10 Best Epoxy for Plastic Radiator Repair [Reviewed in 2021]

Leaking radiators is one of the most common problems that affect automobile engines. If a radiator leaks, coolants will be lost, leading to overheating, causing transmission failure, in worst cases, fire hazard.

When a radiator leaks, the ideal solution is to change the radiator, which costs a lot of money. However, before replacing the leaking radiator, there’s an alternative way to make repairs to it without spending a fortune, and that’s by using epoxy.

best epoxy for plastic radiator repair

Using epoxy to repair a damaged plastic radiator will save you from spending a lot of money, especially when the crack in the radiator is minor.

In this article, we will provide you with well-detailed reviews of the 10 best epoxy for plastic radiator repair with their benefits and drawbacks outlined alongside them.

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OUR RATING

PRICE

K-Seal ST5501 Multi-Purpose One Step Permanent Coolant Leak Repair

4.9/5

J-B Weld 2120 Radiator and Plastic Repair Kit

4.8/5

RapidFix UV Liquid Plastic Adhesive

4.8/5

Permatex 84145 Permapoxy Black Plastic Weld

4.7/5

Blue Magic 6522KTRI QuikSteel Plastic Tank Repair Kit

4.6/5

Our 10 Best Epoxy for Plastic Radiator Repair Picks:

1. K-Seal ST5501 Multi-Purpose One Step Permanent Coolant Leak Repair

Having a leaking radiator is a nightmare for most car owners because it costs a lot to replace. However, with the K-Seal ST5501 multi-purpose leak repair, you don’t need to replace the radiator. This is because it offers a one-time permanent solution to leaking radiators. Not only does it seal leaks in radiators, but it also works for engine cylinder heads, head gaskets, water pump casings, and heater matrix. It repairs cracks and holes as large as 0.635mm.

The K-Seal ST5501 multi-purpose leak repair is compatible with all antifreeze. It doesn’t react with coolants or other chemicals in the radiator. So, you don’t have to drain or flush the radiator before using it. This product works the same on a cold or hot engine. Nevertheless, while dealing with a hot engine, exercise caution. It comes in an 8fl oz container that can treat up to 12 cylinders with a capacity of up to 20 liters.

Using this product is very easy. Shake the container thoroughly, pour the fluid into your radiator and leave the engine idling for about 20 – 30 minutes.

Note that if it doesn’t seal your engine head gasket leak, then your system is over-pressurized. To solve this problem, disable the problem-causing cylinder temporarily by removing the spark plug in a petrol engine or the glow plug for a diesel engine before pouring the K-Seal compound. However, if the damage to the head gasket is severe, this product may not repair it.

Benefits

  • It permanently seals leaks in block radiators, engine cylinder heads, head gaskets, water pump casings, and heater matrix.
  • It requires no mixing. All you need to do is to shake and pour, then warm your engine, and the leaks stop.
  • This product is compatible with all antifreeze and will not affect your engine efficiency.
  • It works the same for both hot and cold engines.

Drawbacks

  • It doesn’t work on radiators with severe damage.
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2. J-B Weld 2120 Radiator and Plastic Repair Kit

The J-B Weld 2120 radiator and plastic repair kit come with everything you need to make professional quality and permanent repairs to your radiator by yourself. It is meant for radiators made out of plastic but can also repair aluminum and copper-brass radiators.

This radiator repair kit includes a waterproof, heat-resistant epoxy putty, fiberglass cloth, sandpaper, and applicator. All you have to do is mix the quantity you want in a container, then apply it to the affected area of your radiator immediately after mixing. Also, ensure you use gloves when applying it because it produces a lot of heat when mixed.

With the J-B Weld 2120 radiator and plastic repair kit, you can close holes up to ⅜” in diameter and 4” long cracks without stress. The only downside to this epoxy is that it has a fast set time (1 – 2 minutes), making you work in haste. So, don’t mix all the content at once.

Benefits

  • It permanently repairs 4” long cracks and ⅜” holes in plastic radiators.
  • Everything you’ll need to make repairs to your radiator is included in the package.
  • The epoxy putty that comes with the kit is waterproof.

Drawbacks

  • It has a fast set time.
  • It produces high heat when mixed, so you need to wear gloves.
CHECK PRICE ON AMAZON

3. RapidFix UV Liquid Plastic Adhesive

The RapidFix UV liquid plastic adhesive is very similar to the J-B Weld 2120 epoxy reviewed above. However, it only sets when exposed to UV rays. That means you have enough time as needed to position pieces properly. Once exposed to UV rays, it sets in 10 to 20 seconds and dries crystal clear.

The RapidFix UV liquid plastic adhesive forms a high-strength bond between surfaces. It will stop leakages in plastic radiators. Applying this epoxy is not so straightforward because getting UV light to harden it is a hassle. Rapidfix has a UV LED flashlight to give you total control of its set time (sold separately). However, you can use any UV flashlight, preferably a 365-nm UV flashlight. UV light can be dangerous, so you need to protect your eyes with safety goggles before using the UV light.

The RapidFix UV liquid plastic adhesive comes in two 10 ml bottles. Thanks to the multi-layered screw cap system protection of the containers that prevent evaporation, their shelf life is 24 months. Be informed that this product can only be used for repairs where UV light can pass through the adhesive.

Benefits

  • It only sets when exposed to UV light, which gives enough time to position it well properly.
  • It doesn’t require any mixing. Just apply and expose to UV light for it to harden.
  • This adhesive fills up cracks, gaps, and holes.

Drawbacks

  • You need a UV LED flashlight to activate its bonding process.
  • It only works for repairs where UV light can pass through it.
CHECK PRICE ON AMAZON

4. Permatex 84145 Permapoxy Black Plastic Weld

The Permatex 84145 permapoxy black plastic welder is a powerful epoxy that won’t require any form of mixing or additional work before use. This epoxy comes in a 0.84 fl oz dual syringe cartridge that dispenses in a 1:1 mix ratio. However, to avoid uneven dispense, be careful with how you squeeze the cartridge.

The Permatex 84145 permapoxy black plastic welder can bond plastic and aluminum radiators. It forms a permanent bond with a strength of up to 3500 PSI, making it perfect for repairing radiator leaks. However, it has a strong odor, so use it only in a well-ventilated area. Furthermore, its black color makes it useful for other repairs on your car, be it for your trim or bumper.

The Permatex 84145 permapoxy black plastic welder stands up to the elements, high humidity, and temperature variations. Its set time and curing time are 5 minutes and 10 minutes. The set time is quite fast, however, 5 minutes is enough to apply it properly on the surface you want to repair.

Be informed that the Permatex 84145 permapoxy black plastic welder will not bond polyethylene and polypropylene plastics. So, ensure your radiator plastic isn’t made from these polymers. Also, note that it can only fill holes that are 0.125 inches or less.

Benefits

  • It doesn’t require any mixing or additional work to use.
  • This epoxy creates a permanent bond with strength up to 3500 PSI to repair leaks in radiators.
  • Its black color makes it ideal for making repairs in automotive trim, bumper, or clips.
  • It has a fast curing time.

Drawbacks

  • It has a strong odor.
  • It will not bond polyethylene and polypropylene plastics.
CHECK PRICE ON AMAZON

5. Blue Magic 6522KTRI QuikSteel Plastic Tank Repair Kit

Another plastic epoxy kit on our list is the Blue Magic 6522KTRI Quiksteel plastic tank repair kit. This kit comes with everything you need to repair large leaks in plastic radiators. It includes a 2 oz epoxy, saddle soap, alcohol swab pad, screen, and sandpaper. The epoxy has a bonding strength of 5,950 PSI, which is more than enough to stop any leakage in a plastic radiator. Note that the recommended mixing ratio to get the high-strength bond is 1:1.

The epoxy in this Blue Magic 6522KTRI Quiksteel plastic tank repair kit comes in a 2fl oz container. It has a set time of 5 minutes and a curing time of 1 hour. You will know it has fully cured when an off-white color appears. Also, this epoxy has high-temperature resistance and is waterproof for underwater use. However, be careful when using it because it is known to cause eye irritation. So, always put on safety goggles and gloves whenever you want to use the epoxy.

One downside to the Blue Magic 6522KTRI Quiksteel plastic tank is not suitable for plastic that flexes because it will break or completely shatter if the plastic flexes.

Benefits

  • It forms a bond with a strength of 5,950 PSI.
  • It comes with everything you need to repair plastic radiators.
  • The set time of the epoxy is about 5 minutes, and it cures in one hour.

Drawbacks

  • It causes eye irritation.
  • It is not suitable for plastic that flexes.
CHECK PRICE ON AMAZON

6. K Tool International KTI90002 Q Bond Adhesive Kit

The K Tool International KTI90002 Q bond adhesive kit is different from all the kits we have reviewed so far. This is because it comes with adhesives for both plastic and metal repairs. The kit packaging includes two 10ml bottles of cyanoacrylate adhesive. Cyanoacrylate adhesive has high-strength and fast-bonding attributes that form an ultra-strong bond that is impact resistant and temperature tolerant up to 356°F.

The kit also includes one black 10ml bottle of plastic reinforcing powder, and one grey 10ml bottle of metal reinforcing powder. The plastic reinforcing powder will repair leaks in any plastic radiator, while the metal reinforcing powder works for metals and grey plastic radiators.

The K Tool International KTI90002 Q bond adhesive kit application process involves the reinforcing powder being used as a foundation, then immersed with the adhesive to initiate a chemical reaction, resulting in a repaired surface. It takes 10 to 15 seconds after application for the adhesive to harden. Ensure you wear gloves and eye goggles before working on your radiator because the chemical reaction gives off horrible fumes.

Benefits

  • The kit comes with adhesives for both plastic and metal radiator repairs.
  • The adhesive coupled with the reinforcing powder makes a bond that is impact resistant and temperature tolerant up to 356°F.
  • It is very affordable.

Drawbacks

  • The chemical reaction of the adhesive and reinforcer powder gives off horrible fumes.
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7. Gorilla 433010 Weld Steel Bond 2-Part Epoxy

The Gorilla 433010 weld steel bond 2-part epoxy creates a permanent bond strong enough to repair leaks, holes, and cracks in plastic radiators. It consists of a hardener (14.5ml) and a resin (14.5ml), that when mixed, forms a bond with a tensile strength of 4250 PSI. The bond is waterproof and has a temperature resistance that ranges from -40°F to 300°F.

This epoxy works on a variety of plastic surfaces, including ABS and Polyester. On polypropylene and polyethylene, however, it may not be as effective. It takes 10 minutes to set and 24 hours to cure completely. You’ll know it has completely cured when it turns dark grey.

The Gorilla 433010 weld steel bond 2-part epoxy is harmful to the skin, so ensure you put on protective gears before using it. Also, it has a horrible smell.

Benefits

  • It creates a permanent bond with a tensile strength of 4250 PSI.
  • The bond it creates is waterproof and can withstand temperatures ranging from -40°F to 300°F.
  • This epoxy has a fast set time.

Drawbacks

  • It doesn’t work on polypropylene and polyethylene plastic.
  • It is harmful to the skin and has a horrible smell.
CHECK PRICE ON AMAZON

8. Versachem 90214 Plastic Tank and Radiator Repair Kit

The Versachem 90214 plastic tank and radiator repair kit comes with an epoxy that makes permanent repairs to plastic and metal radiators and tanks (both fuel and diesel tanks). It repairs leaks, crack, and holes of up to ½” diameter. The kit contains a 30g epoxy pouch (resin & hardener), fiber cloth, applicator, and sandpaper. It is also very cheap.

With this kit, there is no welding or draining of components involved in making repairs to tanks or radiators. Just mix the hardener and resin evenly, then pour the mixture into the radiator or tank and it will make repairs in under 20 minutes. However, note that when mixed, this epoxy gives off tremendous heat and sets fast. Due to this, always ensure you have the tank or radiator you want to repair ready before mixing. Curing time is also fast.

The epoxy in this Versachem 90214 plastic tank and radiator repair kit can withstand high temperatures ranging from 40°F to 200°F. The bond it creates has a tensile strength of 1500 PSI. Be informed that this epoxy works on most plastic and metal, but it won’t work on polyethylene or polypropylene plastics.

Benefits

  • It repairs leaks, crack, and holes of up to ½” diameter in plastic and metal radiators and tanks.
  • The bond it creates has a tensile strength of 1500 PSI and can withstand high temperatures ranging from 40°F to 200°F.
  • It is cheap and offers value for money.

Drawbacks

  • It sets fast, which won’t give you enough time to position the epoxy well.

9. Permatex 84109 PermaPoxy 4 Minute Multi-Metal Epoxy

Permatex makes our list again, this time with their 84109 permapoxy 4-minute multi-metal epoxy. It features a two-part adhesive in a 0.84 oz dual-syringe that dispenses evenly for easy application. This epoxy is specifically designed for repairing leaks, cracks, and holes in metal radiators. It creates a permanent bond with a tensile strength of up to 4500 PSI. This makes the epoxy suitable for repairing any radiator made from metals like aluminum, brass, chrome, copper, iron, stainless steel, and steel.

Thanks to its set time of four minutes, you will have enough time to position it properly in the radiator. It cures in 24 hours to a dark grey color. This epoxy has a wide range of temperature tolerance. It can withstand a low temperature of -60°F and a high temperature of up to 300°F. And it is resistant to water and solvents.

Benefits

  • It repairs leaks, cracks, and holes in metal radiators.
  • It creates a permanent bond with a tensile strength of up to 4500 PSI.
  • Its dual-syringe container makes application easy.

Drawbacks

  • None.

10. J-B Weld 8237 Plastic Repair Epoxy

To round up this review is the hand mixable two-part J-B Weld 8237 plastic repair epoxy. This epoxy repairs leaks and cracks in plastic radiators by forming a permanent bond with the plastic. The bond it creates has a tensile strength of 600PSI and can withstand continuous temperatures up to 250°F and intermittent temperatures up to 300°F when fully cured. It takes this epoxy 25 minutes to set and 3 hours to cure. You’ll know it has fully cured when its color turns off white.

The J-B Weld 8237 plastic repair epoxy comes packaged in a 2fl oz container. It cost less than $10. Like most of the plastic epoxy on our list, it doesn’t adhere to polyethylene or polypropylene plastics. Applying it is easy. Just take out the portion you want to use from both parts of the epoxy, knead, and apply on the part of the radiator that leaks. However, you may experience some mess because it is sticky.

Note that it will only work for cracks and holes not larger than ⅛” diameter. If the hole in your radiator is larger than ⅛”, then consider another plastic epoxy.

Benefits

  • It creates a bond with 600PSI tensile strength and withstands 250°F continuous and 300°F intermittent temperatures.
  • It has a set time of 25 minutes.
  • The epoxy is affordable.

Drawbacks

  • The epoxy is sticky, which causes a mess when kneading.

Final Thoughts

Purchasing an epoxy for your plastic radiator repair will not only save you money but will also help you maintain and keep your radiator in good shape for many years. Ten epoxies have been discussed in this article.

These epoxies are from different brands but will repair radiators with holes, leaks, or fractures in minutes. So, all that’s left for you to do is to choose the right epoxy according to your automobile engine and radiator features. Good Luck.

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