Mercury Quicksilver Thermostat 130°F – 8M0057307
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Mercury Quicksilver Thermostat 130°F — 3.0L V6 OptiMax Outboard
Part Number: 8M0057307 | GTIN: 745061562318
Brand: Mercury / Quicksilver | Temperature Rating: 130°F / 54°C
Genuine Mercury Quicksilver OEM 130°F thermostat for selected 3.0L V6 Mercury OptiMax outboards. Self-cleaning design allows contaminants to flush through the thermostat’s closing surfaces, helping to maintain reliable operation in marine environments.
Compatible Applications
- Mercury 200 HP 3.0L V6 DFI / OptiMax — S/N 1B227000 and higher (non-Pro models)
- Mercury 225 HP 3.0L V6 DFI / OptiMax — S/N 1B227000 and higher (non-Pro models)
- Additional 3.0L V6 OptiMax applications — verify by serial number and model
Racing and Pro-series 3.0L/3.2L engines may also reference this part through superseded numbers. Confirm engine serial number and model before ordering.
When This Part Needs Replacement
Replace the thermostat when cooling-system diagnosis shows it is sticking open or closed, when the engine is running outside its normal operating-temperature range, or when thermostat replacement is called for during scheduled cooling-system maintenance.
Installation Notes
Allow the engine to cool completely before beginning service. Inspect the thermostat cavity, cover, and sealing surfaces for corrosion or debris. Thermostat gaskets are separate items on applicable cylinder-head assemblies — inspect and replace sealing components as required. Follow the applicable Mercury outboard service manual for torque specifications and procedures.
Related Products
- Sierra 9253 Outboard Maintenance Kit | Mercury V6 OptiMax 3.0L (S/N 1B227000+, Non-Pro)
- Sierra 9252 Outboard Maintenance Kit | Mercury V6 OptiMax 2.5L (S/N 1B227000+, Non-Pro)
Alternate & Superseded Part Numbers
- Current OEM: 8M0057307
- Supersedes: 8855991
- Supersedes: 885599003
- Supersedes: 885599004
- Sierra cross-reference: 18-3535
- GTIN: 745061562318
Parts Desk Insights
The key identifiers for 8M0057307 are 130°F and 3.0L V6 OptiMax. Several older Mercury thermostat numbers supersede to this current part, so matching the original number and engine serial range is the safest fitment check. A common question is whether this thermostat fits Pro XS or racing 3.0L/3.2L engines — those applications should be verified by serial number, as they may use the same current number through a different supersession path but have different installation requirements.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 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.