Mercury Thermostat, 160°F (GM MerCruiser V6 & V8 Closed Cooling) 991551

Mercury Thermostat, 160°F (GM MerCruiser V6 & V8 Closed Cooling) 991551 is a genuine Mercury/Quicksilver OEM replacement thermostat designed for compatible General Motors-based MerCruiser V6 and V8 engines with closed cooling systems. A properly functioning thermostat helps maintain the correct engine operating temperature for dependable performance, fuel efficiency, and long engine life.

Compatible with the following (1998 and newer w/ closed cooling):

• GM-based MerCruiser V6 engines
• GM-based MerCruiser V8 engines

This 160°F bypass thermostat is manufactured to Mercury Marine's OEM specifications for proper fit and reliable cooling system operation. Replacing a thermostat that is stuck open or closed helps restore proper engine temperature and supports efficient cooling system performance.

Always install the thermostat temperature specified in your owner's or service manual. Using the correct thermostat helps ensure proper cooling system operation and long-term engine reliability.

Quicksilver is Mercury Marine's official parts and accessories brand, offering the same OEM quality and fit as Mercury-branded components.

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