Patent ID: 8528515

Claim:
A crankcase of an internal combustion engine includes an upper crankcase half and a lower crankcase half, said upper crankcase half and said lower crankcase half respectively having an upper journal support wall and a lower journal support wall for cooperatively supporting a crank journal of a crankshaft, said upper journal support wall and said lower journal support wall being fastened together by a journal bolt mounted from a lower side of said crankcase, comprising: a wall portion for defining a space as a flow passage for a lubricating oil is formed below a journal bolt mounting surface of said lower crankcase half for mounting said journal bolt; and a tool insertion hole for insertion of a tool for tightening said journal bolt is formed through said wall portion, wherein said wall portion is located laterally outside of an oil pan of said internal combustion engine; and said wall portion is formed with an exit oil passage for discharging said lubricating oil from said space toward said oil pan.