Thermostat – Fits Volvo Penta Marine Engines (Replaces 861911)
Thermostat – Fits Volvo Penta Marine Engines (Replaces 861911) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Thermostat – Fits Volvo Penta Marine Engines (Replaces 861911)
Product Details
This is an aftermarket Thermostat that fits Volvo Penta Marine Engines (Replaces 861911), specifically designed for models like the 4.3L, 5.0L, and 5.7L series equipped with raw water cooling systems. It maintains a consistent operating temperature of 150°F (66°C) to ensure optimal engine performance and longevity.
This part serves as a direct replacement for Volvo Penta 861911 and is equivalent to aftermarket parts such as Sierra 18-3615 and the Sierra 18-3618 kit.
- Engineered for direct drop-in installation.
- Designed for use in raw water cooling systems.
- Maintains a stable 150°F (66°C) operating temperature.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Volvo Penta | 861911 | OEM |
| Sierra | 18-3615 | 150°F Thermostat |
| Sierra | 18-3618 | Thermostat Kit |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This thermostat is designed for specific Volvo Penta gasoline engines. Please verify your model is listed.
| Brand | Model | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|
| Volvo Penta | 4.3L | 4-Stroke | 861911 | Raw water cooling |
| Volvo Penta | 5.0L | 4-Stroke | 861911 | Raw water cooling |
| Volvo Penta | 5.7L | 4-Stroke | 861911 | Raw water cooling |
Technical Specs
- Product Type
- Marine Engine Thermostat
- Installation
- Direct Drop-In
- Fuel Type
- Gasoline
- Connection
- Raw Water Cooling System
- Dimensions
- Height: 11.0 in; Width: 6.0 in; Length: 6.0 in;
- Fitting Type
- Direct OEM Replacement
- Operating Temperature
- 150°F (66°C)
- Warranty
- Manufacturer Standard Warranty
- Other Technical Attributes
- Raw Water Cooling System Application
What’s in the Box
- 1 x Thermostat (Replaces 861911)
Installation Notes
- Disconnect the vessel's battery before starting any work.
- Drain the engine cooling system to a level below the thermostat housing.
- Locate and unbolt the thermostat housing. Be prepared for some residual coolant spillage.
- Remove the old thermostat and gasket. Note the orientation of the old thermostat.
- Thoroughly clean the mating surfaces of the thermostat housing and engine block.
- Install the new thermostat in the correct orientation.
- Place the new gasket onto the housing and reinstall it, tightening the bolts to the manufacturer's specified torque.
- Refill the cooling system with the appropriate coolant.
- Reconnect the battery, start the engine, and check for any leaks around the housing as the engine warms up.
Troubleshooting & FAQ
How do I know if this thermostat fits my engine?
This thermostat is compatible with Volvo Penta 4.3L, 5.0L, and 5.7L gasoline engines that use a raw water cooling system. Always cross-reference your specific engine model and year with the compatibility table and verify the OEM part number is 861911.
What are the signs of a failing thermostat?
Common symptoms of a faulty thermostat include engine overheating (if stuck closed) or the engine failing to reach its normal operating temperature (if stuck open). You may also notice erratic temperature gauge readings or poor engine performance.
Why is the 150°F temperature important?
The 150°F (66°C) rating is specific to raw water (saltwater or lake water) cooled engines. Using a thermostat with a different temperature rating can lead to improper engine performance, increased corrosion, or salt buildup in the cooling passages.
Do I need a new gasket for installation?
Yes, it is always recommended to use a new gasket when replacing a thermostat to ensure a proper seal and prevent coolant leaks. This package contains the thermostat only; gaskets must be sourced separately or as part of a kit like the Sierra 18-3618.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It's built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, it's batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
This product is covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
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