Thermostat Service Kit – Fits Mercury/Mariner 6–25 HP 2-Stroke Outboards, Replaces 14586A3
Thermostat Service Kit – Fits Mercury/Mariner 6–25 HP 2-Stroke Outboards, Replaces 14586A3 is backordered and will ship as soon as it is back in stock.
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Thermostat Service Kit – Fits Mercury/Mariner 6–25 HP 2-Stroke Outb...
Thermostat Service Kit – Fits Mercury/Mariner 6–25 HP 2-Stroke Outboards, Replaces 14586A3 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket thermostat service kit is designed for Mercury and Mariner 2-stroke outboard engines rated from 6 to 25 HP. The supplier specification lists a nominal thermostat operating temperature of 122°F (50°C).
The kit is intended as a service replacement for the Mercury Marine reference number 14586A3. Other supplier-listed reference numbers include Mercury 14586A4, 14586A5, 14586A6, 14586A7, 75962A9, 75962A10, and 75962A11, plus Sierra 18-43052. These numbers are provided for identification and cross-referencing; always verify the engine serial number and the original component before ordering.
- For Mercury and Mariner 2-stroke outboards from 6–25 HP.
- 122°F (50°C) thermostat specification.
- Service-kit format for cooling-system maintenance.
- Aftermarket replacement; not a genuine Mercury Marine component.
Part Number Matrix
The following references are associated with this application in the available supplier and catalog data.
| Brand | Reference Number | Use |
|---|---|---|
| Mercury Marine | 14586A3 | Primary replacement reference |
| Mercury Marine | 14586A4, 14586A5, 14586A6, 14586A7 | Supplier-listed Mercury references; verify configuration |
| Mercury Marine | 75962A9, 75962A10, 75962A11 | Cross-reference numbers reported for this application |
| Sierra | 18-43052 | Aftermarket thermostat-kit reference |
| GLM | 13121 | Catalog cross-reference; verify kit contents and application |
| Mallory | 9-79805 | Catalog cross-reference; verify kit contents and application |
Engine & Model Compatibility
Application coverage is Mercury/Mariner 6–25 HP, 2-stroke outboard engines. Because Mercury and Mariner applications can vary by model configuration and serial-number range, match the complete engine identification before installation.
| Brand | Horsepower | Stroke | Application | Verification Required |
|---|---|---|---|---|
| Mercury / Mariner | 6–25 HP | 2-Stroke | Small outboard cooling systems | Confirm exact model and serial number |
| Mercury / Mariner | 6–25 HP | 2-Stroke | Model families may include Sea Pro, Marathon, Viking, XR and related configurations | Do not rely on horsepower alone; verify the original thermostat and reference number |
Important: The available supplier record confirms the 6–25 HP 2-stroke range but does not provide a complete model-year or serial-number chart. Check the engine service manual or parts diagram before purchase.
Technical Specifications
- Product Type
- Thermostat service kit
- Thermostat Rating
- 122°F (50°C)
- Application
- Marine outboard cooling system
- Compatible Engines
- Mercury and Mariner 6–25 HP 2-stroke outboards
- Primary Reference
- Mercury Marine 14586A3
- Aftermarket Reference
- Sierra 18-43052
- Installation
- Replacement service installation; follow the engine service manual
- Brand Status
- Aftermarket replacement, not OEM
What’s in the Box
This listing is supplied as a thermostat service kit for the stated Mercury/Mariner application. The available company record does not provide a verified item-by-item component list or fixed quantity for every seal, gasket, or accessory. Compare the kit contents with the original parts and the engine service-manual requirements before installation.
Installation Notes
Always allow the engine to cool completely and consult the correct service manual before beginning work. A qualified marine technician should perform the repair when the model, serial range, or cooling-system configuration is uncertain.
- Confirm the engine model, serial number, thermostat reference, and replacement temperature rating.
- Shut down the engine, disconnect the battery where applicable, and allow the powerhead to cool.
- Remove the thermostat housing or cover according to the service-manual procedure.
- Remove the old thermostat and sealing components, noting their orientation and installation order.
- Clean the mating surfaces without damaging the housing or cylinder-head sealing area.
- Install the replacement thermostat and the required service seals or gaskets in the specified orientation.
- Reinstall the housing and tighten fasteners to the manufacturer's specified torque.
- Start the engine using the proper water-supply procedure and check for leaks and normal cooling-water flow.
- Verify that the engine reaches its normal operating temperature without overheating.
Troubleshooting & FAQ
How do I confirm that this kit fits my engine?
Confirm all of the following: Mercury or Mariner brand, 6–25 HP rating, 2-stroke configuration, engine model, serial number, and the original thermostat or reference number. Horsepower alone is not sufficient to guarantee fitment.
What thermostat temperature is specified for this kit?
The supplier specification lists 122°F (50°C). Do not substitute a different temperature rating unless it is specifically approved for your engine configuration.
What symptoms can indicate a thermostat problem?
Possible symptoms include overheating, unusually cold running, unstable operating temperature, reduced cooling-water control, or a temperature warning. Other cooling-system faults can cause similar symptoms, so inspect the water passages, water pump, passages, and sensors as required.
Is this an OEM Mercury Marine part?
No. This is an aftermarket replacement service kit. Mercury, Mariner, Sierra, GLM, and Mallory reference numbers are used only to help identify the intended application and should not be interpreted as an OEM-brand claim for this product.
Does the package include every poppet-valve component?
The available company record does not confirm a complete poppet-valve component set or a fixed item-by-item package list. Verify the actual kit contents before beginning a repair that requires additional poppet-valve parts.
Safety & Important Information
- Verify the engine model, serial number, thermostat rating, and reference number before ordering.
- Do not install a thermostat with a different temperature rating unless the engine manufacturer specifies it.
- Use the service manual for torque values, seal orientation, and cooling-system procedures.
- This is an aftermarket replacement and is not manufactured or branded as a genuine Mercury Marine component.
- Professional installation is recommended when the engine's configuration or cooling-system condition is uncertain.
About Sea Sierra
- Marine Application Focus — Parts are listed for specific outboard service applications.
- Clear Cross-Referencing — Manufacturer and aftermarket reference numbers are provided to support identification.
- Service-Minded Support — Match the engine model, serial number, and original component before installation.
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