A reliable thermostat might not get much attention, but it’s one of those unsung parts that keeps everything running smooth, especially on marine engines that work hard in constantly changing water conditions. The Mercury Marine 160 Degree Thermostat - 8M0109441 is built for exactly that — maintaining consistent operating temperatures on GM-based marine engines from 1987 and newer, equipped with standard cooling systems.

Holding steady at 160 degrees, this thermostat helps the engine reach its ideal operating temp quickly, then locks it in for efficient fuel burn, strong performance, and long-term protection against overheating. Designed to Mercury’s exacting specs, it’s a precise fit with the durability to handle exposure to raw water, constant heat cycling, and the demands of high-RPM runs.

What makes it worth installing:

• Calibrated for 160 degrees to balance performance, efficiency, and component longevity
• Compatible with 1987 and newer GM V6 and V8 marine engines using standard cooling systems
• Corrosion-resistant build stands up to saltwater and fluctuating temperatures
• OEM fit for clean installation with no guesswork or modifications

Ideal uses:

1. Routine thermostat replacements during cooling system maintenance
2. Restoring consistent temperature regulation on aging GM-based marine engines
3. Keeping engine temps stable in shifting water conditions — from cold morning starts to hot afternoon runs

For boaters who know the value of consistent cooling, this Mercury thermostat offers the kind of reliability that keeps engines running strong trip after trip.