Common Gas Tank Repair Problems

Plastic Gas Tank Repair

Find the instructional videos in the Video section of this site.

There are two obstacles that are not usually considered when repairing gas tanks. These issues are:

Gas will eventually eat through the epoxy adhesives commonly used to repair damaged gas tanks. Gas, diesel, oil, regardless of the octane/cetane levels, will not eat through any of our SI Structural Adhesives … ever. We have an ongoing lab test where bonds have been immersed in high octane gasoline for a number of years. Bonds have retained 100% strength.

Gas tanks, especially plastic gas tanks, expand and contract. Adhesives which become rigid when cured do not expand or contract. When gas tanks expand, rigid adhesives crack leading to gas leaks. Gas tank repairs, especially plastic gas tanks, needs to b able to handle the expansion and/or contraction that comes from 1) changes in temperature adn 2) adding gas. Tech-Patches expand and contract with the substrate, so small shifts in the shape of the tank are not a problem.

Common gas tank problems:

There are three possible problems with plastic or metal gas tanks.

• Pin hole leaks
• A crack in the tank
• A hole in the tank.

We will cover how to repair each problem for both plastic and metal gas tanks.

Pin hole leaks

Procedure for repairing pin hole leaks in plastic gas tanks

• Rough the area around the tank to below the sheen.
• Clean the area with any cleaner that does not leave a residue.
• Saturate the area with the Poly Prep.
• Warm the area with a heat gun or hair dryer to about 120 degrees F or, by touch, to just below hot.
• Run a bead of the SI adhesive over the pinhole.
• Spread the SI adhesive over the pinhole with a glue squeegee or any flat surface.
• Spray a light mist of the Activator/Accelerator on the SI adhesive.
• Repeat the last three steps two times.

Why this method works.

All plastic tanks are made from a polymer, usually HDPE. A polymer is simply a series of monomers. SI adhesives are monomers. When you add even low level heat, you speed up the molecules of the polymer and those molecules also belief. As a result of our testing, we believe that the adhesive becomes part of the molecular structure of the poly tank.

To make this repair, you need a Poly Kit. Link below.

https://tbbonding.com/product/poly-kits/

A crack in the plastic tank.

There are differenet issues with each common problem in tank repair. The issue with a crack is that even normal usage will cause the crack to expand. To stop

rack to prevent that crack from widening. If you do not drill a hole at each end, the crack will lengthen and leakage will result.

When there is a problem with a metal tank, there is often a loss of substrate due to corrosion.  Ideally, that substrate needs to be rebuilt to the extent possible.  Our Filler, used in conjunction with an SI adhesive, will rebuild that tank and the new structure will not corrode. A Tech-Patch must then be applied to the metal tank..

PTFE PATCH

The PTFE Tech-Patch is the best selection for gas tank repair. It is impervious to even high octane/cetane fuels. Learn about all of our patches and choose the one best suited for your needs.

Buy Now

• A Tech-Patch, sized to fit the problem. Patches come in sizes from 2″ x 3″ to 6″ x 24″ and can be cut to fit your problem.
• A Poly Kit (or higher) which contains:
  • SI Black, our thicker structural adhesive. Thicker to give you the control needed to apply a Tech-Patch.
  • Poly Prep, an adhesion promoter for polymers and poly plastics.
  • An Activator/Accelerator (AA), the AA is critical to the Process.
• A heat gun, hair dryer or other heat source.
• Glue squeegee
• Sandpaper
• Instructions

For Metal Gas Tank Repair

• A Tech-Patch sized to fit the problem.
• A Starter Kit or higher
  • SI Black
  • Our standard Activator/Accelerator (AA)
• Glue squeegee
• Sandpaper.
• Instructions

Repair steps:

1. Surface preparation is critical.
2. CRITICAL. If the problem is a crack, drill a small hole at each end of the crack.
3. The damaged surface needs to roughed to a polished surface. Start with a medium to coarse grit of sandpaper and finish with a 400 or 600 grit.
4. Make sure surfaces are clean. Use any cleaner that will not leave a residue.
5. Wipe the surface with a soft cloth.
6. Spray the surface with the Activator/Accelerator (AA). Let the AA dry.
7. Apply SI Black (is clear and dries clear) to the matte side of the Tech-Patch except for diagonal corners. Apply liberally, especially covering the area of the crack or hole.
8. Grab the adhesive free corners of the Tech-Patch.
9. Press the Tech-Patch onto the problem area. Grab will be quick.
10. Press the edges of the Tech-Patch down with your fingers.
11. CRITICAL use the glue squeegee to apply pressure from the center outwards on the Tech-Patch.
12. Glue down the corners with the SI Black.
13. Apply a bead of the SI Black to the perimeter of the patch. Spray with AA.
14. Visually inspect the Tech-Patch to make sure there are no problem areas.

1. Surface preparation is critical.
2. If the problem is a crack drill a small hole at each end of the crack.
3. Aggressively rough the surface with medium grit sandpaper. 
4. Clean the surface with any cleaner that will not leave a residue.
5. Wipe the surface with a soft cloth.
6. Saturate the prepped area with the Poly Prep.  Let the Poly Prep dry. Once a poly is primed with Tech-Bond’s Poly Prep, that poly is primed forever.
7. Spray the prepped area with the Activator/Accelerator (AA). Let the AA dry. Once sprayed with AA, you have an hour of work time.
8. Warm the prepped surface with a heat gun or hair dryer.  Warm until the surface is just below hot, approximately 120 degrees F. 
9. Liberally apply SI Black to the matte side of the Tech-Patch except for diagonal corners. Make sure edges of the crack of hole will be covered with the SI adhesive
10. Grab the adhesive free diagonal corners, apply tension and press onto the problem area of the tank. Grab will be quick.
11. Press the edges of the Tech-Patch down with our fingers.
12. CRITICAL. Use the glue squeegee to apply pressure on the Tech-Patch from the center out.
13. Glue down the corners with the SI Black.
14. Apply a bead of SI Black to the perimeter to the perimeter of the patch. Spray with AA.
15. Visually inspect the Tech-Patch for problems.