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SW20 Fuel Tank Sealing

228 Views 2 Replies 2 Participants Last post by  twophoenix00
Well, it's been a while since I've posted, and of course I still own my AW11s and SW20. After all this time I had to do the FP in my 91 turbo since I purchased it years ago, and well, the tank was rusty.

I did the Muriatic Acid method, and had it soak overnight since the 2-hour max time range wasn't enough for the 1:20 ratio I used for the entire 14 gallons. The next evening, I saw the results and was very satisfied, so, after draining the acid and neutralizing it with large amounts of baking powder, I gave it numerous rinses with soap and water, then soaked it with WD40 spray, where I could get it, and some Marvel Mystery Oil to prevent flash surface rusting. All this actually worked well, and the Acid, despite of the extra time, actually removed all the rust, which appeared more like barnacles stuck on an ocean dock post when I first saw it.

After all that I gave it a few rinses with Acetone, and then spent a few days drying this tank and that was mainly done after I got clever and used my house Dryer to get the job done. Basically, I attached the exhaust hose from the dryer to the Sender unit port on the tank and sealed it all up and let the hot air get it dry. The only thing to worry about on that method is getting lint inside the tank so, it's always good to clean the lint filter before doing such a thing.

So, after this detailed process which became a success, I am now at the stage of using POR15 sealer, to make sure this doesn't happen again, and from the way it looks so nice right now inside, I know that rust will come back with a vengeance, and this is the last hope for this tank to last through the years to come. I did also buy spray rust preventers, but it would be difficult to find a way to extend the aerosol nozzle in such a way as to get all the surfaces inside the tank. This means I will have to use this very expensive, like 70 dollars for a quart expensive, POR15, and use the tank roll method to do so.
Thing is, what about the plastic fuel carrier at the FP port, and then the back flow preventer at the filler port? I worry that this expensive filler will clog up the back flow preventer door flap, and just as well, have some negative effect with the plastic that will be difficult to get around using the rolling method. I also want to make sure I coat the top of the tank on the inside, as there was plenty of rust there too, and so I will have to turn the tank upside down to do so, and that may require hours of rolling just to make sure I get an even coat.

Anyone ever use this POR15 stuff, and if so, how did you coat the inside of the tank with it, and how did you prevent any puddling from happening while doing it? I know this liner is top notch stuff, and I am not worried about it flaking, however, I think it would be difficult to prevent puddling, and also difficult to keep this filler away from the plastics that are inside the tank. Maybe getting some filler on the plastic basket and back flow preventer isn't such a big deal, but I have never used a filler/sealer before so I don't want to risk 70 bucks trying it just yet. :)

***Edit Update: Just in case anyone else goes through this process..... I have a few things to mention during this de-rust and cleaning of the tank, in an SW20 MKII, and the same would also apply to any AW11, given that these tanks are close enough to partitioned in the same way. What I am realizing now, as I was prepping to apply finisher, is that I have not finished the whole tank yet, given that I could not garden hose pressure spray, each far end of the fuel tank, that are both divided at some point by a metal partition, between each port hole at the top of the tank. What I did not realize and neglected to do, is remove the two evaporators at the far ends, and the back flow preventer that is attached to the metal inlet hose that attaches to the filling end of the tank. Since I did a full muriatic acid soak, brimming to the top, I was able to loosen the rust on the surface metal, however, since I could not spray water hard at those surfaces, the rust appeared to just re dry and now I will have to do an end to end soaking, and I plan to use either concrete cleaner or CLR for a few hours on each end, then re rinse and wash, and get back to using my dryer to get it ready yet again, for the finisher. I am thinking I may be able to buy some kind of hand spray painter, that will have a flexible extendable nozzle that can spray around each one of these port holes.

The main thing I learned during all this, is that if you treat this fuel tank as x4 separate tank, divided by each partition, you can apply each acid bath dedicated to one partition at a time, and then clean and rinse in the same way. Then with this finisher, I have to apply it in this manner as well and try to get into each port hole and apply the finisher for each one, and ensure I don't end up with puddling, or empty spaces just as well. If I had done the cleaning in this manner, after the full tank acid soak, then I would have been able to get to this last remaining rust at the far end of the tank. Basically, I just neglected to remove the two end evaporator ports, and the filler tube port so I could gain access with my pressure wash garden hose and get it all out like I was able to do very well at the Fuel pump and sender unit ports.
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I responded a few minutes ago but it seems it may not have gone through or posted correctly.

This POR15 stuff says it is able to repel chemicals from gasoline and temperatures, and from using it I can see how strong this stuff is and how hydrophobic as well. I have enough still on my hands to show for that, and in the end I am happy with the results so far. This was a very messy process, and much of that is how I decided to seal this tank because I didn't trust the 'roll' method that many have done, more so with smaller tanks, and just as well, non mr2 tanks. I decided to think out the sealer with Acetone instead, and use my Prevail atomizer to spray paint the inside. The process became messy not just from leaks that occurred from my sprayer, but also from having to mix it separately in a jar that connects to the atomizer, and getting the right thickness down so it can work.

I was able to get all that figured out and the spray worked out very well, except that I still have a few bare spots on the top of the tank surrounding the ports for the Fuel pump, Sender unit, the two evaporators, and the filler port with its' back flow preventer. I will have to devise a flexible telescopic paint brush to get these areas, and I can dip directly into the sealer to do so, with no thinning needed of course.

I also re sprayed the outside of my tank with a rubber paint finish for water repellent, which now creates protection on both sides of this tank. I am pleased with the results from the Acid, cleaning, and sealing, but I think when I do my other two Mark1s I have lying around, I will see how much it costs for a professional shop to do the work. It was a good learning experience for sure, but lots of chemical waste to deal with and alot of time spent doing all the work. I dont want to have to do this again, or, do the work poorly so exposed areas still end up rusting, and due to that, I have spent almost 4 weekends trying to get this done right the first time. Of course now, if I did it again, knowing what I know now about this process, it would only take me a weekend at best to prep the tank.
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