Device (10; 110; 210) for indicating heating in a mechanical system liable to experience contact heating in operation, for example a rolling bearing, a plane bearing or a ball joint, the indicating device (10; 110; 210) comprising at least: - a body (20; 120; 220) containing a thermally initiable charge (40 140; 240) that generates a combustion gas, ignition of the charge (40; 140; 240) being able to be initiated under the effect of a predetermined addition of heat, from a heating zone (Z24; Z124; Z224) of the body (20; 120; 220) towards the charge (40;; 140; 240), or under the action of an ignition command, - a reservoir (60; 160; 260) containing a fluid, and means (36, 68; 136, 168; 228, 268) for delivering pressurized fluid out of the reservoir through the action, either direct or via an intermediate member (72; 172; 272) able to move inside the reservoir, of the combustion gases, - means (30, 32, 34; 130, 132, 134; 230, 232, 234) for attaching the indicating device (10; 110; 210) to a mechanical system, the attachment means being designed to place the reservoir (60; 160) in fluidic communication with the mechanical system and to position the body (20; 120; 224) against the mechanical system in the region of the heating zone (Z24; Z124; Z224), characterized in that: - the indicating device (10; 110; 210) comprises at least one element (27; 152; F) visually indicating the combustion of the charge (40; 140; 240), the visual-indication element being visible at an exterior peripheral zone (Z50; Z150; Z250) of the indicating device after combustion of the charge, and - the attachment means comprise at least one injection bushing (30; 130; 230) provided with an external screw thread (32; 132; 232) coated with a thread locking adhesive film (34; 134; 234) to prevent loosening. - a body (20; 120; 220) containing a thermally initiable charge (40 140; 240) that generates a combustion gas, ignition of the charge (40; 140; 240) being able to be initiated under the effect of a predetermined addition of heat, from a heating zone (Z24; Z124; Z224) of the body (20; 120; 220) towards the charge (40;; 140; 240), or under the action of an ignition command, - a reservoir (60; 160; 260) containing a fluid, and means (36, 68; 136, 168; 228, 268) for delivering pressurized fluid out of the reservoir through the action, either direct or via an intermediate member (72; 172; 272) able to move inside the reservoir, of the combustion gases, - means (30, 32, 34; 130, 132, 134; 230, 232, 234) for attaching the indicating device (10; 110; 210) to a mechanical system, the attachment means being designed to place the reservoir (60; 160) in fluidic communication with the mechanical system and to position the body (20; 120; 224) against the mechanical system in the region of the heating zone (Z24; Z124; Z224), - the indicating device (10; 110; 210) comprises at least one element (27; 152; F) visually indicating the combustion of the charge (40; 140; 240), the visual-indication element being visible at an exterior peripheral zone (Z50; Z150; Z250) of the indicating device after combustion of the charge, and - the attachment means comprise at least one injection bushing (30; 130; 230) provided with an external screw thread (32; 132; 232) coated with a thread locking adhesive film (34; 134; 234) to prevent loosening.