140°F Thermostat & Gasket Kit – Fits Mercury Marine 8-35HP (Replaces 8M0119207, 855676002, 855676005)
140°F Thermostat & Gasket Kit – Fits Mercury Marine 8-35HP (Replaces 8M0119207, 855676002, 855676005) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
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140°F Thermostat & Gasket Kit – Fits Mercury Marine 8-35HP (Rep...
140°F Thermostat & Gasket Kit – Fits Mercury Marine 8-35HP (Replaces 8M0119207, 855676002, 855676005) is backordered and will ship as soon as it is back in stock.
Product Details
This 140°F Thermostat & Gasket Kit is an essential component for maintaining optimal engine temperature in Mercury Marine 4-Stroke outboards from 8–35HP (2002–Present), including Carbureted, EFI, Jet, and SeaPro models. It ensures your engine operates within the correct temperature range, preventing overheating and improving performance.
It serves as a direct replacement for multiple OEM and aftermarket parts, including Mercury 8M0119207, 855676002, 855676005, Sierra 18-43175, and Nissan/Tohatsu equivalents.
- Engineered for direct OEM-replacement fitment.
- Corrosion-resistant stainless steel housing for durability in marine environments.
- Kit includes thermostat, housing gasket, and rubber seal for a complete installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 8M0119207 |
| Mercury | 855676002 |
| Mercury | 855676005 |
| Sierra | 18-43175 |
| Nissan/Tohatsu | 3NV010300M |
| Tohatsu | 3R3-01030-0 |
| Tohatsu | 3R3010300M |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury Marine models, check your engine's serial number (S/N) to ensure it falls within the specified range for a guaranteed fit. This thermostat fits a wide variety of 4-stroke models from 2002 to present.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | Outboard | 8 | 4-Stroke | 2002–Up (S/N 0P325500 & Up) | 855676002/8M0119207 | CYLINDER BLOCK |
| Mercury | Outboard | 8 | 4-Stroke | 2002–Up (S/N 0R042475 & Up) | 855676002/8M0119207 | CYLINDER BLOCK |
| Mercury | Outboard | 9.9 | 4-Stroke | 2002–Up (S/N 0R042475 & Up) | 855676002/8M0119207 | CYLINDER BLOCK |
| Mercury | Outboard | 10 | 4-Stroke | 2005–Up (S/N 0R575531 THRU 0R833819) | 855676002/8M0119207 | CYLINDER BLOCK |
| Mercury | Outboard | 15 | 4-Stroke | Carb 2CYL (S/N 0R235949 THRU 0R833819) | 855676002/8M0119207 | Cat.# 90-898103160 |
| Mercury | Outboard | 15 | 4-Stroke | Carb 2CYL JCI (S/N 0R558208 THRU 0R833819) | 855676002/8M0119207 | Cat.# 90-898103160 |
| Mercury | Outboard | 15 | 4-Stroke | SEAPRO (S/N 0R051685 THRU 0R123564) | 855676002/8M0119207 | Cat.# 90-895256005 |
| Mercury | Outboard | 15 | 4-Stroke | SEAPRO (S/N 0R123565 & Up) | 855676002/8M0119207 | Cat.# 90-895256006 |
| Mercury | Outboard | 20 | 4-Stroke | Carb (S/N 0R235168 THRU 0R833819) | 855676002/8M0119207 | Cat.# 90-898103160 |
| Mercury | Outboard | 25 | 4-Stroke | SEAPRO (S/N 0R051710 & Up) | 855676002/8M0119207 | Cat.# 90-895257005 |
| Mercury | Outboard | 25 | 4-Stroke | EFI 3CYL (S/N 0R106999 & Up - USA) | 855676002/8M0119207 | Cat.# 90-898126006 |
| Mercury | Outboard | 25 | 4-Stroke | Jet EFI 3CYL (S/N 0R165086 & Up - USA) | 855676002/8M0119207 | Cat.# 90-898126006 |
| Mercury | Outboard | 30 | 4-Stroke | EFI 3CYL (S/N 0R106999 & Up - USA) | 855676002/8M0119207 | Cat.# 90-898126006 |
| Mercury | Outboard | 35 | 4-Stroke | EFI | 855676002/8M0119207 | Verified from multiple sources |
Technical Specs
- Product Type
- Engine Thermostat with Gasket Kit
- Installation
- Direct OEM Replacement
- Temperature Rating
- 60°C/140°F
- Application
- Marine Outboard Engine Cooling System
- Housing Material
- Stainless Steel (Corrosion Resistant)
- Package Includes
- Thermostat, Gaskets, Rubber Seal
- Other Technical Attributes
- Self-cleaning design allows cooling system contaminants to flush through closing surfaces
What’s in the Box
- 1 x Thermostat (855676002/8M0119207)
- 1 x Thermostat Rubber Seal
- 1 x Thermostat Housing Gasket (27-853702005/27-898101194)
Installation Notes
- Ensure the engine is completely cool before starting. Disconnect the battery for safety.
- Locate the thermostat housing on the engine block. It is typically a small dome-shaped cover held by two or three bolts.
- Place a catch pan underneath to collect any residual coolant that may spill.
- Remove the bolts securing the housing cover. You may need to gently tap the cover to break the gasket seal.
- Note the orientation of the old thermostat before removing it. Lift it out, followed by the old gasket and seal.
- Clean both the housing and the cover surfaces thoroughly, removing all traces of the old gasket material.
- Install the new gasket, thermostat, and rubber seal in the reverse order of removal. Ensure the thermostat is oriented correctly.
- Replace the housing cover and tighten the bolts to the manufacturer's recommended torque specification. Do not overtighten.
- Reconnect the battery, start the engine, and check for any leaks around the housing as the engine warms up.
Troubleshooting & FAQ
How do I know if my thermostat is failing?
Common signs of a faulty thermostat include engine overheating alarms, the engine running colder than usual (not reaching operating temperature), or sudden fluctuations in the temperature gauge. A thermostat stuck open will prevent the engine from warming up, while one stuck closed will cause it to overheat.
Is this thermostat the correct temperature for my engine?
This is a 140°F (60°C) thermostat. This rating is specified by the OEM for the listed Mercury engine models to ensure optimal performance, fuel efficiency, and engine longevity. Using a thermostat with a different temperature rating can negatively affect your engine.
Can I replace just the thermostat without the gaskets?
It is strongly recommended to replace the gaskets and seals whenever the thermostat is replaced. Old gaskets can become brittle and may not seal properly when reassembled, leading to coolant leaks. This kit includes all necessary components for a complete and reliable installation.
What is the benefit of a "self-cleaning" design?
The self-cleaning feature refers to small design elements that allow sediment, salt, and other contaminants in the cooling water to pass through the thermostat rather than getting trapped. This helps prevent the thermostat from sticking and ensures more reliable operation over time, especially in saltwater.
How often should an outboard thermostat be replaced?
Thermostats don't have a strict replacement interval, but they are a common wear item. Many technicians recommend inspecting or replacing them every 2-3 years as part of routine cooling system maintenance, or immediately if you experience any symptoms of failure.
What's the difference between an OEM and an aftermarket part?
This listing is for an aftermarket replacement, not an original equipment manufacturer (OEM) part. It is built to OEM-level specifications with comparable materials in an ISO 9002 facility and is batch-inspected for consistency and quality.
What are your shipping speeds and costs?
We ship worldwide quickly, with a typical transit time of 5–15 days for most regions. Standard shipping is free. If available for your location, expedited shipping options and their costs will be presented at checkout.
What is the warranty and return policy?
This part is covered by a 1-year warranty against manufacturing defects under normal marine use. If you encounter any issues, please contact our support team with your order details. Returns are accepted within our standard window for items that are unused and in their original condition. See our policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part before purchase. If anything differs—even if your model appears on a compatibility list—do not purchase.
- This is an aftermarket replacement part, not an OEM component.
- Professional installation is highly recommended for safety and optimal performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
- Fast Global Fulfillment — We offer free standard delivery to most regions with an average transit time of 5–15 days.
- Manufacturer-Direct Value — Our direct-sourcing model allows us to provide fair pricing without compromising on materials or quality control.
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