143°F Thermostat Kit – Fits Mercury/Mariner 135-200HP V6 Outboard Engines (Replaces 75692Q2, GLM 13340)

143°F Thermostat Kit – Fits Mercury/Mariner 135-200HP V6 Outboard Engines

This thermostat kit is designed for a wide range of Mercury and Mariner 135–200HP V6 outboard engines, including popular XR4, XR6, Magnum II, Magnum III, and various V-series models. Primarily fitting engines from the 1990s through the early 2000s, compatibility is determined by specific serial number ranges.

This kit serves as a direct replacement for multiple OEM and aftermarket part numbers, ensuring broad applicability for routine maintenance and repairs.

• Operating Temperature: Maintains a consistent engine temperature of 143°F (61.7°C).
• Complete Kit: Includes two thermostats with seals/gaskets, as required for V6 models.
• Installation Method: Designed for direct replacement of the original factory parts.

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

This kit includes:

• 2 x Thermostat with seals/gaskets (equivalent to 75692Q2)

Installation Guide

1. Safety First: Disconnect the battery cables before beginning work.
2. Locate Housing: Find the thermostat housing on the engine block; it is typically on top of the cylinder heads.
3. Drain Coolant: Partially drain the engine's cooling system so the coolant level is below the thermostats.
4. Remove Cover: Unbolt and remove the thermostat housing cover.
5. Extract Old Parts: Carefully take out the old thermostat and its gasket or seal. Note its orientation.
6. Clean Surfaces: Thoroughly clean the mating surfaces of the housing and cover, removing any old gasket material.
7. Install New Parts: Place the new thermostat and seal into the housing, ensuring it is seated correctly.
8. Reassemble: Reattach the housing cover and tighten the bolts to the manufacturer's recommended torque.
9. Refill System: Top off the cooling system with the appropriate coolant.
10. Final Check: Reconnect the battery, start the engine, and carefully check for any leaks around the housing. Monitor the engine temperature to ensure it is operating correctly.

Troubleshooting & FAQ

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

A: Compatibility is primarily based on your engine's serial number, not just the model year. Please check the compatibility table and use our Mercury Serial Number Guide to verify your engine's details. This kit fits many V6 models from the 1990s to early 2000s but will not fit DFI Optimax motors.

Q: What are the signs of a failing thermostat?

A: Common signs include the engine overheating at high speeds, running too cold at idle, erratic temperature gauge readings, or engine performance issues. An engine alarm may also sound if the temperature goes out of the normal range.

Q: How many thermostats are in this kit?

A: This kit includes two thermostats with their corresponding seals. This is because V6 outboards require two thermostats for proper temperature regulation across both cylinder banks.

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.