Thermostat Kit (130°F/54°C) – Fits Mercury Marine 200-300 HP Outboards (Replaces 8M0057307, 885599003)

Thermostat Kit (1306F/546C) 6 Fits Mercury Marine 200-300 HP Outboards (Replaces 8M0057307, 885599003)

This thermostat kit is designed for use with Mercury Marine 200-300 HP 6-cylinder outboard engines, including 2.5L, 3.0L, and 3.2L EFI/DFI engines and the Pro XS, Sport XS, and XS series.

It serves as a direct replacement for multiple Mercury and Sierra OEM part numbers, ensuring compatibility and straightforward installation.

• Includes 2 thermostats and 2 thermostat cover gaskets.
• Installation is a direct fit for specified Mercury Marine engine models.
• Temperature rating: 1306F (546C).

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, here9s a guide to help you identify your engine9s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

• 2 x Thermostats (8M0057307)
• 2 x Thermostat Cover Gaskets (27-8503181)

Installation Guide

1. Remove the old thermostat and gasket from your engine.
2. Clean the thermostat housing surface thoroughly to remove any debris or old gasket material.
3. Install the new thermostat into the housing.
4. Place the new gasket on top of the thermostat.
5. Reattach the thermostat cover securely.
6. Torque bolts to manufacturer specifications to avoid leaks.
7. Refill and check the coolant system for proper levels if applicable.
8. Start the engine and allow it to reach operating temperature to confirm proper thermostat function.

Troubleshooting & FAQ

How do I confirm this fits my engine?
Refer to the compatibility table and verify your engine's model, rated horsepower, and serial number range.

How often should I replace the thermostat?
Replace the thermostat as part of routine engine maintenance or if you experience overheating issues.

What are the differences between this aftermarket thermostat and the OEM part?
This listing is an aftermarket replacement part (not an OEM component). It is built to OEM specifications with comparable-grade materials and inspected for quality control in an ISO9002-certified facility.

What are common signs of a failing thermostat?
Engine overheating, fluctuating temperature gauge, and poor engine performance can indicate thermostat failure.

OEM vs. Aftermarket?
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.

How fast do you ship and how much does it cost?
We offer fast global shipping 7typically 515 days worldwide and standard shipping is free. Expedited options are available at checkout depending on your location.

What is your warranty and return policy?
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 515 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.