Joint structure for an blow-by gas passage

An internal combustion engine and crankcase ventilating system therefore comprising an induction system for collecting atmospheric air and delivering the collected air to at least one combustion chamber of said engine, a crankcase ventilating system for collecting and exhausting blow by gasses from said engine and returning them to said combustion chamber through said induction system for reducing undesirable emissions to the atmosphere, said crankcase ventilating system communicating with said induction system through a fitting having a double wall construction comprised of an inner tube received in an outer tube, aid outer tube being fixed at one end thereof to said induction system and receiving a flexible conduit at the other end thereof, said flexible conduit communicating at the other end thereof to receive blow by gasses from said engine, the outer wall of said inner tube being circumferentially spaced from the inner wall of said outer tube at both ends thereof for heat insulation of the blow by gasses.