Mercury MerCruiser 160°F Thermostat - 8M0109441
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The Mercury MerCruiser Quicksilver 8M0109441 is a genuine Mercury Marine OEM 160°F thermostat used in select MerCruiser sterndrive, inboard, and Mercury/Mariner outboard cooling systems where the factory parts diagram calls for this thermostat. The thermostat regulates cooling-water or coolant flow through the engine so the motor can reach and maintain the correct operating temperature.
This thermostat opens at 160°F / 71°C and should be selected by exact engine serial number, cooling-system layout, and service manual specification before installation.
Key Features
- Genuine Mercury Marine OEM thermostat.
- Mercury/MerCruiser part number: 8M0109441.
- Operating temperature: 160°F / 71°C.
- UPC / GTIN reference: 745061286467.
- Used in select raw-water and closed-cooling systems where specified.
- Helps maintain proper engine operating temperature.
- Important service part for overheating, overcooling, slow warm-up, and stuck-thermostat symptoms.
- Listed shipping specs: 0.19 lb, 3.63 in. L x 2.25 in. W x 2.63 in. H.
- Supersedes earlier Mercury thermostat references in supported applications.
Engine Compatibility
Common application context includes select Mercury and MerCruiser engines where the factory parts diagram calls for 8M0109441, including:
- Select MerCruiser 3.0L inline-4 applications where specified.
- Select MerCruiser 4.3L V6 applications where specified.
- Select MerCruiser 5.0L and 5.7L V8 applications where specified.
- Select MerCruiser 6.2L / 377 CID V8 applications where specified.
- Select MerCruiser 7.4L / 454 CID and 8.2L / 502 CID applications where specified.
- Select Alpha and Bravo sterndrive or inboard engine packages using the matching thermostat housing and temperature rating.
- Select Mercury/Mariner outboard applications only where the OEM parts diagram confirms 8M0109441.
Use this thermostat only where the Mercury/MerCruiser parts diagram or service manual specifically calls for 8M0109441 or a confirmed replacement for the earlier thermostat reference.
Serial Number Fitment Notice
Confirm fitment by engine serial number, cooling-system type, thermostat housing style, gasket/seal layout, and required opening temperature before ordering. Similar MerCruiser engines may use different thermostats depending on year, cooling configuration, emissions package, housing design, and whether the engine is raw-water cooled or closed-cooled.
Do not substitute a 140°F thermostat or other temperature rating unless the engine service manual specifically calls for it.
When This Part Needs Replacement
Replace the thermostat if the engine runs too hot, runs too cool, takes too long to warm up, shows unstable operating temperature, overheats at idle, or fails thermostat testing. Replacement is also recommended during cooling-system service, thermostat housing repairs, corrosion cleanup, coolant contamination repairs, or when the thermostat is stuck open, stuck closed, corroded, scaled, or physically damaged.
Installation Notes
Drain the cooling system as required before removing the thermostat housing. Clean the thermostat seat and housing surfaces carefully, and replace the gasket, sleeve, seal, or O-ring shown in the same Mercury parts diagram. Do not reuse compressed, torn, or hardened sealing parts.
Install the thermostat in the correct orientation and use the torque specification from the MerCruiser service manual for the specific housing bolts. After installation, refill the cooling system as required, run the engine to operating temperature, check for leaks, and confirm stable temperature control.
Alternate/Superseded Part Numbers
- 8M0109441 — current Mercury/MerCruiser OEM part number
- 8072522 — earlier Mercury reference; verify by serial number and diagram
- 807252T2 — earlier Mercury reference; verify by serial number and diagram
- 745061286467 — UPC / GTIN reference
Related Service Parts
Depending on the engine diagram, thermostat service may also require related sealing parts such as the thermostat housing gasket, sleeve, O-ring, or cover gasket. Always confirm the matching gasket and seal numbers by engine serial number before ordering.
Parts Desk Insight
Thermostat temperature matters. A thermostat with the wrong opening temperature can cause poor warm-up, unstable idle quality, excess fuel use, overheating, or poor closed-cooling performance. Match the thermostat by engine serial number and required temperature rating, then replace the surrounding gasket or seal at the same time to prevent repeat leaks.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
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
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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.
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