Holts Radweld

Holts Radweld is a DIY repair product that is designed to seal small leaks in the cooling system. Tested in our state of the art lab and in real-world conditions, Radweld is proven to seal small holes, cracks and fissures from within the system, providing a permanent repair for a fraction of the price of replacement parts.

Steam from your radiator and an overheating engine doesn’t have to ruin your day or cost a fortune to repair. With its advanced formula, Holts Radweld will target leaks in your car’s cooling system, safely sealing gaps and holes without causing any damage or clogging within the engine.

  • Stops leaks in radiators and hoses
  • Seals in minutes with no clogging or damaging effects
  • Prevents future leaks
  • Simply pour for a repair in minutes

Features and Benefits

Radweld is suitable for all cars and mixes with all types of coolant/antifreeze already in the cooling system. You don’t need any special preparation to use Radweld and there’s no need to drain or flush the cooling system.

Radweld also prevents future leaks to help keep your car on the road for longer. By treating areas of corrosion and pitting at the source, the product effectively extends the life of your coolant/antifreeze and individual components within the cooling system, which helps to prevent future leaks while maintaining the efficacy of engine cooling for longer.

Holts develop products for you right here in the UK, based on the ever-changing needs of the car market, so they’re easy to use.

How it Works

Quick and easy to use, Radweld gets to work instantly, circulating through the cooling system to form a permanent and long-lasting repair. Never has it been easier or more convenient to treat and fix problems in your car’s cooling system.

Simply pour and fix, it couldn’t be easier. Radweld then works its way through the system to target radiator leaks without damaging or clogging the system.

No matter where the leak or problem area is within your car’s cooling system, Radweld’s specialist formula will seek out holes, cracks and areas of abrasion, bonding to the material to form a permanent repair. The product is applied directly to the coolant/antifreeze reservoir without the need to flush the system, for complete convenience.

Take a look at our instructional video below to see Holts Radweld in action

What the experts say…

Jonathan Fry

“A car arrived in the workshop on a Saturday morning with a leaking radiator. After the engine had cooled down I introduced Radweld into the cooling system and ran the engine for half an hour during which time the leak stopped. The customer reported back the following week to say it had remained leak free. Happy customer!”

Jonathan Fry, Owner of Jonathan Fry Automotive

Frequently Asked Questions


Radweld is available in stores across the UK, including large DIY shops and specialist retailers such as motor factors. Where to Buy lists stockists and retailers in your area.

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No. Radweld has been developed and tested in our UK lab to repair leaks in radiators without clogging the channels, and causes no damage to your radiator.

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Add Radweld directly into the expansion tank. Make sure the car is cool before you unscrew the cap and top up with coolant antifreeze following the instructions in the vehicle owner's manual.

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Yes. Radweld's pour and go formula is ideal for a fast repair to your car's radiator.

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We advise that you check the detail of the warranty with the provider.

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