The cure for rusty-tank syndrome

It’s one thing to have to fight rust that is easily accessible, like on floor pans or quarter panels, where it isn’t too hard to get to the problem area.  Nothing is worse than restoring a vehicle, only to find that the fuel tank you have in it is full of loose rust and coated in varnish. I recently fell victim to this exact problem with my VW pickup truck project. I had gone through quite an extensive job in getting this truck to the stage where it was almost drivable, only to be stopped dead in my tracks. If you are unfortunate (or masochistic) enough to have to go through this process, I decided to do a fairly universal “how-to” pictorial of how to go through this process.

Now, faithful Eastwood readers, I feel that we are good enough friends that I can tell you “how it is” without sugar coating it. This job is going to be messy, dirty, and downright unpleasant. You have to figure, if the gas tank on the inside is rusty enough to cause an issue, the exterior of the tank and it’s mounting points have to be that much worse. I found that that was exactly the case on my truck. It seemed like everywhere I looked, under the bed of the truck had surface rust, the outside of the tank being the worst of it for sure. As I dug into it, I found I really had to work to coax the nuts holding the gas tank straps to come off. Luckily I had grabbed a can of CRC Freeze-Off before starting on this. We just started carrying this product, and I will admit, I was a bit skeptical to say the least. I mean, come on, it “freezes” the rust off? But J.R. from our R&D fame assured me that it was the cat’s meow as far as rust fighting penetrates go. So I doused the threads on the stud, and the nut itself, a few times with the freeze-off, and let it sit. After working the nut back and forth, a little tapping with a small hammer, and some baby-talk to it, I was able to get both nuts to thread off with out breaking a stud or having to cut the nut off. I would say that the freeze-off gets my approval!

After assuring that I didn’t have to cut off any nuts or mounting studs, I removed the fuel pump lines, the fuel filler hose to the tank, and any associated breather hoses. I then dropped the fuel tank down out of the truck. I’ve found that your average floor jack is perfect for this job. Once the tank was out, I set it on a fender stand to work on it (not before cleaning the acorns off the top of the tank!). I started by draining the fuel out completely. You can see from the picture of the pre-pump filter, and also of what was left in the drain pan, just how bad the rust and dirt inside the tank was. This was the 4th fuel filter in a matter of a week. Each time I would attempt to drive the truck and hit a bump, the filter would get clogged with more rust. Also note the pictures of the inside of the tank that I shot, if you look closely you can see the piles of rust still in the tank, along with all of that varnish! I tried to knock all the major rust off of the walls of the inside of the tank by dropping some old chain into the tank and shaking it around for a few minutes (I told you this wasn’t going to be fun!). Follow all of this up by spraying the pressure washer inside of the tank, trying to flush all of that rust you knocked loose out of the tank.

After getting the tank out and drained, I realized that I wasn’t going to be able to just use our tank sealer kit and restore the inside of the tank, I was going to have to do something about how the outside looked. I decided to choose our Tank Tone Kit. This kit is made to help treat and convert surface rust on the outside of the tank and then you apply a silver coating that is fuel resistant and leaves the tank looking like the day the vehicle left the showroom. I needed to first, assess the corrosion and make sure that I wasn’t attempting to restore a tank that possibly would rot out and leak after a year or two. I hit the tank with a wire brush and a metal scraper to get all of the heavy stuff off first. After checking the tank for any thin spots, I started applying the rust converter that is included in the kit. Luckily I have a small 10 gallon tank in that truck, so only one tank tone kit was necessary. I would suggest at least two kits for an average full size car or truck. Because of how extensive the rust was on the outside of the tank, I let the rust converter sit on the tank for a full 24 hours.

I took pictures below showing how the converter progressed over this time. The last pictures you can really see how the surface has changed color of the rust all over!

Here is the rust converter working after only a few hours on the rusty tank.

Now here is after 24 hours with the Rust Converter working on the tank. Notice how much more of the rust has now been turned to a blackish purple color. The outside of the tank is now ready to be primed and top coated!

This is where the process of restoring an old gas tank really begins to make you rethink why you are doing this project yourself, but I can assure you… if you stick with me, the end result is surely worth it! I used one of our Tank Sealer Kits For Cars, again two or more kits may be needed for larger tanks. I plugged the openings in the tank using tin-foil and appropriate length screwdrivers. This kept the chemicals from getting all over the place. The first step is adding a bucket of our metal wash, which has been diluted with two gallons of hot water. You then shake, and turn the tank to get the metal wash to soak into all surfaces and etch the metal. This is a process that you will be very, very good at by the end.

After draining and rinsing the tank out, you follow up with a small amount of muriatic acid diluted in a half gallon of hot water. This acid is NASTY stuff, the bottle was smoking when I opened it… that is always a sure sign that this is not a chemical that you want to get on your skin! Again, mix the acid with the water, dump it in the tank, slosh the tank, drain, rinse. You can see how brown and contaminated the liquid coming out of the tank was still at this second step.

At this point I tried snapping a photo showing how the inside of the tank was beginning to be etched and brought back to clean metal. Pretty neat to see, but tough to photograph!

In the next step, you dump an entire bottle of fast etch in the tank again, to clean and etch. Once you have drained that all out, you add one small can of Acetone to clean the surface, and help evaporate any other water in the tank. Each of these chemicals are the same as the others, dump in the funnel, slosh around in the tank, drain out.

After I got the majority of the acetone out, I let the tank sit upside down for an hour to let the chemicals evaporate inside. I then used 1.5 bottles of the tank sealer and sloshed it around in the tank. This time I took much more care, making sure all of the surfaces inside were covered and the sealer wasn’t puddling or filling the center baffle. I let the tank sit upside down to avoid this and it also allowed the top of the inside of the tank to get some coverage.

The sealer fumes are very intense, I got too close and accidentally breathed in the chemicals when trying to shoot the photo of the inside of the tank, and it made me gasp and nearly faint. The lengths I go through to get everyone a thorough DIY article took their toll that night! Crazy stuff. Subsequently I got a headache later on in the evening. Moral of this story is, DO NOT under any circumstances, breathe in, or inhale the fumes coming out of the tank after the sealer has been applied!

The instructions then called for you to put an air nozzle in the tank and run it at at a low PSI to help dry the sealer and stop it from puddling too much. Since I don’t have an air compressor at my home garage just yet, I decided to rig up the exhaust on the shop vac to circulate air inside the tank. I left it on for about an hour, and it definitely seemed to do the trick.

Once the tank sealer had dried and there were little to no fumes remaining, I applied the Tank Tone to the outside of the tank. This really made a world of difference. I still have trouble convincing friends this is the same tank!

As they say in the repair manuals, “installation is the reverse of removal,” so I lifted the restored tank back up into the truck. Luckily it all fit back into it’s home pretty easily, and I was left to admire my handy work, and reflect on the restoration process . As many can relate, sitting back and admiring your handy work can be a catch 22… while it allows you to appreciate the end result of the hard work you put into restoring something, it also allows you to see the imperfections and faults in everything around it! I now noticed all of the suspension parts, and brackets under the truck that had minor surface rust on them. Not to mention the spots on the floor beds of the cab where I had applied our Brushable Seam Sealer and I felt like those spots needed some undercoating to give that OEM finish back to the floor boards, and match the fresh look of the gas tank.

So that begun the process of again using Rust Converter to treat and convert all of the surface rust, as well as prep the surfaces for top coats. I sealed the treated areas with Rust Encapsulator, and followed up with a top coat of our Satin Extreme Chassis Black. I felt this gave the undercarriage parts a nice understated “OEM” finish, and also gave me the piece of mind that the rust wouldn’t be coming back to haunt me years down the road!

All in all, this was a very tedious, long process. But, I am happy to report that since restoring the tank, the truck is now running well on its new engine, and is very close to being road worthy! I can’t wait to hear what the exhaust shop thinks of the undercarriage of the truck when they build my custom exhaust this week!!!

Keep up the hard work, and as usual, any and all comments, questions, and advice are welcomed here if you leave a comment!!



  1. I just spent the last 3 hours dropping my exhaust and the fuel tank because this coating was coming off in sheets. I was trying to drain the tank to only find that it was glogged almost solid. After getting the fuel out i dropped the tank to find a complete mess inside. I now have to try and clean out the old coating so I can send it out to be properly treated. The coating was only in the fuel tank for around 4 years. I would seriously rethink using this on your own car.

  2. If your attempt at doing this has failed it most likely failed due to NOT doing the prep correctly. A lot of folks have a problem with being patience and try and hurry a project along thereby getting the peeling of the sealer. This is the same as with any project the prep work always takes the most time BUT is the most important step one takes when repairing/restoring something. Great article Matt !

  3. Wouldn’t it be much easier and perhaps even more cost effective to buy a new tank?

  4. I have done this and I felt like that I had the arms of a gorilla when I was done. Here is an idea for R&D…Create a stand that rotates the tank in more than one direction to distribute the chemicals. I envision one of those rides that spin you upside down and sideways at the same time. Perhaps a motorized version too.
    Just a thought.
    Thanks for the great article.

  5. In many cases like this you can’t get a new tank for the vehicle so saving it is the only option.

  6. Your article was very timely. Ethanol blended fuel is more hygroscopic that 100% gasoline and exacerbates tank rusting – especially if the vehicle is stored with the tank partially filled. I know it is hard to justify letting a car sit full of gas that is destined to go bad in 3 months or less, even with stabilizer. My experience with inside tank coatings is that they will fail if there is any uncoated area that fuel can creep into. Don’t skimp on product or prep. Like a pretty paint job over wax or oil laden surfaces that is destined to peel, so will the coating if the tank is not completely and properly prepped! Any remaining rust will continue to expand and eventually crack the coating resulting in flaking off. There is nothing wrong with your product, the fault is with well intentioned folks that take short cuts! MEK is somewhat better than acetone for gum and varnish removal. Muratic (hydrochloric) acid is used for cleaning mortar from brick. It is nasty stuff and every possible precaution must be used when using it for any purpose. NEVER add water to acid. ALWAYS add acid to water to reduce fumes. Surface oxidation will form quickly after the acid wash so don’t let the tank sit around before the next step. Keep some baking soda & water solution handy while using the acid in case some gets on your skin or spills Dissolved rust will raise the pH of acid rendering it ineffective so a second or even a third application may be needed if you have a lot of rust in your tank. Remember, the fumes are also corrosive and can cause burns. I have restored many old rusty tanks and have NEVER had a coating failure – but I am anal about a good prep just as I am with my paint jobs. Thanks for sharing your experiences with your Vee-Dub tank.

  7. As mentioned there are no new tanks made for this vehicle so good used tanks can be $3-500 for a good used one.

  8. I have heard of this before, quite a long time ago. It seems to me that the procedure was, after cleaning a gas tank, to add baking soda to water in the tank and then apply an electric charge. Does this process coat the inside of the tank with low-carbon steel?

  9. Great article, Matt! Thanks for the insight. Although I don’t have a tank to restore at the moment ( I just purchased a new one got my 67 Mustang project, I am interested in the frame and undercarriage rust prevention/treatment you briefly alluded to. Would you say the rust conversion, followed by rust encapsulation, then prime and paint is a good method to follow for frame, leaf spring, cross members, etc.?

  10. Guys if u acid clean the tank to bare metal. This stuff works. I’ve been using it for. Years

  11. I’ll just buy a very nice quality fuel tank brand new from my favorite restoration parts companies… I can skip all this time and hassle that way. If you have a vehicle that you cannot buy a new tank for, I would say go to a professional company to let them take care of it.. Just doesn’t sound worth all that time and hassle to do yourself.. Why???

  12. with the electricity – The rust is being reduced from iron oxide to iron and falls into the solution. The nail is a sacrificial electrode and the baking soda an electrolyte and pH conditioner. There will be no gain of metal to the tank. Once the oxidized metal is converted from rust, and if the “clean”surface metal is treated/coated/painted, then it will be protected from new rust forming.

  13. Will the Eastwood products work for a large water tank. (approximately 180 to 200 gallons) I am restoring an old fire engine and before I put the booster tank back in , I want reseal it.

  14. You would need a LOT of kits as these are packaged for small automotive tanks. The other problem is sloshing the tank to make sure the product has even distribution.

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