Marine propulsion device with closed deck cylinder block construction

摘要

Disclosed herein is an engine comprising a closed deck cylinder block including a cylinder bore having an outer end, a counter bore at the outer end of the cylinder bore, and cylinder liner received in the cylinder bore and defining, with the counter bore, a U-shaped annular groove in the cylinder head mounting surface. A seal is located in the groove to provide a seal between the cylinder head and cylinder block. There is a pressure relief valve to control flow to the coolant jacket in the cylinder heat from the coolant jacket in the cylinder block. At low speeds the valve is closed so as to not overly cool the cylinder head.