Abstract: A fuel preheating system for an internal combustion engine wherein a preheater includes a body member having defined therein a pair of serially connected, generally parallel bores defining a flow passages through which a flow of fuel may be passed for heating thereof by elongated electric heaters extending within the passages and including a heating element encompassed by helical coils of a heat exchange structure. At least some of the coils of the heat exchange structure define plural tortuous flow paths extending generally axially of the heater.

Abstract: A fuel preheating apparatus and method for use in conjunction with an internal combustion engine including a preheater wherein a flow of fuel to be heated is maintained in juxtaposition to a pair of selectively operable heat sources, one of which is a flow of engine coolant. An additional heat source is provided to heat the flow of engine coolant through the preheater to thereby provide engine block warming during extended periods of engine shutdown.

Abstract: A heat sealing or heat welding apparatus for sealing lapped joints in laid up roof structures having an interchangeable drive for driving either or both of a pair of laterally spaced drive wheels and in which a heating element is selectively movable to plural operative positions including positions in alignment with the drive wheels whereby drive wheels perform the dual function of a traction drive and a pressure roll, and the drive wheels are able to traverse a path of travel coincident with that of the heating element during heat sealing of such lapped joints by the apparatus. The interchangeable drive and multiple operative positions of the heating element permit the apparatus to move forwardly for traverse of the lapped joint in either of the opposite directions of travel therealong.