How to Completely Seal a Rusty Fuel Tank

Rust in fuel tanks can create all kinds of havoc. A customer contacted us about the fuel tank in his 20-year-old diesel pick up, which had developed patches of flaking rust inside an otherwise shiny tank. Most of the rust spots were small, however, the largest was about 4”x10”. We were told flaking rust had found its way into the fuel filters, plugging them, which caused drivability problems. He cleaned out the tank and replaced the filters, but the problem happened again as the rust continued to progress.

After hearing about our Auto Fuel Tank Sealer Kit, he wanted to use it, but asked us if the tank sealer kit would completely seal a rusty fuel tank or was it just for repairing small rust patches.

What Causes Rust in a Fuel Tank?

Rust is caused by water trapped inside the fuel tank. But how does water get into the tank? The main way is because of condensation. That is, moisture in the air condenses on the inside of the tank. As water condenses on the tank surface that is not submerged in fuel it combines with oxygen and causes the metal to rust. Condensation is at its worst with high humidity and rapid temperature changes. An additional way water can get into the tank is when refueling in rain or snow and the precipitation finds its way in through the fuel filler.

Water pooling in the tank is another situation to consider. Water is heavier than fuel, so it can collect and pool on the bottom of the tank while the fuel floats on top. The pooled water can create rust, and this is what appears to have happened with our customer’s tank.

How to Avoid Rust in Fuel Tanks

As we described, water and oxygen combine with exposed metal and create rust. So, to avoid rust in fuel tanks the water and oxygen need to be separated from the metal. One way to do this is to keep the fuel tank full so the metal won’t be exposed to the air. Water won’t be able to condense on the submerged surface.

How to Stop Rust in a Fuel Tank

If your fuel tank has rust, there are two ways to fix the problem. You can replace the tank with a new gas tank, which can be very expensive, and in the case of some vehicles, a replacement tank might be difficult or impossible to find. The other option is you can seal a rusty fuel tank.

How to Seal a Rusty Fuel Tank

Basically, the procedure to seal a rusty fuel tank is to clean the tank, remove existing rust, and coat the inside of the tank with a sealant. KBS Coatings has a variety of tank sealer kits for different size fuel tanks, and each includes the necessary materials for cleaning, rust removal, and sealing.

Clean the Fuel Tank

This first step is to remove built-up gum or varnish as well as loose, flaky rust. For our customer, this was an especially important part of the process to seal a rusty fuel tank since the tank was having an issue with rust.

• After the fuel tank is removed from the vehicle, KBS Klean is used to clean the tank. KBS Klean is mixed with warm water and allowed to soak.
• The tank is rotated at intervals to be sure KBS Klean covers all the surfaces.
• To best remove rust, a mechanical abrasive, like a piece of chain, or nuts and bolts, are placed in the tank to help knock flaking rust loose.
• The KBS Klean is then drained, and the tank is rinsed thoroughly with water.

Prepare the Tank for Sealer

Now that the tank is clean, the second step to seal a rusty fuel tank is to prepare the metal to receive Gold Standard Tank Sealer. This is done with RustBlast, which is an acid metal etch that neutralizes existing rust, etches the metal, and leaves a zinc phosphate coating so the tank sealer can best adhere.

• The RustBlast is poured full strength into the dry tank.
• The tank is rotated every 5 minutes for at least thirty minutes to one hour to be sure all the inside of the tank gets etched well.
• A length of chain or nuts and bolts can be put in the tank to agitate and help remove the rust. That is what our customer did.
• The tank is then rinsed thoroughly with water.

Seal the Fuel Tank

The third step is to seal a rusty fuel tank is using Gold Standard Tank Sealer. To answer our customer’s original question; the KBS fuel tank sealer is designed to seal the inside of the tank in its entirety. Not just small rust patches. It will seal exposed metal as well as light surface rust away from water and oxygen. Also, if needed, it will seal pinholes and weld seams. Keep in mind it’s not necessary to remove every bit of rust before using the Tank Sealer, since it will bond to and permanently seal any remaining surface rust or corrosion.

• The entire can of Gold Standard Tank Sealer is poured into the fuel tank.
• The tank is slowly rotated so that the inside of the tank is thoroughly and evenly covered. This is done for up to thirty minutes.
• Tank Sealer is made to be applied in a single thin coat. It’s important to take time to thoroughly coat the entire tank well and be sure any remaining surface rust, leaky weld seams and pinholes are sealed.
• The remaining tank sealer is then thoroughly drained from the tank. It’s important to not let the remaining tank sealer form puddles as the pooled sealant can foam and bubble, which can affect its ability to adhere to the metal.
• Last, allow tank to air-dry in a well-ventilated area. Allow 96 hours for maximum cure.

After using the Auto Tank Sealer Kit, our customer found the inside of his tank was permanently sealed, rust free, and protected from future rust. Even better, there was no flaking rust to clog his fuel delivery system!

Please understand that this is just an overview. You will find Complete Directions HERE.

If you have any questions about the procedure to seal a rusty fuel tank using a KBS Tank Sealer Kit, please let us know by contacting us HERE.