Outboard motor with improved engine lubrication system

An internal combustion engine comprising

• a cylinder block which defines a cylinder,
• a crankshaft bearing supported at least in part by said cylinder block,
• a crankshaft which is rotatably supported by said crankshaft bearing,
• a piston slidably housed in said cylinder,
• a connecting rod having one end connected to said piston and having an opposite end connected to said crankshaft,
• a cylinder head mounted on said cylinder block,
• a camshaft at least partially supported by said cylinder head for rotation relative thereto,
• an oil pump having an outlet,
• a first oil conduit communicating between said oil pump outlet and said crankshaft bearing,
• an oil filter communicating with said first oil conduit for filtering oil only in said first oil conduit, and
• a second oil conduit communicating between said oil pump outlet and said camshaft, oil in said second oil conduit being unfiltered between said pump outlet and said camshaft.

An outboard motor comprising

• a driveshaft housing,
• a propeller rotatably supported by said driveshaft housing,
• an oil reservoir, and
• an internal combustion engine including
• a cylinder block which is supported by said driveshaft housing, which has a bottom surface, and which defines a cylinder,
• a crankshaft bearing supported at least in part by said cylinder block,
• a crankshaft which is rotatably supported by said crankshaft bearing and which is drivingly connected to said propeller, said crankshaft including a crankshaft bearing surface engaging said crankshaft bearing, said crankshaft also including a connecting rod bearing surface, and said crankshaft having therein an oil passageway extending from said crankshaft bearing surface to said connecting rod bearing surface,
• a piston slidably housed in said cylinder,
• a connecting rod having one end connected to said piston and having an opposite end connected to said crankshaft at said connecting rod bearing surface,
• a cylinder head mounted on said cylinder block, said cylinder head having a bottom surface,
• a camshaft at least partially supported by said cylinder head for rotation relative thereto, said camshaft having a lower end and an outer surface including upper and lower camshaft bearing surfaces, said outer surface having therein a groove which extends from said upper camshaft bearing surface to a point below said upper camshaft bearing surface,
• an oil pump which is mounted on said bottom surface of said cylinder head and which is driven by said lower end of said camshaft, said oil pump having an inlet and an outlet,
• a first oil conduit communicating between said oil reservoir and said oil pump inlet,
• a second oil conduit communicating between said oil pump outlet and said crankshaft bearing,
• a third oil conduit communicating between said oil pump outlet and said camshaft upper bearing surface, such that said groove in said camshaft moves into and out of alignment with said third oil conduit during each rotation of said camshaft, such that said groove receives oil from said third oil conduit when said groove is aligned with said third oil conduit, and such that said groove conducts oil received from said third oil conduit along said camshaft to lubricate portions of said camshaft below said upper camshaft bearing surface,
• an oil filter communicating with said second oil conduit for filtering oil only in said second oil conduit, said oil filter being the only oil filter communicating with said second and third oil conduits, and
• an oil pressure regulator valve mounted on said bottom surface of said cylinder block, said valve communicating with said second oil conduit upstream of said oil filter, said valve also communicating with said oil reservoir and allowing oil flow from said second oil conduit to said oil reservoir when the oil pressure in said second oil conduit is greater than a predetermined value.