A torque converter is a type of fluid coupling which is used to transfer rotating power from a prime mover, such as an internal combustion engine, to a rotating driven load. The torque converter normally takes the place of a mechanical clutch in a vehicle with an automatic transmission.
Torque converters are not designed to be reused. The fluid inside a torque converter is constantly being circulated and is under a lot of pressure. Over time, the fluid breaks down and starts to leak. The seals and gaskets in a torque converter can also wear out, leading to leaks.
If a torque converter is removed from a transmission, it should be replaced with a new one. Reusing a torque converter is not recommended and could lead to transmission problems.