Description

he Mercury MerCruiser Thermostat Seal 8071341 is a genuine OEM rubber sealing ring designed to properly seal the thermostat within the thermostat housing on GM-based MerCruiser engines. This seal ensures correct coolant flow direction and prevents internal bypass leakage, which is critical for maintaining proper engine operating temperature.

Manufactured from marine-grade rubber, this seal is built to withstand continuous exposure to heat, coolant, and raw water environments without degrading or losing sealing integrity. It is a direct replacement component typically used during thermostat service or replacement.

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Key Features

• Genuine Mercury MerCruiser / Quicksilver OEM seal
• Designed for thermostat-to-housing sealing
• Prevents coolant bypass and internal leakage
• Marine-grade rubber construction for durability
• Direct OEM fit — no modification required
• Critical component for proper cooling system operation

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Engine Compatibility

Fits a wide range of GM-based MerCruiser engines:

• 4.3L V6
• 5.0L V8 (305)
• 5.7L V8 (350)
• 7.4L V8 (454)
• 8.2L V8 (502)

Applications include:

• MerCruiser Alpha and Bravo sterndrives
• MerCruiser inboard engines
• Used in both raw water and some closed cooling thermostat housings

Commonly used with thermostat kits such as 807252T5 and 807252T4
Installed between thermostat and housing bore

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Serial Number Fitment Notice

Fitment can vary depending on thermostat housing design and engine serial number. Always confirm using your engine serial number or visually match your existing seal before ordering.

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When This Part Needs Replacement

• During thermostat replacement or service
• Coolant leaks at thermostat housing
• Engine not maintaining proper temperature
• Seal appears flattened, cracked, or brittle
• Preventative maintenance during cooling system service

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Installation Notes

• Lightly lubricate seal with clean coolant before installation
• Ensure seal is seated evenly in housing groove
• Do not reuse old seals — always replace when removed
• Inspect thermostat housing for corrosion or pitting
• Verify proper thermostat orientation before reassembly

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Alternate / Superseded / Cross-Reference Part Numbers

• Mercury / Quicksilver: 8071341
• Sierra: 18-0396
• GLM: 13110
• Often included in thermostat kits (e.g., 807252T5, 807252T4)

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Parts Desk Insight

This is a small but critical component. A worn or missing thermostat seal will cause improper coolant flow, often leading to engines running too cold or overheating inconsistently. It’s standard practice to replace this seal anytime the thermostat is serviced — reusing the old one is a common cause of repeat issues.

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Shipping

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