Seal structure in engine body

A seal structure in an engine body, comprising:

• a crankcase which has a crank chamber and which is coupled to a flat lower end face of a cylinder block having a cylinder bore, the crankcase being comprised of first and second case halves having oppositely facing joint surfaces coupled to each other in a plane extending perpendicular to the lower end face of said cylinder block, wherein only one of the joint surfaces of said first and second case halves includes a U-shaped seal groove extending along a peripheral edge of said crank chamber, and wherein enlarged recesses are provided only in said one of the joint surfaces of the first and second case halves and extend laterally from opposite ends of said seal groove to be surrounded by the cylinder block and the first and second case halves;
• a bar-shaped seal member mounted in said seal groove to come into close contact with the other of said joint surfaces of the first and second case halves such that enlarged end portions integrally formed at opposite ends of said bar-shaped seal member are entirely filled in the enlarged recesses;
• and
• a gasket of a sheet form interposed between the flat lower end face of said cylinder block and cooperating end surfaces on said first and second case halves to provide a seal between said lower end face and said cooperating end surface and to come into close contact with upper end faces of said enlarged end portions, whereby a T-shaped intersecting joint area among said cylinder block and said first and second case halves is sealed by said seal member and said gasket.