130°F (54°C) Thermostat for Mercury Mariner 200–250 HP 2.5L/3.0L DFI Engines – Replaces 885599004, 8M0057307
130°F (54°C) Thermostat for Mercury Mariner 200–250 HP 2.5L/3.0L DFI Engines – Replaces 885599004, 8M0057307 is backordered and will ship as soon as it is back in stock.
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130°F (54°C) Thermostat for Mercury Mariner 200–250 HP 2.5L/3.0L DF...
130°F (54°C) Thermostat for Mercury Mariner 200–250 HP 2.5L/3.0L DFI Engines – Replaces 885599004, 8M0057307 is backordered and will ship as soon as it is back in stock.
Product Details
This is an aftermarket replacement 130°F (54°C) thermostat for selected Mercury and Mariner 200, 225, and 250 HP outboard engines with 2.5L or 3.0L DFI and EFI applications. The thermostat helps regulate engine operating temperature by opening at the specified 130°F rating.
Company fitment information identifies this thermostat for selected Mercury and Mariner 200–250 HP applications, including 200 3.0L DFI DTS, 200 3.0L EFI, 200 DFI, 225 3.0L EFI, 225 3.0L EFI SeaPro, 225 3.0L DFI DTS, 225 DFI, 250 3.0L EFI, and 250 Long 3.0L EFI models. Confirm the complete engine model and serial number before ordering.
- 130°F (54°C) temperature rating.
- Replacement thermostat for selected Mercury and Mariner applications.
- Single thermostat supplied; this is not the two-thermostat and gasket kit.
- Gasket is not included unless separately specified for your application.
Part Number References
The following manufacturer and aftermarket references are associated with this thermostat. Part-number references do not replace model and serial-number verification.
| Brand | Part Number | Reference |
|---|---|---|
| Mercury | 885599003 | Manufacturer reference |
| Mercury | 885599004 | Manufacturer reference |
| Mercury | 8855991 | Manufacturer reference as listed |
| Mercury | 8M0057307 | Manufacturer reference |
| Sierra | 18-3535 | Aftermarket reference; 130°F thermostat |
Engine Compatibility
Fitment below follows the available Mercury and Mariner application information. Keep the engine model, displacement, application, and serial-number range together when checking compatibility.
| Brand | Engine application | Rated HP | Displacement | Application details | Serial-number condition |
|---|---|---|---|---|---|
| Mercury / Mariner | 200 3.0L DFI DTS | 200 | 3.0L | All; company-listed fitment | Verify against the engine serial number |
| Mercury / Mariner | 200 3.0L EFI | 200 | 3.0L | 2003 and up; OT750164 and up | OT750164 and up |
| Mercury / Mariner | 200 DFI | 200 | 2.5L/3.0L application listing | 1997 and up | OG386496 and up |
| Mercury / Mariner | 225 3.0L EFI | 225 | 3.0L | 1999 and up | OG760300 and up |
| Mercury / Mariner | 225 3.0L EFI SeaPro | 225 | 3.0L | 2004 and up | OT801000 and up |
| Mercury / Mariner | 225 3.0L DFI DTS | 225 | 3.0L | 2003 and up | OT599000 and up |
| Mercury / Mariner | 225 DFI | 225 | 2.5L/3.0L application listing | 1998 and up | OG590000 and up |
| Mercury / Mariner | 250 3.0L EFI | 250 | 3.0L | 1999 and up | OG760300 and up |
| Mercury / Mariner | 250 Long 3.0L EFI | 250 | 3.0L | Long-model application | OT861319 and up |
Important: The listed serial ranges are application conditions, not universal coverage for every engine with the same horsepower. Check the engine identification label and the original thermostat before installation.
Technical Specifications
- Product type
- Engine thermostat
- Temperature rating
- 130°F (54°C)
- Engine range
- Selected Mercury and Mariner 200–250 HP 2.5L/3.0L DFI and EFI applications
- Installation
- Replacement component; verify orientation and application before installation
- Gasket
- Not included
- Product configuration
- Single thermostat, not a complete thermostat-and-gasket kit
What’s in the Box
- 1 × 130°F (54°C) engine thermostat
A thermostat cover gasket is not included with this single thermostat. Replace the gasket when required by the engine service procedure.
Installation Notes
- Confirm the engine model, displacement, application, and serial number before beginning work.
- Disconnect the battery and allow the engine to cool completely.
- Follow the manufacturer service procedure to access the thermostat housing.
- Remove the old thermostat and inspect the housing, sealing surfaces, and cooling passages.
- Clean away old gasket material without damaging the mating surfaces.
- Install the thermostat in the correct orientation for the engine.
- Install a new gasket or seal if required by the application; no gasket is supplied with this listing.
- Reinstall the housing and tighten fasteners to the engine manufacturer’s specified torque.
- Restore the cooling system as directed by the service manual, then run the engine and check for leaks and proper temperature regulation.
Troubleshooting & FAQ
What does a thermostat do?
A thermostat controls coolant flow so the outboard can operate within its specified temperature range. This replacement is rated to open at 130°F (54°C).
Is this a thermostat kit?
No. The product is one thermostat only. It does not include the two thermostats and two cover gaskets associated with the separate 18-3606 thermostat kit.
Is a gasket included?
No. A thermostat cover gasket is not included. Use the gasket specified for your exact engine application and replace it during installation when required.
Does it fit every Mercury or Mariner 200–300 HP engine?
No. The documented fitment for this product is selected 200, 225, and 250 HP 2.5L/3.0L DFI and EFI applications. The available company fitment does not establish coverage for every 300 HP engine. Verify the complete model and serial number before purchase.
How can I confirm compatibility?
Compare the engine model, displacement, application type, serial-number range, and original thermostat reference with the information above. When any detail differs, consult the engine service manual or a qualified marine technician.
Is this an OEM part?
This listing is for an aftermarket replacement thermostat. Mercury and Sierra numbers shown on this page are reference numbers for identification and compatibility; the replacement is not represented as a genuine Mercury-branded component.
Safety & Important Information
- Use the manufacturer-specified thermostat temperature rating for the engine.
- Do not rely on horsepower alone to determine fitment; model, displacement, application, and serial number must also match.
- Allow the engine to cool before servicing the cooling system.
- Professional installation is recommended if the correct service procedure or torque specifications are unavailable.
About Sea Sierra
- Marine replacement parts selected for common service and repair applications.
- Clear part-number and fitment references to help support application matching.
- Practical replacement solutions for maintaining marine cooling systems.
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