Thermostat Repair Service Kit for Mercury Marine 2 Stroke 70-125 HP Outboard Motors 803061T1

Thermostat Kit – Fits Mercury/Mariner 70-125 HP 2-Stroke Outboards (Replaces 803061T1)

This thermostat kit is designed for Mercury/Mariner 70-125 HP 2-stroke inline 3 & 4 cylinder outboards from 1987 and newer. It ensures your engine maintains the correct operating temperature for optimal performance and longevity.

This kit is a direct replacement for Mercury part number 803061T1 and other common aftermarket versions, ensuring a precise fit and reliable function for your cooling system.

• Includes all necessary components: thermostat, seal, gasket, and washer.
• Maintains a consistent operating temperature of 122°F / 50°C.
• Engineered as a direct OEM-quality replacement for easy 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 (14586)
• 1 x Thermostat Seal (62386001)
• 1 x Thermostat Cover Gasket (430068)
• 1 x Washer (47533)

Installation Guide

1. Safety First: Ensure the engine is off and cool. Disconnect the battery's negative terminal.
2. Drain Coolant: Place a container under the engine and drain the cooling system to a level below the thermostat housing.
3. Access Housing: Locate and remove the bolts securing the thermostat housing cover. Note their positions for reassembly.
4. Remove Old Parts: Carefully lift off the cover. Remove the old thermostat, gasket, and seal.
5. Clean Surfaces: Thoroughly clean the mating surfaces of the housing and cover, removing any old gasket residue.
6. Install New Kit: Place the new thermostat into the housing, followed by the new seal and gasket as per the original orientation.
7. Reassemble: Re-position the housing cover and tighten the bolts evenly in a crisscross pattern to the manufacturer's recommended torque.
8. Refill and Check: Refill the cooling system with the appropriate coolant. Reconnect the battery.
9. Test for Leaks: Start the engine and let it run for several minutes, checking for any leaks around the housing. Monitor the temperature gauge to ensure it stabilizes at the correct temperature.

Troubleshooting & FAQ

Q: How do I confirm this fits my engine?

A: This kit is designed for Mercury/Mariner 70-125 HP 2-stroke inline 3 & 4 cylinder outboards (1987+). To ensure a perfect match, please consult the "Compatible Engine Models" table and verify that your original part number is 803061T1.

Q: What are the signs of a faulty thermostat?

A: Common symptoms include the engine overheating, running too cool (not reaching operating temperature), or having erratic temperature readings on the gauge. A faulty thermostat can lead to poor performance, increased fuel consumption, and engine damage.

Q: How often should I replace my outboard's thermostat?

A: Thermostats are a critical maintenance item. It is recommended to inspect and potentially replace them every 1-2 years or every 100-200 hours of operation, especially if you operate in saltwater, to prevent corrosion and sticking.

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.