Heat exchanger and fabrication process of the latter

The casing (1) section comprises a plastic support component (21). On the side facing the coolant, it is covered by a protective component (22) made of a different plastic. At high temperatures, this is chemically-resistant to water and glycol. The support component has a composite structure, comprising a matrix with embedded reinforcement, especially glass fibers. The protective component plastic contains filler. The protective component is markedly thinner than the casing (1). An independent claim is included for the method of manufacture.