Description

The Mercury MerCruiser Thermostat 76270T is a genuine OEM 160°F thermostat designed primarily for early MerCruiser 3.7L (470/485) inline 4-cylinder engines. This thermostat regulates engine temperature by controlling coolant flow, ensuring proper warm-up, stable operating temperature, and prevention of overheating.

This is a direct replacement for the original thermostat (76270), updated to the current “T” suffix version. It is specifically calibrated for raw water cooling systems commonly used on these engines, maintaining correct thermal balance for efficient combustion and engine longevity.

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Key Features

• Genuine Mercury MerCruiser / Quicksilver OEM thermostat
• 160°F temperature rating (standard for raw water cooling)
• Direct replacement for part number 76270 (superseded)
• Designed for consistent engine temperature regulation
• Corrosion-resistant construction for marine environments
• Thermostat only (no gaskets or seals included)

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Engine Compatibility

Primarily used on:

• MerCruiser 3.7L (470 / 485) inline 4-cylinder engines
• Model years approximately 1976–1982

Applications include:

• MerCruiser sterndrive (early Alpha systems)
• MerCruiser inboard variants using the 3.7L platform

Designed for raw water cooled systems
Not interchangeable with later GM V6/V8 thermostat kits

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Serial Number Fitment Notice

Fitment is highly specific on 3.7L engines. Always confirm using your engine serial number or original part number before ordering. These engines have unique cooling system layouts compared to GM-based MerCruiser engines.

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When This Part Needs Replacement

• Engine running too cold or overheating
• Slow warm-up or inconsistent temperature
• Thermostat stuck open or closed
• Corrosion or scaling found during inspection
• Cooling system service on older 3.7L engines

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Installation Notes

• Replace gasket and seal (sold separately) during installation
• Install with spring side facing engine block
• Clean housing thoroughly before reinstalling
• Inspect water passages for corrosion (common on 3.7L engines)
• Verify proper circulation after startup

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Alternate / Superseded / Cross-Reference Part Numbers

• Mercury / Quicksilver: 76270T
• Supersedes: 76270
• Sierra: 18-3552 (kit equivalent)
• Aftermarket references may include: 27-896561, 99155A1 equivalents

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Parts Desk Insight

This thermostat is specific to the MerCruiser 470/485 platform, which uses a unique cooling system compared to standard GM-based engines. These engines are known for corrosion issues in cooling passages — if you’re replacing the thermostat, it’s a good time to inspect the entire system. Also note this is not interchangeable with 807252-series thermostat kits used on V6/V8 engines.

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Shipping

Shipping: Ships same or next day for fast Canada wide shipping.