Crossflow radiators and coolant reservoirs prevented overheating. No change to the oil pump nor coolant pump circuits was needed. Molten salt fuels have nuclear fuel dissolved directly in the molten salt coolant. Liquid carbon dioxide coolant was also replenished. It then joins the third flow path from the chamber coolant valve. Disadvantages of liquid cooling include complexity and the potential for a coolant leak. Liquid sodium was a secondary coolant. Liquid metal coolant (NaK) surrounds each fuel element. Proper engine coolant and a pressurized coolant system obviate the shortcomings of water. Water was the original coolant for internal combustion engines. Tesla uses proprietary technology for packaging and cooling the cells in packs with liquid coolant. The reactor outlet coolant is supercritical water. The reactor is cooled using the natural convection of another molten salt coolant. The cylinder sleeve is in contact with the engine coolant, hence the "wet"-sleeve. This high heat capacity makes water a good heat storage medium (coolant) and heat shield.