A flow deflector suitable for a heat exchanger of the type consisting of at least one core made up of tubes forming a bundle arranged inside a shell and at least one baffle, such that said deflector comprises: - a main body extending along an X-X direction, - a plurality of at least three fixing elongations (1.2, 1.3) protruding transversely with respect to the X-X direction of the main body defining a main plane containing the X-X direction, wherein such fixing elongations (1.2, 1.3) are such that: ∘ they are formed by two groups, a first group of fixing elongations (1.2) and a second group of fixing elongations (1.3) such that the first group of fixing elongations (1.2) is distributed along the X-X direction and located on one side of the main plane; and wherein the second group of fixing elongations (1.3) is distributed along the X-X direction in positions different from the positions of the elongations of the first group of fixing elongations (1.2) and located on the opposite side of the main plane, ∘ each of the elongations (1.2, 1.3) is arranged at least in a sector away from the main plane defining a housing such that the set of housings of the elongations (1.2, 1.3) is suitable for housing a sector of baffle (2.2) of the heat exchanger for fixing the flow deflector, - deflecting extensions (1.2.2, 1.3.2, 1.5) suitable for being located in the spaces located between the tubes (2.1) of the core made up of tubes of the heat exchanger and suitable for modifying the coolant flow path. - a main body extending along an X-X direction, - a plurality of at least three fixing elongations (1.2, 1.3) protruding transversely with respect to the X-X direction of the main body defining a main plane containing the X-X direction, wherein such fixing elongations (1.2, 1.3) are such that: ∘ they are formed by two groups, a first group of fixing elongations (1.2) and a second group of fixing elongations (1.3) such that the first group of fixing elongations (1.2) is distributed along the X-X direction and located on one side of the main plane; and wherein the second group of fixing elongations (1.3) is distributed along the X-X direction in positions different from the positions of the elongations of the first group of fixing elongations (1.2) and located on the opposite side of the main plane, ∘ each of the elongations (1.2, 1.3) is arranged at least in a sector away from the main plane defining a housing such that the set of housings of the elongations (1.2, 1.3) is suitable for housing a sector of baffle (2.2) of the heat exchanger for fixing the flow deflector, ∘ they are formed by two groups, a first group of fixing elongations (1.2) and a second group of fixing elongations (1.3) such that the first group of fixing elongations (1.2) is distributed along the X-X direction and located on one side of the main plane; and wherein the second group of fixing elongations (1.3) is distributed along the X-X direction in positions different from the positions of the elongations of the first group of fixing elongations (1.2) and located on the opposite side of the main plane, ∘ each of the elongations (1.2, 1.3) is arranged at least in a sector away from the main plane defining a housing such that the set of housings of the elongations (1.2, 1.3) is suitable for housing a sector of baffle (2.2) of the heat exchanger for fixing the flow deflector, - deflecting extensions (1.2.2, 1.3.2, 1.5) suitable for being located in the spaces located between the tubes (2.1) of the core made up of tubes of the heat exchanger and suitable for modifying the coolant flow path.