Radiator caps & weld-on flanges

Radiator caps and weld-on flanges are used in cooling systems where secure sealing, correct pressure control and a solution that matches the specific setup are needed. This applies to standard road cars, modified cars, motorsport vehicles and custom projects, where the radiator, expansion tank or another cooling component needs to be built or adapted. In this category you will find both radiator caps with and without weld-on flanges, as well as separate weld-on flanges for projects where you want to choose the final combination yourself.

A radiator cap is not just a cap. It is an important part of the system’s pressure control and affects how the cooling system works under load. A correct cap helps maintain the desired pressure in the system, and this has an impact on reliability, temperature control and how the coolant is handled when the engine gets hot. That is why it is important to choose a solution that matches both the pressure requirements, the intended use and the way the rest of the cooling system is built.

Radiator caps without a weld-on flange are typically used as a replacement or upgrade where a suitable filler neck or mounting solution already exists. It is a simple solution for systems where only the cap itself is needed and where the rest of the setup is already in place. This can be relevant for service, replacement of a worn cap or upgrading to a different pressure rating.

Radiator caps with a weld-on flange are suitable for custom-built solutions where you want a complete setup with flange and cap that can be welded directly onto the radiator, expansion tank or another reservoir. This provides a practical and simple setup where the components fit together from the start. It is especially relevant in motorsport, engine swaps, aluminium tanks and other custom projects where standard solutions do not always fit.

Separate weld-on flanges are used when you want to build your own solution and combine the flange with a separate radiator cap. This gives greater freedom in projects where a specific type of cap, a specific pressure rating or a specific location on the tank or radiator is required. A separate weld-on flange is therefore often a good choice for tailored cooling systems where fitment and layout need to be matched precisely to the car or the project.