Thermostat Kit for Mercury/Mariner 6–25 HP 2-Stroke Outboards – Replaces OEM 14586A3
Thermostat Kit for Mercury/Mariner 6–25 HP 2-Stroke Outboards – Replaces OEM 14586A3 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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Thermostat Kit for Mercury/Mariner 6–25 HP 2-Stroke Outboards – Rep...
Thermostat Kit for Mercury/Mariner 6–25 HP 2-Stroke Outboards – Replaces OEM 14586A3 is backordered and will ship as soon as it is back in stock.
Product Details
This 120°F thermostat kit is designed for selected Mercury and Mariner 6–25 HP 2-stroke outboard motors. It helps the cooling system maintain the engine’s intended operating temperature and provides the thermostat and sealing components needed for a thermostat service.
The kit is documented as a replacement for Mercury Marine OEM thermostat reference 14586A3. Confirm the OEM number and engine application before ordering, particularly when working with older outboards or models outside the 6–25 HP 2-stroke range.
- 120°F nominal thermostat specification.
- Service kit for selected Mercury and Mariner 2-stroke outboards.
- Includes a thermostat and associated gaskets/sealing components for installation.
- Aftermarket replacement; Mercury Marine and Mariner are referenced for compatibility identification only.
Part Number Matrix
The following numbers are manufacturer or aftermarket reference numbers associated with this thermostat application. They are provided for identification and cross-reference purposes; verify the exact application before purchase.
| Brand | Reference Number | Reference Type |
|---|---|---|
| Mercury Marine | 14586A3 | OEM reference |
| Mercury Marine | 75962A9 | OEM reference |
| Mercury Marine | 75962A10 | OEM reference |
| Mercury Marine | 75962A11 | OEM reference |
| Sierra | 18-43052 | Aftermarket reference |
Engine Compatibility
Catalog documentation identifies this thermostat kit for Mercury 6–25 HP 2-stroke outboard applications. The available evidence does not establish one universal year, model-name, or serial-number range for every engine in this horsepower group, so use the OEM reference and your engine’s complete model and serial information to confirm fitment.
| Brand | Horsepower Range | Stroke | Application Condition | OEM Reference |
|---|---|---|---|---|
| Mercury | 6–25 HP | 2-Stroke | Selected outboard applications; verify complete model and serial information | 14586A3 |
| Mariner | 6–25 HP | 2-Stroke | Selected outboard applications; verify complete model and serial information | 14586A3 |
Technical Specifications
- Product Type
- Thermostat service kit
- Thermostat Rating
- 120°F nominal
- Application
- Selected Mercury and Mariner 6–25 HP 2-stroke outboards
- Installation
- Replacement service part; installation should follow the applicable service manual
- Product Construction
- Aftermarket replacement thermostat with associated sealing components
What’s in the Box
- 1 × 120°F thermostat
- Thermostat seal or ring
- Thermostat cover gasket
- Additional thermostat gasket or sealing components included for the applicable kit configuration
Kit component appearance and exact gasket configuration may vary by application. Compare the existing thermostat housing and gasket arrangement before installation.
Installation Notes
- Allow the engine to cool completely, switch it off, and remove the engine-starting power connection as appropriate for your boat.
- Locate the thermostat housing and place suitable protection below the work area.
- Remove the housing cover and retain the fasteners in their original positions.
- Remove the old thermostat, seal, and gasket material. Clean the mating surfaces without damaging the housing.
- Install the replacement thermostat and sealing components in the same orientation as the original parts and as specified by the service manual.
- Reinstall the housing cover and tighten the fasteners to the manufacturer’s specification.
- Run the engine according to the service procedure, check for leaks, and confirm normal cooling-water flow and temperature behavior before returning the boat to service.
Troubleshooting & FAQ
What engines does this thermostat kit fit?
Catalog documentation identifies the application as selected Mercury and Mariner 6–25 HP 2-stroke outboards. Because model years and serial ranges can vary, verify the complete engine model, serial number, and OEM reference 14586A3 before ordering.
What temperature is this thermostat?
This is a 120°F nominal thermostat kit.
Is this an OEM Mercury part?
No. This is an aftermarket replacement kit. Mercury Marine and Mariner references are supplied only to identify the intended application and compatible reference numbers.
Does the kit include gaskets?
Yes. The kit includes the thermostat and associated sealing components, including gasket or seal components for the applicable thermostat housing configuration. Compare the included parts with the original installation before beginning the repair.
Can this be used on a 4-stroke engine?
This listing is documented for selected 2-stroke applications. Do not assume compatibility with a 4-stroke model unless its complete model information and OEM reference specifically confirm it.
What are common signs of a thermostat problem?
Possible symptoms include abnormal operating temperature, overheating, running colder than expected, inconsistent temperature behavior, or leakage around the thermostat housing. Diagnose the complete cooling system before replacing the thermostat.
Can I install it myself?
Thermostat replacement may be suitable for an experienced technician or mechanically skilled owner. Follow the correct service manual, use the specified tightening procedure, and seek professional assistance if the housing, fasteners, or cooling system are damaged.
Safety & Important Information
- Verify the engine brand, horsepower, stroke, complete model information, serial number, and OEM reference before purchase.
- Never work on a hot engine or pressurized cooling system.
- Use the applicable manufacturer service procedure for gasket orientation, seal placement, and fastener tightening.
- This is an aftermarket replacement and is not manufactured by Mercury Marine or Mariner.
About Sea Sierra
- Marine Replacement Parts — Practical replacement components for service and repair applications.
- Application-Focused Listings — Reference numbers and fitment conditions are provided to help match the correct part.
- Service-Ready Solutions — Components selected for common marine maintenance requirements.
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