SIERRA 18-3553 Thermostat

Maximize performance and efficiency by running your engine at the optimum temperature

A failed thermostat can cause an engine to run at outside of its optimum temperature and can adversely affect performance and efficiency. The fix can be as simple as replacing the thermostat. This Sierra thermostat is engineered with a temperature rating of 143° and is compatible with many Mercury outboards.

For 50 years Sierra has been producing parts engineered to meet or exceed the specifications of marine engine manufacturers and has gained the confidence of engine manufacturers and boat builders. Boaters and technicians can be assured a Sierra part will fit right the first time and restore function to OEM specifications.

Key Features

• Thermostat meets or exceeds manufacturer specifications
• Temperature rating of 143°
• Compatible with many Mercury outboards; use the list below or our Engine Part Selector to confirm this thermostat is right for your engine

The Sierra Engine Parts Selector

In addition to thermostats, we offer a wide variety of other engine parts manufactured by Sierra. To see if we have the part you need, see our Engine Parts Selector, where you can search by engine make, serial number and model or year of manufacture.