Coolant Thermostat SIERRA 18-3557

Compatible Engines

The SIERRA 18-3557 coolant thermostat is a vital component of the cooling system, ensuring optimal operating temperature for your power unit. It opens at 62 °C (143 °F), which is the standard for many outboard and inboard boat engine designs. Due to the complexity of the aftermarket parts market, we do not provide a specific list of engine brands or models, as compatibility can vary significantly depending on the year and engine version. To ensure 100% accuracy, verify fitment by comparing catalog number 18-3557 with the OE (original) number in your unit's technical documentation. If you have any doubts about part selection, contact our customer support – we are happy to assist with verification.

Installation and Operation

Replacing the thermostat requires precision. Before disassembly, ensure the engine is cold and the cooling system is drained. Use only fresh coolant compatible with the engine manufacturer's recommendations to prevent corrosion and scale buildup. After installing the new SIERRA 18-3557 thermostat, thoroughly check all connections for leaks and bleed the system to avoid overheating during initial voyages.

• Original SIERRA quality – guarantee of durability and manufacturing precision.
• Correct opening temperature – 62 °C ensures rapid heating and stable operation.
• Safe replacement – protects the engine from overheating and mechanical damage.
• Easy identification – catalog number 18-3557 simplifies finding the correct replacement.