Labyrinth seal for rear of internal combustion engine

An internal combustion engine comprising:

• an engine block rotatably supporting a crankshaft for rotation about a crank axis;
• wherein the engine block includes a rear end wall defining a rear crankcase opening, with the crankshaft extending through the rear crankcase opening;
• a rear main seal positioned within the rear crankcase opening and disposed annularly about a circumference of the crankshaft for sealing the rear crankcase opening between the engine block and the crankshaft;
• a torque transmitting disc mounted to a rearward end of the crankshaft for rotation with the crankshaft about the crank axis;
• wherein the rear end wall of the engine block and a forward facing end surface of the torque transmitting disc are formed to define a labyrinth seal therebetween, with the labyrinth seal disposed radially outward of the rear main seal relative to the crank axis for blocking debris from contacting the rear main seal from an external side of the rear main seal;
• wherein the labyrinth seal includes an annular block projection defined by the rear end wall, wherein the annular block projection is disposed radially about the crank axis and extends from the rear end wall a first distance in a rearward direction along the crank axis;
• wherein the labyrinth seal includes an annular disc projection defined by the torque transmitting disc, wherein the annular disc projection is disposed radially about the crank axis and extends from the forward facing end surface a second distance in a forward direction along the crank axis;
• and
• wherein the annular block projection and the annular disc projection overlap each other axially along the crank axis.