Description

The Mercury / Quicksilver 8M0061068 Thermostat Cover Housing is a genuine OEM upper thermostat housing cover used on MerCruiser GM-based marine engines.

This component sits on top of the thermostat housing and seals the thermostat assembly, directing coolant flow into and out of the engine. It is a structural and sealing component, not a thermostat itself, and is critical for maintaining proper coolant circulation and system pressure.

The housing features an offset (diagonal) bolt pattern and is designed to work with big-block MerCruiser cooling systems. It replaces earlier designs while maintaining OEM fit and flow characteristics.

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Key Features

• Genuine Mercury / Quicksilver OEM part
• Thermostat housing upper cover / cap
• Maintains proper coolant flow and sealing
• Designed for high-flow big block cooling systems
• Corrosion-resistant marine construction
• Direct OEM replacement

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Engine Compatibility

MerCruiser GM-Based Engines

Commonly used on:

• 454 CID (7.4L) V8
• 502 CID (8.2L) V8
• High-performance big block engines

Typical Applications

• MCM (sterndrive)
• MIE (inboard)
• TRS and Bravo systems

Found on engines such as:

• 330 / 340 / 370 / 400 / 420 / 425 / 440 models
• 454 MAG Alpha
• 7.4L and 8.2L big block platforms (1980s–1990s era)

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Serial Number Fitment Notice

Fitment depends on:

• Engine displacement (454 / 502)
• Cooling system configuration
• Housing bolt pattern

Always confirm compatibility using your engine serial number before ordering.

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Specifications

• Part Number: 8M0061068
• Type: Thermostat housing cover
• Function: Seals thermostat housing and directs coolant flow
• Bolt Pattern: Offset / diagonal
• Material: Marine-grade cast metal
• Weight: 1.5 lbs

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What’s Included

• Thermostat housing cover only
  (Gasket and thermostat sold separately)

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When This Part Needs Replacement

• Coolant leak at thermostat housing
• Corrosion or pitting on sealing surface
• Warped or cracked housing
• Stripped or damaged bolt holes
• During full cooling system rebuild

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Installation Notes

• Always replace gasket when installing
• Clean mating surfaces completely
• Check thermostat housing base for corrosion
• Torque bolts evenly to avoid warping
• Pressure test cooling system after install

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Alternate / Superseded Part Numbers

OEM Cross References

• Mercury / Quicksilver: 8M0061068
• Supersedes: 47442A1 / 47442

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Shipping

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

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Parts Desk Insight

If you’re replacing this cover, inspect the lower housing too—on big blocks, corrosion usually affects both surfaces, not just the cap