Mercury - Quicksilver 160 Degree Thermostat Engine Cooling System Standard Marine Construction 8M0109441. Overview. Every boater has that one moment when something as simple as temperature makes or breaks the day. Maybe it is the smooth pull onto plane when everything is running just right, or the quiet rumble as you idle along a shoreline without a hint of hesitation. That kind of confidence comes from an engine held at the perfect operating temperature. The Quicksilver 160 Degree Thermostat de