The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →For a small leak in a compatible metal tank, choose a repair product explicitly labeled for metal fuel tanks and keep the damage within its stated limits. The Permatex Fuel Tank Repair Kit (item 9101), Permatex Fuel Tank Epoxy Putty (item 84334), and J-B Weld TankWeld are options with different formats, size limits, and cure times. Those figures are manufacturer specifications—not independent proof that a patch is safe for every leak.
Which epoxy is best for a metal gas tank?
There is no independently established “best-performing” product among these options. For a small leak that fits its instructions, the Permatex 9101 kit is a purpose-made kit for metal fuel tanks; Permatex explicitly excludes plastic fuel tanks. The 84334 putty is another localized-repair option for metal gas tanks and containers. J-B Weld TankWeld is a kit specified for metal and fuel storage containers.
Choose by tank material, damage size, repair format, and the time you can leave the tank out of service. Product-page claims such as “permanent” are the manufacturers’ descriptions, not comparative test results.
Compare the three products
| Product | Manufacturer-stated fit and damage limits | Timing and important limits |
|---|---|---|
| Permatex Fuel Tank Repair Kit, item 9101 | Metal fuel tanks; not plastic fuel tanks. Specified for slow-leaking cracks up to 4 inches and holes up to 3/8 inch. | Product page states resin cures in 30 minutes. Supplied resin begins hardening in 8–10 minutes; instructions say to mix and apply in less than 8 minutes. Ideal repair temperature is 50–75°F (10–25°C); lower temperatures extend cure time. |
| Permatex Fuel Tank Epoxy Putty, item 84334 | Metal gas tanks and containers. Does not adhere to polyethylene or polypropylene. | Sets in 1 hour, is machineable in 5 hours, and fully cures in 24 hours. Fuel resistance is stated after full cure. Not intended for structural bonding. |
| J-B Weld TankWeld | Metal and fuel storage containers; not polyethylene or polypropylene. Manufacturer lists cracks up to 4 inches and holes up to 1/4 inch. | The reviewed TankWeld product specification does not state a cure time. |
The Permatex 9101 damage limits are for slow-leaking defects; they should not be treated as universal safe-repair thresholds. TankWeld’s 4-inch crack and 1/4-inch hole limits are also manufacturer specifications, not independent validation.
#1 Best Overall
- Hand-mixable, steel-reinforced, non-rusting epoxy putty that quickly repairs or rebuilds anything made of metal
- Great for gas tanks, radiators, lawn and garden equipment, water tanks and all metals
- Sets in 5 minutes and fully cures dark grey in 1 hour with a tensile strength of 900 PSI
- Once cured, it can be drilled, tapped, machined, ground, filed and painted and will withstand temperatures up to 300ºF
- J-B Weld is proudly made in the USA
How to repair a leak with the Permatex 9101 kit
Use the instructions on the current package for the exact product in hand. Permatex’s product directions give the following preparation and application requirements:
- Work with adequate ventilation and remove the gas cap for ventilation, as the kit instructions direct.
- If the leak is large, reduce the fuel level below the damaged area before applying the repair material.
- Remove dirt and other contamination from the repair area.
- Sand at least 1 inch beyond the damage, then wipe the area with an alcohol swab.
- Mix and apply the supplied resin in less than 8 minutes. The resin begins hardening in 8–10 minutes, so do not treat the stated 30-minute cure as extra working time.
Permatex specifies an ideal repair temperature of 50–75°F (10–25°C); curing takes longer at lower temperatures. The manufacturer’s 30-minute cure statement applies to the kit’s resin and instructions, not to the other products in this comparison.
Rank #2
- TANK WELD: Our Metal Fuel tank repair kit has all you need for making professional quality, permanent repairs with state of the art components and easy to follow instructions.
- THE ORIGINAL COLD WELD: JB Weld was developed as an alternative to traditional torch welding. Designed to be extremely effective in harsh environments, once it sets, it's tougher than steel.
- SIMPLE TO USE: No removal of gas tank is required to stop leaks. Easily fix holes up to 3/8" diam. or cracks up to 4" long. Includes epoxy putty, fiberglass cloth, sandpaper, and applicator.
- VERSATILE & DEPENDABLE: Great for gas tanks, metal tanks, oil pan repairs and more. Professionals, mechanics and avid DIYers know J-B gets the job done.
- NO PROJECT TOO BIG OR TOO SMALL: We have all the products you need to get the job done right. JB Weld always delivers the legendary performance of the World's Strongest Bond.
Using the Permatex 84334 epoxy putty
Permatex directs users to clean off grease or dirt, wear gloves, knead the two parts until they reach a uniform color, and apply the putty within 30 minutes. The manufacturer states a 1-hour set, 5-hour machineable time, and 24-hour full cure. Do not refill or return a repair to service on the assumption that “set” means fully cured; the listed fuel resistance applies after full cure.
The putty is not intended for structural bonding. Its metal-tank description does not make it a remedy for structural damage or extensive corrosion.
Rank #3
- Manufacturer: BLUE MAGIC
- Country of manufacture: United States
- Part number: 6522KTRI
- Included components: Unit, Instruction Guide
Do not transfer another product’s directions or cure time
J-B Weld’s gas tank repair guide describes a SteelStik procedure: mark the leak, sand to bare metal, clean, knead the putty to a uniform color, press it onto the leak, and allow at least an hour before driving. That guide concerns SteelStik, not TankWeld, Permatex 9101, or Permatex 84334. Follow the current instructions for the product actually being used.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Safety and when a patch may not be appropriate
A patch is not automatically suitable just because a defect appears small. The manufacturer guidance reviewed covers specified small defects; it does not establish that epoxy is appropriate for extensive corrosion, structural damage, a large or active leak, or every location on a tank. Seek professional assessment when damage falls outside the chosen product’s stated scope. Do not attempt to weld a fuel tank based on this repair guidance.
Rank #4
- 【Excellent High Temperature Resistance】: Fuel tank repair adhesive can remain stable between -50 ℃~180 ℃,high and low temperature resistance,with stable and excellent repair effect under extreme temperature
- 【Long-lasting adhesive strength】: Made of high-quality materials, the cured repair effect is strong and maintains a stable permanent bond to ensure longevity. Suitable for repairing ruptures,cavities,sand holes and rust corrosion and other problems
- 【Excellent quality】: High hardness of fuel tank repair adhesive after curing can be sanded on the repair surface,wear-resistant and corrosion-resistant,waterproof and oil-proof,pressure-resistant and impact-resistant
- 【Easy to use】: No need to dismantle the tank to plug the leak. Before use, please clean the surface first. Then use a pusher to push the appropriate amount of adhesive to the repair surface, and stir with a mixer to mix evenly, and finally apply it to the surface,after 24 hours of complete curing
- 【Wide application】: Suitable for fuel tanks,water tanks,stainless steel water tower,stainless steel water tanks,oil drums,metal fuel tanks,oil sump repair and so on
Permatex’s 84334 safety data sheet, revised 12 February 2024, identifies skin irritation, serious eye irritation, skin sensitization, and suspected carcinogenicity hazards. It calls for protective clothing, gloves, and eye protection or a face shield, and says to avoid breathing dust, fumes, gas, mist, vapors, or spray. The 9101 kit instructions separately require adequate ventilation. Check the current package label and safety data sheet for the product you use.
Quick Recap
Best Value
- Two part, hand kneadable, putty type epoxy stick used for repairing metal gas tanks and containers
- Contrasting colored materials are mixed together to form a uniform color to indicate thorough mixing
- No tank removal required; sticks to gasoline wet metal
- Cured adhesive can be drilled, sanded, threaded or filed; resistant to fuels and most solvents after full cure
- Suggested Applications: Gas tanks and gas cans
Manufacturer sources
- Permatex Fuel Tank Repair Kit (item 9101)
- Permatex Fuel Tank Epoxy Putty (item 84334)
- J-B Weld TankWeld
- J-B Weld gas tank repair guide (SteelStik procedure)
- Permatex 84334 safety data sheet
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
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