A great deal of different types of water lines can be used with success, but there are several guidelines to follow when selecting the lines. Be sure to use hoses or lines that are rated to at least as hot as the engine coolant temps will ever get, which can be as high as 250°F (121°C) or higher in some cases. The lines or hoses should be designed to be compatible with water and antifreeze, and most are. AN-style (37° fl are) fi ttings are recommended for easy installation and leak-free systems, and a variety of adapters to Garrett® water ports are available from many distributors. Either hard steel lines or fl exible lines can be used, but care must be taken to ensure hard lines are not subject to damaging vibration. As the engine is running there will be normal engine vibration, but there will also be movement of the lines as the engine rotates on its mounts during high torque output. Hard lines without some sort of fl exible section between their ends can be cracked or bent from engine rotation or fatigued from normal engine vibration, depending on how they are routed. Cracked hard lines will lead to coolant leaks, so extra consideration for motion and vibration should be taken when using hard lines