Mercury 3-Cylinder Thermostat 825212T02

Mercury Thermostat 825212T02 is an OEM replacement thermostat for select Mercury and Mariner FourStroke engines. Mercury identifies this part as the 3-cylinder thermostat, with verified applications across several portable and midrange FourStroke engine families.

Compatible with select Mercury and Mariner FourStroke applications including:

• 8 HP
• 9.9 HP
• 13.5 HP
• 15 HP
• 25 HP
• 30 HP, including 3-cylinder carbureted and EFI models
• 40 HP, including select 3-cylinder models
• Select 45 HP and 50 HP applications

Mercury service information specifically lists 825212T02 as the thermostat used on compatible 30 HP 3-cylinder engines, while additional parts references show its use across the broader FourStroke range above.

The thermostat regulates cooling-water flow based on engine temperature, helping the engine reach and maintain its proper operating temperature. A thermostat that is sticking, corroded, or no longer opening at the correct temperature can contribute to cooling and operating-temperature problems.

The thermostat is rated at approximately 60°C / 140°F. The thermostat cover gasket is serviced separately under part number 824853.

Supersedes/Replaces: 825212001

To Confirm Compatibility: Contact our team with your engine serial number at (727) 596-5929 before ordering.