A cooling system flushing tool is a device that enables a cooling system or heater core to be cleaned without taking the assembly apart or, in some cases, without using a caustic solutions.

The cooling system flushing tool shown here connects to a 13mm (1/2"), 16mm (5/8"), or 19mm (3/4") hose and uses water supplied by a standard garden hose. Other flushing systems come with complete with a canister of flushing solution, for removing stubborn residues and particulates, and a hose for connecting the canister to the hose gun.