Outboard Thermostat for Mercury Marine 1.5L 2.5L 75-175 HP DFI Outboard Motors 833072003

Outboard Thermostat – Fits Mercury Marine 75-175 HP DFI (Replaces 833072003)

This aftermarket thermostat is engineered to regulate engine temperature for select Mercury Marine, Optimax, and Mercury Mariner outboard motors. It ensures your engine operates within the correct temperature range for optimal performance and longevity.

It serves as a direct replacement for Mercury part numbers 833072, 833072002, 833072003, and 833072004, as well as Sierra 18-3536.

• Installation Method: Direct Replacement
• Operating Temperature: 143°F (61.6°C)
• Important Note: Requires thermostat seal 27-887978, which is not included with this part.

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 Mercury Outboard Thermostat (Replaces 833072/833072002/833072003/833072004)
• Note: Thermostat seal (part number 27-887978) is required for installation and is not included.

Installation Guide

1. Disconnect Battery: Disconnect the negative battery cable to prevent electrical shorts.
2. Drain Coolant: Drain the engine's cooling system to a level below the thermostat housing.
3. Locate Housing: Identify and access the thermostat housing on the engine block.
4. Remove Housing: Carefully unbolt and remove the thermostat housing cover.
5. Remove Old Thermostat: Take out the old thermostat and the corresponding seal or gasket.
6. Clean Surfaces: Thoroughly clean the mating surfaces of the housing and engine block.
7. Install New Thermostat: Insert the new thermostat, ensuring it is correctly oriented. Install the new seal (sold separately).
8. Re-install Housing: Secure the housing cover and tighten the bolts to the manufacturer's recommended torque.
9. Refill Coolant: Refill the cooling system with the appropriate coolant.
10. Check for Leaks: Reconnect the battery, start the engine, and carefully inspect for any leaks around the housing as the engine warms up.

Troubleshooting & FAQ

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

A: First, review the "Compatible Engine Models" table. For Mercury owners, we highly recommend using the linked guides to verify your engine's serial number and model against the listed applications. This part is specifically for certain Mercury 1.5L and 2.5L DFI engines.

Q: What are the common signs of a failing thermostat?

A: A faulty thermostat can cause your engine to overheat, fail to reach its normal operating temperature, or show erratic temperature gauge readings. Replacing it can restore proper engine temperature regulation.

Q: Is the necessary seal included with this thermostat?

A: No. The required thermostat seal (Mercury part 27-887978) is not included in this package and must be acquired separately to ensure a proper, leak-free installation.

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.