When your radiator breaks down, that’s more than just a simple inconvenience.

You must act quickly if you’re dealing with leaks and want to prevent further damage.

And the fastest and easiest way to fix a broken plastic radiator is with the help of an adhesive.

In this article, I’ll talk about the best plastic glue for fixing plastic radiator damage.

Minor cracks or a single broken pipe are bad enough to diminish your radiator’s performance and cause moisture damage.

Since ignoring these issues isn’t an option, you’re thus left with two choices— repairing your radiator or buying a new one.

Luckily, a long-lasting, high-quality fix is well within reach if you know what to look for.

Keep reading for more plastic radiator glues! You won’t want to miss out on these!

Suitable Glues for Plastic Radiator Repair

A material-compatible adhesive will help seal a damaged plastic radiator. However, you must account for more than adhesion power and bond strength.

Since we’re talking about radiators, the adhesive you choose must also have decent resistance to water, pressure, and heat.

Keeping all this into account, here are the best glue options.

Alternatively, you should also check out our guide on glues to fix fridge plastic.

Epoxy Glue

Epoxy glue is excellent for small repairs as well as larger-scale projects. Most epoxies are compatible with virtually any material, including very smooth and hard plastics and metals.

Other major advantages include extreme water resistance and high tensile strength.

Epoxies form very powerful bonds that are unlikely to crack or come undone when exposed to high pressure or humidity.

Epoxies are also easy to use for such repairs because they have minimal, almost undetectable shrinkage as they cure.

You see what you get, and the adhesive is unlikely to peel away and leave uncovered areas.

This is very important when sealing cracks and punctures, as you might end up with exposed areas when the adhesive cures and shrinks.

Most epoxies can also withstand pretty high temperatures once fully cured. Anything under 345°F should be safe.

Beyond this point, regular epoxies will start to lose their strength.

However, heat-resistant glues and epoxies are formulated to withstand temperatures as high as 600°F without breaking down.

Silicone Sealant

Silicone sealant could make another suitable choice for fixing plastic radiators.

This glue has proper adherence to a wide list of materials, including smooth ones like metal and plastic.

Its excellent moisture resistance is also commonly used for caulking cracks.

However, it’s less adhesive than epoxy and might require a primer.

Silicone has low thermal conductivity, which makes it great for insulating. It can withstand pretty high temperatures on its own.

You can also find high-temperature silicone sealants specially formulated to resist temperatures up to 500°F when fully cured.

All this being said, silicone sealant is less durable than epoxy glue. That’s because it doesn’t always have the highest tension resistance.

The tensile strength can vary wildly between products and brands, so you’ll have to look for silicone sealants marketed as heavy-duty or high PSI.

Shrinking doesn’t differ much between silicone sealants and epoxies. Both adhesives shrink by around 1-5% on average when curing, which isn’t enough to pose issues.

It’s worth mentioning that there are some curing differences between the two types of glue.

Epoxies might take up to 72 hours to cure, while silicone sealants usually take 24 hours.

Best 4 Glues for Plastic Radiators

Below are my recommendations for the best glue for plastic radiator repair.

1. J-B Weld 2120 Radiator and Plastic Repair Kit

This J-B Weld 2120 Radiator and Plastic Repair Kit has everything you need for permanent, professional-grade radiator repairs.

You get a high-strength, steel-reinforced epoxy putty, an applicator, sandpaper, and fiberglass cloth.

With these tools on hand, you can not only work on radiators but also on applications like water tanks, storage tanks, washer fluid tanks, and more!

This adhesive is compatible with multiple plastics, including PVC, composites, aluminum, copper-brass, and other metals.

No matter the type of radiator material, this J-B Weld epoxy got you covered!

You can use this putty to seal and fill in cracks up to 4” long. Fixing holes up to 3/8” diameter is equally easy with this amazing product on hand.

Apart from being highly versatile and compatible with many materials, this adhesive is also very easy to mix and apply.

It has a very short setting time of just 5 minutes and cures completely in as little as 4 hours.

Thanks to its steel-reinforced formula, this glue bonds extremely strong and creates tight, unbreakable bonds.

Once fully cured, this glue has an insane tensile strength of 3100 PSI and high chemical and temperature resistance up to 250°F.

2. Versachem 90214 Plastic Tank and Radiator Repair Kit

When you need a quick, permanent fix, you can always count on the Versachem 90214 Plastic Tank and Radiator Repair Kit.

Once you mix the two epoxy parts, you’ll get a liquid rubber material that’s easy to apply and spread.

And thanks to the short setting time, you’ll be done in just 20 minutes.

This adhesive contains ultra-high molecular weight polyethylene resin for increased resistance and strength.

Once fully cured, the epoxy bond remains fixed and highly resistant to gasoline, diesel, kerosene, and other solvents.

It can also withstand temperatures ranging between 40-200°F.

You can use this adhesive for various applications, including repairing pinholes, hairline cracks, rust-outs, and holes up to 1/2” diameter.

Its high solvent resistance makes it a great candidate for gasoline and diesel fuel tank repairs.

This adhesive works on multiple metals and plastic materials; however, it is not suitable for all types of plastic.

It’s also a great glue for HDPE.

On the plus side, this glue requires no draining or welding. The kit also includes everything you need, including the epoxy parts, an application brush, sandpaper, and fiberglass cloth.

3. Super Glue Pro Seal N62020 Instant Gas Tank and Radiator Repair

The Super Glue Pro Seal N62020 Instant Gas Tank and Radiator Repair is a great combination between epoxy, putty, and cyanoacrylate glue.

This product is easy to use because you can mix it by hand. It also bonds to surfaces extremely quickly, so you don’t have to wait for a long time.

This epoxy glue is a great choice if you want instant radiator or gas tank repairs.

You can use it to seal cracks, broken pipes, split seams, and so much more!

This glue is compatible with virtually all materials and surfaces. It even adheres well to wet surfaces.

There’s no draining or tank removal required. It doesn’t matter what you have to fix. You can do so on the spot.

Once fully cured, the final bond is as hard as steel. This product is a great choice when you need a quick yet powerful fix.

It also works as a glue for miniatures, among many other uses.

4. Blue Magic 6022K Quiksteel Metal Tank Repair Kit

The Blue Magic 6022K QuikSteel Metal Tank Repair Kit includes all the tools you need for quick and effective repairs.

For a highly affordable price, you get an epoxy putty sealant, a wire brush, a sandpaper pack, a foam injector, and a drill bit.

You can use this kit for all sorts of radiator repairs and metal tank repairs.

There isn’t any draining required, as this epoxy sets up even in high humidity conditions.

Even better, this epoxy is very easy to use. It has excellent adherence on smooth surfaces and sets in just 5 minutes. You can hand-mix it like putty.

After just one hour, the bond is fully cured and as strong as steel.

The cured adhesive is completely impenetrable, unbreakable, and highly resistant to water, gasoline, oil, diesel fuel, and other solvents.

It can also be sanded and painted.

Because this adhesive is steel-reinforced, it has an incredible tensile strength of 5950 PSI. That’s higher than any other glue on this list.

This glue is also highly resistant to temperatures ranging from -90°F to 500°F.

How To Spot Damage in Plastic Radiators

Radiator damage can occur in any of the radiator components.

Whether we’re talking about the outlet or inlet pipes, tanks, pressure caps, or core assembles, each part of the radiator should work smoothly.

You need to do regular checks to make sure that nothing is broken.

As soon as you notice cracks or other types of damage, even if minor, you should seal the broken components to prevent further problems.

Even if you don’t notice any negative effects, it’s best to be proactive.

However, you must first know what to look for and how to troubleshoot such problems. Here are some useful tips:

• Check all the pipes and fittings and see whether they have cracks or holes. If they do, don’t use them until you have repaired them. Your radiator system may be leaking water, and you’ll need to address this problem sooner rather than later.
• Is the problem localized or is it a general issue? If only certain unit parts are cracked and damaged, you only need to repair those instead of replacing the entire radiator. It’ll be cheaper this way.
• Try to spot the signs of water leaks – If there are wet spots on the floor, your radiator is leaking.

If you want your radiator to work at all times, check it regularly for any damage.

Fortunately, repairing your radiator isn’t difficult at all. You have to have a good adhesive on hand.

Before any of that, though, you need to eliminate any heat insulation. Then, apply the glue and don’t touch anything until it dries completely.

You should clean the area with denatured alcohol beforehand, though.

Use a putty knife to remove all the old and loose parts, clean everything, and then glue everything together.

Use a heat source to improve the setting time!

What’s The Best Glue for Fixing a Cracked Radiator?

I recommend a two-part epoxy because it forms a thick cream when mixed thoroughly.

You should apply the glue to both parts of the crack in the radiator but be careful, so the glue doesn’t overlap on both sides when it dries.

You should cover the metal clips because they will rust in time if you leave them exposed.

You can use an electric heater to speed up the curing process. However, if you don’t clamp the materials, using heat may lead to cracks in the joints.

That’s about it when using epoxy to repair a cracked radiator.

Silicone sealant is also good for this. It’ll take a lot of time for the sealant to dry.

Initially, it’s not waterproof, and only after it cures does it become waterproof.

You may also have to offer maintenance to the rubber seals periodically so they don’t deteriorate in time.

You can follow the step-by-step guide below to repair your cracked radiator using epoxy:

• Clean the radiator using water and a scrubbing brush. Remove all the dirt and rust stains, then rinse everything with water
• Use a damp cloth to remove the excess water
• Apply epoxy in small sections of the radiator and let the adhesive dry for 15 minutes before applying another epoxy coat. You need to apply the adhesive around the radiator’s exterior until everything is covered. Don’t scratch the plastic when you push the bubbles, though. You need to wait 24 hours before applying the final epoxy layer.
• I recommend applying vinyl sheeting on the top of the radiator to prevent wear and tear accidents.

It’s really easy to repair your plastic radiator with epoxy, as you can see!

Wrap-up

Glues were made to help us repair stuff. In this case, epoxy glue can help you repair your plastic radiator quickly and efficiently.

J-B Weld 2120 Radiator and Plastic Repair Kit is my number one pick for this list, a strong, durable, quick-setting, and versatile epoxy adhesive!

If you have any questions, leave them below, and I’ll answer them as soon as possible!