The invention relates to a heating device for motor vehicles with an internal combustion engine and a coolant circuit. The heating device (1) comprises a heat-generation compartment (2) with a cooling jacket (6) around which a coolant flows, and a rotor (13) mounted on a drive shaft (9). The cooling jacket (6) is part of a cooling chamber (3) that comprises a coolant inlet (4) and a coolant outlet (5). A pump wheel (17) is disposed in the cooling compartment (3), is driven by the drive shaft (9) and circulates the coolant.