Sierra 18-3619 Thermostat Kit for Fresh Water Cooled Marine Engines

The Sierra 18-3619 is a complete thermostat kit built for fresh water cooled marine engines, replacing a worn or stuck thermostat so the engine holds a stable, correct operating temperature. A fresh water cooled engine relies on the thermostat to regulate coolant flow through the closed cooling loop, and a failed unit can cause overheating, poor fuel efficiency, or an engine that never reaches proper operating temperature. This kit gives boat owners and marine technicians a straightforward, engineered replacement rather than sourcing individual pieces separately.

The thermostat features a machined exterior for a precise, consistent fit in the housing it is installed into. Sierra builds this kit to meet or exceed the performance of the original equipment part it replaces, so installation and operation match what the engine was originally designed around. Its compact dimensions keep it a close match for the factory thermostat cavity, and the kit is sized for engines using a fresh water cooling arrangement rather than raw water cooling.

This part is commonly used on Volvo Penta engines within the fresh water cooling category, and is intended as a direct maintenance replacement during routine cooling system service or when diagnosing overheating issues.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3619
• Product Type: Thermostat Kit, Fresh Water Cooled
• Cooling System Type: Fresh Water Cooled
• UPC: 808282270605
• Weight: 0.17 pounds
• Product Dimensions: 0.39 x 0.39 x 0.39 inches
• Exterior Finish: Machined
• Compatible Application: Volvo Penta fresh water cooled engines

Fitment

Designed for Volvo Penta fresh water cooled marine engines.

Replaces (OEM)

No OEM cross-reference numbers are listed for this part.

Frequently Asked Questions

What engines is the Sierra 18-3619 thermostat kit designed for? The Sierra 18-3619 thermostat kit is designed for Volvo Penta fresh water cooled marine engines, where it regulates coolant temperature within the closed cooling loop.

Is this a fresh water cooled or raw water cooled thermostat? It is a fresh water cooled thermostat kit, meaning it is built for engines that use a closed, fresh water cooling loop rather than drawing raw water directly through the block.

How much does the 18-3619 thermostat kit weigh? The Sierra 18-3619 weighs 0.17 pounds.

What are the dimensions of the Sierra 18-3619 thermostat? The thermostat measures 0.39 x 0.39 x 0.39 inches.

What finish does the Sierra 18-3619 thermostat have? It has a machined exterior finish for a precise fit in the thermostat housing.

Does the 18-3619 kit meet OEM performance standards? Sierra builds the 18-3619 thermostat kit to meet or exceed the performance of the original equipment part it replaces.

What signs indicate my thermostat needs replacing with the 18-3619 kit? Engine overheating, an engine that runs consistently cool, or fluctuating temperature gauge readings are common signs a fresh water cooled engine's thermostat, such as the Sierra 18-3619, needs replacement.

Is installation of the 18-3619 thermostat kit something a boat owner can do themselves? The Sierra 18-3619 is a direct maintenance replacement thermostat kit, sized to match the factory thermostat cavity, making it suitable for routine cooling system service by an owner comfortable with basic engine maintenance or a marine technician.

What is included in the Sierra 18-3619 thermostat kit? The 18-3619 is sold as a complete thermostat kit rather than a bare thermostat alone, giving you the components needed for the replacement in one package.

Is the Sierra 18-3619 a genuine Sierra part or aftermarket? The 18-3619 is manufactured by Sierra as a direct replacement part, engineered to meet or exceed the original equipment component it replaces on applicable Volvo Penta fresh water cooled engines.

What is the UPC for the Sierra 18-3619 thermostat kit? The UPC for the Sierra 18-3619 Thermostat Kit - Fresh Water Cooled is 808282270605.