1999 "EE" Evinrude 70HP 4-Stroke Service Manual, P/N 787023, Page 46Get this manual
Cooling System Components Thermostat
The thermostat is under removable cover at the top starboard rear of the cylinder blockIt' rated at 122 4F (50 2C), and opens only by water temperature
Water Pressure Valve
The water pressure valve is under removable cover at the top of the exhaust manifold water cooling passageIt opens at approximately 5.7 0.14 PSI (39,2 0,98 kPa), and will flow approximately 5.3 ga lminat PSI (20 litresmin at 49 kPa)Install carefully; if put in backwards, the manifold will overheatFresh Water Flushing Port
The fresh water flushing port is located along the lower rear edge of the oil reservoir on the port side of the engineUnscrew the plastic cap to install garden hoseThe engine can be flushed with the boat in or out of the water, with the engine run ning or not, or with the engine vertical or at full tiltThe cap will float if it falls in the wateris one exception to the aboveThe flushing system