Mercury Thermostat – 8M0168892

Your 40-60 hp Mercury four-stroke depends on a tight 120 °F operating window to idle smoothly, pull hard, and sip fuel. This genuine OEM thermostat slots into the cylinder-head housing and reacts the instant coolant creeps past spec. A copper-wax heat capsule nudges the stainless slide valve open, letting just enough water circulate to keep temperatures right on target—no hunting, no sudden spikes.

What sets it apart?

• Exact 120 °F calibration maintains factory cooling curves for EFI models 1C050252-up.

• Stainless support cage shrugs off vibration and corrosion, even in brackish backwaters.

• Copper wax pellet responds quickly for tighter temperature control at troll or WOT.

• Integrated rubber seal seats flush against the head recess, eliminating the need for extra gaskets.

Swap this thermostat any time you see creeping temps, steam at the tell-tale, or an engine that never quite warms up. Ten minutes with basic tools restores peak efficiency, protects cylinder liners, and lets you spend the afternoon chasing stripers instead of troubleshooting an overheat alarm.