Sierra 18-3618 Raw Water Cooled Thermostat Kit, 150 Degree, Volvo Penta I/O Cooling System

The Sierra 18-3618 is a raw water cooled thermostat kit built for Volvo Penta I/O engines that use a raw (open) cooling system, where river, lake, or sea water runs directly through the cylinder block. This kit uses a 150 degree Fahrenheit thermostat, which regulates the engine's operating temperature by controlling the flow of raw water through the cooling passages once the engine reaches that threshold. Maintaining the correct opening temperature protects against overheating in warm operating conditions while still allowing the engine to reach efficient running temperature quickly after startup.

As a raw water cooled thermostat, the 18-3618 is designed specifically for open cooling systems rather than closed (fresh water/antifreeze) systems, so it is important to match the thermostat type to your engine's cooling configuration. The kit carries Sierra's part number 18-3618 and is intended as a direct fit for the Volvo Penta I/O cooling system application it is listed for.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3618
• Product Type: Thermostat Kit
• Cooling System Type: Raw Water Cooled
• Thermostat Opening Temperature: 150 degrees Fahrenheit
• Application: I/O - Volvo Penta Cooling System
• Weight: 0.12 pounds
• UPC: 808282270599

Fitment

• Volvo Penta I/O engines with a raw water (open) cooling system, where raw water runs through the cylinder block

Frequently Asked Questions

What temperature thermostat is in the Sierra 18-3618 kit? The Sierra 18-3618 kit uses a 150 degree Fahrenheit thermostat, which opens at that temperature to regulate raw water flow through the engine.

Is the 18-3618 for a raw water or fresh water cooling system? It is a raw water cooled thermostat kit, meaning it is designed for open cooling systems where river, lake, or sea water runs directly through the cylinder block, not for closed fresh water/antifreeze systems.

What engines does the Sierra 18-3618 fit? This thermostat kit is intended for Volvo Penta I/O engines equipped with a raw water (open) cooling system.

How much does the Sierra 18-3618 thermostat kit weigh? The 18-3618 thermostat kit weighs 0.12 pounds.

What is the difference between the raw water and fresh water version of this thermostat? The raw water cooled version, part number 18-3618, is built for open cooling systems where outside water circulates through the engine block; a fresh water cooled version exists as a separate part number for closed cooling systems, so it is important to confirm which cooling system your engine uses before ordering.

What is included in the Sierra 18-3618 kit? The 18-3618 is sold as a thermostat kit under Sierra part number 18-3618.

Why does the raw water cooling system need a thermostat at all? In a raw water (open) cooling system, the thermostat still regulates when raw water is allowed to flow through the cylinder block, helping the Volvo Penta I/O engine reach and hold a stable operating temperature.

Is Sierra 18-3618 a genuine Sierra part or an aftermarket equivalent? The 18-3618 is a Sierra branded thermostat kit, sold under Sierra's own part number for the Volvo Penta I/O raw water cooling application.

What happens if I install the wrong opening temperature thermostat? Using a thermostat with the wrong opening temperature can cause the engine to run cooler or hotter than intended; the 18-3618 kit is specifically rated for a 150 degree Fahrenheit opening point for Volvo Penta I/O raw water cooled applications.

Can the 18-3618 be used on a closed (fresh water) cooling system? No, the 18-3618 is designated as a raw water cooled thermostat kit and is intended for open cooling systems where raw water runs through the cylinder block, not closed fresh water systems.