An engine assembly includes an engine block, a cylinder head coupled to the engine block and first and second lubrication systems. The combustion air conduit is configured to direct the majority of the combustion air to the first air heater, and the flue gas conduit is configured to direct the majority of the flue gas from the boiler to the second air heater. The carriage supports a mast containing a compression coil spring within. When actuated, a vacuum switch pulls a flapper valve located in the diversion assembly that redirects engine exhaust.