Thermostat (160°F/71°C) – Fits MerCruiser V6/V8 Alpha/Bravo Engines (Replaces 8M0109441, 807252T2)

Thermostat (160°F/71°C) – Fits MerCruiser V6/V8 Alpha/Bravo Engines (Replaces 8M0109441, 807252T2)

This thermostat is designed for Mercury MerCruiser V6 & V8 engines with standard cooling systems that require a 160°F thermostat. It is primarily used in 1987–present Alpha/Bravo sterndrives and inboards.

It serves as a direct replacement for Mercury/MerCruiser part numbers 8M0109441 (which supersedes 8M0091470, 807252T2, 8072522, and 8052732) and Sierra 18-3649.

• Temperature Rating: 160°F (71°C) opening temperature
• Installation: Direct replacement using standard tools
• Quality: Manufactured to OEM specifications in an ISO9002 certified factory

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

• 1 x Thermostat (8M0109441)

Installation Guide

1. Ensure the engine is completely cool before starting work.
2. Locate the thermostat housing, usually where the large coolant hose from the top of the engine connects.
3. Place a drain pan under the housing to catch any coolant that spills.
4. Unscrew the bolts holding the thermostat housing cover in place.
5. Gently remove the cover. Take note of how the old thermostat is positioned before removing it.
6. Take out the old thermostat and its gasket. Thoroughly clean the gasket mating surfaces on both the housing and the cover.
7. Insert the new thermostat, making sure it is oriented in the same direction as the original.
8. Position the new gasket correctly on the housing.
9. Re-attach the housing cover and tighten the bolts to the manufacturer's recommended torque specification.
10. Refill the cooling system with the correct type and amount of coolant.
11. Start the engine and carefully check for leaks around the thermostat housing.
12. Let the engine run until it reaches normal operating temperature to confirm the new thermostat opens properly.

Troubleshooting & FAQ

Q: How do I confirm this thermostat fits my MerCruiser engine?

A: This thermostat fits a wide range of V6 and V8 MerCruiser Alpha/Bravo engines from 1987 to the present. The best way to confirm is to match your engine's serial number with the ranges listed in the "Compatible Engine Models" table or to cross-reference your existing part number with 8M0109441, 807252T2, or Sierra 18-3649.

Q: What are the signs of a failing thermostat?

A: Common signs include the engine overheating, the temperature gauge reading unusually low, or significant fluctuations in engine temperature. A thermostat stuck open will prevent the engine from reaching its proper operating temperature, while one stuck closed will cause it to overheat quickly.

Q: Why is a 160°F thermostat used in marine engines?

A: A 160°F (71°C) thermostat is specified for standard raw water cooled marine engines to ensure they reach the optimal operating temperature quickly without overheating. This helps improve fuel efficiency, reduce engine wear, and prevent the buildup of carbon deposits.

Q: Is a gasket included with this thermostat?

A: The package contains one thermostat. Gaskets are typically sold separately and should be replaced during installation to ensure a proper seal.

Q: OEM vs. Aftermarket?

A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?

A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?

A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.