Abstract: A radiator core cleaning device for manually removing rust, corrosion, mineral deposits and other compounds or elements from the cores of heat exchangers such as motor cooling radiators used in automobiles, trucks, buses, other like vehicles and other various type motors employing radiator cooling devices that comprise cores of tubular passageways. The cleaning device comprises a rigid, elongated, L-shaped tubular shaft pierced throughout its length and through its diametric center by a semi-flexible shaft that through a manually applied reciprocating motion moves out of and into said aforementioned rigid, elongated, L-shaped tubular shaft into and out of the tubules of a radiator core upon which the device is being used to physically remove build-ups of rust, corrosion, mineral deposits and other compounds or elements from said core.