Repair Cracked Plastic Radiator

If your car radiator has a small leak, you may be wondering if it is possible to repair a plastic radiator and fix a radiator leak. After all, there is high-pressure, high-temperature coolant in the radiator tank. You may ask yourself, "How can a radiator epoxy adhesive possibly hold up under those conditions?" The answer is that it probably can't. It may fix the radiator leak temporarily, but over time, the radiator adhesive will, more than likely, come off.

If you take your car to a radiator repair shop to repair a leaking radiator, you will often find that they will repair metal radiator tanks but NOT repair plastic radiator tanks. Instead, the radiator repair shop will probably try to sell you a replacement radiator. The replacement radiator cost can be very high compared to just repairing something so minor and easily repairable.

Radiator tank repairs are not difficult at all. Just keep in mind a few things when you are repairing a cracked plastic radiator tank. First, the repair has to withstand high operating temperatures (200°F or 94°C and up).

Second, the repair has to contain hot, pressurized coolant, making it immediately obvious when your weld is less-than-perfect. Because of the harsh operating conditions, the radiator tanks are made from glass-reinforced nylon, a plastic that features a high-softening point. The high-softening-point nylon plastic is what helps the plastic radiator tank withstand the pressure and temperatures involved.

Adhesives don't stand a chance in such an environment. There's no way an adhesive bond can hold on over the long run at such temperatures with high-pressure water behind it.

The only true way to patch a plastic radiator tank is with a true fusion weld. The Radiator Repair Kit enables you to melt pure nylon fill material directly into the base material, creating a seamless, strong repair that will last for the long haul.

Creating a durable weld repair is not as easy on the radiator as it is on other plastic parts because of the high melting point of the nylon and the harsh operating conditions. However, by following the simple step-by-step procedure we have outlined here, you will be making quality repairs in no time.

With this kit, you get a heavy duty heating element, a tip that makes repairing a leaking radiator easy, and 15 feet (4.6 m) of nylon welding rod (the same material from which car radiators are made).

Always wear proper safety gear while working!

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Products Used:

Note: This is a list of the Polyvance products that can be used to make this repair. This list does not include sanders, grinders, or other common tools you will need. If you have any questions, please don't hesitate to call technical support at 800-633-3047.

• 5212 Plastic Radiator Tank Repair Kit
• 6121-T Tear Drop Cutter Bit
• View our nylon rods here.

Video Notes:

• English Closed Captions have been provided for this video. Click on the CC button to turn them on or off.
• The length of this video is in no way representative of the actual time required to perform a complete repair and therefore should not be used for estimating purposes.

English Transcript:

Polyvance's Radiator Repair Kit allows you to fix a leaking plastic radiator tank. To show how confident we are with our Radiator Repair Kit, we drilled a hole into a perfectly good radiator. Not only did we drill a hole in the radiator, but we cracked the tank with a chisel.

Before you start repairing, you will need to drain the radiator until the coolant level is below the hole. Create a v-groove along the crack line about two-thirds of the way through the thickness of the plastic. You can either melt a v-groove, or you can use a rotary tool and grind a v-groove like we did here.

Plastic radiator tanks are made of nylon, which has a very high melting point of about 425 degrees Fahrenheit. While it is not required, the repair will go faster if you pre-soften the plastic with a heat gun.

Melt the nylon rod into the v-groove with the plastic welder. The rod should come out melted and a little bit brown, but not discolored too badly. While the melted plastic is still hot, use the tip of the welder to stir together the new plastic and the radiator plastic. Keep mixing until the plastic is all one color. You need a good mix of the existing plastic and the new plastic to achieve maximum strength.

When the repair is complete, allow time for the plastic to cool and re-solidify. The car was started and allowed to run for forty-five minutes. Forty-five minutes allowed plenty of time for the engine to reach operating temperature. As you can see, there is no leaking whatsoever.