MerCruiser Thermostat 160°F – 8M0076464 (496 MAG / 8.1L Big Block)
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
The Mercury / Quicksilver 8M0076464 Thermostat is a genuine OEM 160°F (71°C) thermostat designed specifically for MerCruiser 8.1L big-block engines, including 496 MAG platforms.
This thermostat regulates coolant flow within the engine to maintain proper operating temperature. The 160°F calibration is critical for these engines to ensure correct combustion efficiency, fuel control, and long-term durability under marine load conditions.
Built to Mercury Marine OEM standards, it uses a wax-element valve that opens progressively with temperature, providing stable cooling performance across idle and high RPM operation.
Key Features
- Genuine Mercury / Quicksilver OEM part
- 160°F (71°C) temperature rating
- Designed for big-block MerCruiser engines
- Maintains optimal engine operating temperature
- Prevents overheating and cold-running conditions
- Durable, corrosion-resistant construction
- Direct OEM replacement
Engine Compatibility
MerCruiser Big Block Engines
- 496 MAG (8.1L)
- 496 MAG HO
- 8.1L Inboard (V-Drive & Inline)
➡️ Used on:
- Sterndrive and inboard applications
- Big-block GM-based marine engines
Serial Number Fitment Notice
Fitment depends on:
- Engine model (496 MAG / 8.1L variants)
- Cooling system configuration
⚠️ Always confirm compatibility using your engine serial number before ordering.
Specifications
- Part Number: 8M0076464
- Temperature Rating: 160°F (71°C)
- Type: Engine thermostat
- Operation: Wax-element, spring-loaded
- Application: MerCruiser big-block cooling systems
What’s Included
- Thermostat only
(Gasket or seal sold separately unless specified)
When This Part Needs Replacement
- Engine overheating
- Engine running too cold
- Temperature fluctuations
- Sticking due to corrosion or debris
- Routine service on high-hour engines
Installation Notes
- Install with spring facing engine
- Replace gasket/seal during install
- Clean housing thoroughly
- Verify operating temp after install
Alternate / Superseded Part Numbers
OEM Cross References
- Mercury / Quicksilver: 8M0076464
- Supersedes: 863358T
Shipping
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
💡 Parts Desk Insight
This is big-block specific—don’t mix it with small-block 160° thermostats. Same temp, totally different fit 👍
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.