic sheets and waterproof clothing.

While I don't have to deal with road salt, I do face humidity, condensation, lots of frequent rain at times, etc. I have found that vehicles that set up, not used daily, tend to rust very fast, especially at seems and joints, which has something to do with the electron flux through the unibody while driving, versus storage. I have seen a lot of gadgets for corrosion control and I suspect that there are viable electronic hardware options that slow or stop storage corrosion by trickling an occasional current through the unibody. In fact I probably need to buy a few of them myself. The technology and application is sound!

People like NACE (National Association of Corrosion Engineers) are the experts on this, and big businesses spend billions of dollars on similar systems for things like ships, buildings, structures, bridges and so on that use various ways to set a up a voltage gradient or potential to stop iron oxidation. For big stuff these electronic corrosion control devices sell for hundreds of thousands of dollars, are very smart, computerized, NASA tech systems.

Since many of us store these XJs between uses it is something we should research product wise and find the best sources and brands. They can and do work, but like everything else there is probably some junk out there along side the good products, so we need to sort them out. Thre is probably a good system out for there for under $30 that we could use. I already use solar panels in my dash to keep the batteries charged during long term storage!

So far I have used the Permatex and Kleen-Strip (TM) rust converters that convert red rust into a hard iron oxide polymerized primer that is about the best rust and primer protection you can buy in my opinion (I work, engineer, in the industrial marine coatings area). BUT, any primer must be top coated to protect the primer! for long term protection. I have used a variety of things to fill big holes in the floor like fiberglass, and residential outdoor 35 year Acryonized Silicone Latex window caulk for seams and such, and then painted over them with paint or rubberized top coats (aerosol). I had a 78 Dodge that was rusting out in the window to sheet metal joints in 85 that I treated this way and repainetd the car with a $200 Earl Shibe paint job, and it was 10 years before the rusted areas started rusting again.

One last thought, does no good to stop the rust on one side if the rust is originating on the other side of the floor pan!!!!

8mud,

Your post reminded me that the places I never have any rust is where I have oil , tranny fluid, or diff. fluid leaks! makes a great rust preventative coating! All the rusted spots are always clean bare metal. Even the thick road dirt accumations under my fenders from around here seems to stop rust, LOL.

I think the Loc tite stuff is available here, but harder to find on the shelf.

There are 4 or more brands of the polymer based primer rust converters around now, that I think are all the same formula. They all are huge improvements over most bare metal primers but they run about $300 per gallon. But like any primer they really need to be top coated with an apropriate top coat for the intended use.

Cosmolene (SP?) is also a fantastic rust preventive if you can find it. I use to sell a MIL spec aerosol version of it to the offsire and Oil and Gas industry 20 years ago.

8Mud said:

The trick is to get it clean enough so whatever is left behind isn't a moisture trap. Then seal it, hot wax works well, though sand and whatever sticks to it.
I clean it, spot paint, then coat it. The stuff I use is a water based resin (actually an undercoating primer) made by the same people who make Loc Tite and unavailable in the states the last time I checked. The undercoating primer works just fine as a top coat.
Boiled linseed oil works well, it dries into almost a varnish. It's a thin fluid that seeps into most everything. Non toxic, fairly safe stuff to work with. Lasts three to five years.
If you trap dirt, salt or whatever under any coating and don't seal it completely, it will suck up moisture and can accelerate rust.
Butyl, tar and other coatings have a tendency to eventually flake and become moisture traps. Wax based coatings stay sticky and get worse in the heat.
Hammerite has a newer water based acrylic (I think) that seems to work well. They also have a primer that when combined with the water based paint sticks to chrome bumpers and tow hooks for at least five years that I can attest to. Hammerite is designed to paint over rust, though I do prep anyway ( I just don't prep as well as I normally would). Pretty good stuff actually.
Rust removal and preservation are really labor intensive, so I tend not to use the cheapest top coats available.
Boiled linseed oil is fairly inexpensive, though really dirty to work with, you need some big plastic sheets and waterproof clothing.

Click to expand...

Check out eastwoods coating. Someone did an independant test of both eastwoods and POR15 and the eastwood ended up being more durable.

http://www.loctite.be/tds/Terotex3000structure-black.pdf

This stuff has been around for 25 years or so, has stood the test of time and performs as advertised.

Eastwoods and Zero Rust are both good products. Zero Rust is the safest of the of all the treatments. NO ISOCYANATES.
You can pressure wash the inside of the "frame rails" to a certain extent. Use a strong degreaser and scrub up inside them as far as you can reach. You can make up some sort of brush to reach inside them. rinse them real well, and let dry. If you can find a way to get air circulating in them then do it.
ZR makes a pre wash, use according to directions, just don't get it on to thick. Trying to find a way to spray a treatment in the rails will be a challenge, but we live for challenge or else we wouldn't own XJ's.
DO NOT use any of the treatments right out of the can, alway put in another container and paint out of that.
I really didn't come across any rust (insdie the rails) to speak of when doing my floor pans, even though the pans and all surrounding metal were rusted beyond repair.
The alternative would be to degrease, dry, and "bedline"

Don't worry about the rust, just let it happen. But before a panel is totally destroyed use it as a mold to replace it with fiberglass. Eventually you'll have a fiberglass jeep and nothing to worry about.


If anyone follows this advice please post pictures so that we can see how it turned out.

Ive used alot of rust preventers and /or converters over the years. The best is POR-15 ,its all over my 87 XJ .