Thermostat Kit for Mercury Verado 135-300 HP (Replaces 892864T04, 18-3631)

Thermostat Kit for Mercury Verado 135-300 HP (Replaces 892864T04, 18-3631)

This thermostat kit is designed for Mercury and Mariner Verado four-stroke outboard engines from 135HP to 300HP (2005–present). It ensures your engine maintains its optimal operating temperature by precisely regulating coolant flow.

This component is a direct replacement for Mercury part numbers 892864T04, 8M0174561, and Sierra 18-3631.

• Engine Compatibility: Mercury/Mariner Verado 135-300HP 4-Stroke (2005+)
• Installation Method: Direct Replacement
• Key Components: Includes thermostat, O-ring seal, and clamp for a complete installation.

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 Assembly (replaces 892864T04)
• 1 x O-ring Seal (replaces 8M005958)
• 1 x Clamp (replaces 888988008)

Installation Guide

1. Ensure the engine is completely cool before starting. Disconnect the battery for safety.
2. Drain the engine coolant into a suitable container.
3. Locate the thermostat housing on the engine block.
4. Carefully remove the bolts or clamps securing the housing. Note the orientation of the old thermostat.
5. Remove the old thermostat and O-ring seal. Clean the housing surfaces thoroughly.
6. Install the new thermostat in the correct orientation, followed by the new O-ring seal.
7. Secure the housing with the original bolts or the new clamp provided.
8. Refill the cooling system with the recommended coolant type.
9. Reconnect the battery. Start the engine and check for any leaks around the housing as it reaches operating temperature.

Troubleshooting & FAQ

Q: How do I confirm this thermostat kit fits my engine?
A: First, check the Compatible Engine Models table on this page. Second, verify that your existing part number matches one of the numbers listed in our Part Number Cross-Reference section (Mercury 892864T04, 8M0174561, or Sierra 18-3631).

Q: What are the signs of a failing thermostat?
A: Common symptoms include the engine overheating (temperature gauge running hot) or the engine failing to reach its normal operating temperature, which can lead to poor performance and fuel efficiency.

Q: What is the operating temperature of this thermostat?
A: This thermostat has a nominal opening temperature of 144°F (62°C) to ensure your engine operates in the correct temperature range.

Q: Is this an OEM or aftermarket part?
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.