A thermal engine for an automotive vehicle, including at least one cylinder block including a first inner circuit for circulating a cooling liquid, of the type in which the first inner circuit includes an outer supply duct including an inlet opening into a reception chamber for a rotor of the engine water pump formed in the block. The chamber includes in its intermediate portion a supply opening having a level located above the level of the inlet opening of the inner supply duct of the first inner circuit. An additional degassing duct connects the upper portion of the reception chamber or water pump volute with an element of the engine cooling circuit.