Thermostat Housing Assembly for Mercury Mariner Outboards, 175–300 HP – Replaces 8M0137816, 8M0162139
Thermostat Housing Assembly for Mercury Mariner Outboards, 175–300 HP – Replaces 8M0137816, 8M0162139 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 Housing Assembly for Mercury Mariner Outboards, 175–300 ...
Thermostat Housing Assembly for Mercury Mariner Outboards, 175–300 HP – Replaces 8M0137816, 8M0162139 is backordered and will ship as soon as it is back in stock.
Product Details
This thermostat housing assembly is designed for Mercury and Mariner outboards rated from 175 to 300 HP. It helps maintain the engine cooling system's specified operating temperature of 140°F (60°C).
The assembly is listed for use with the Mercury reference numbers 8M0137816 and 8M0162139. Sierra reference 18-37816 is also associated with this application. Confirm the reference number and engine application before ordering.
- Thermostat housing assembly for Mercury Mariner outboards.
- Application range: 175–300 HP.
- Specified thermostat operating temperature: 140°F (60°C).
- Replacement reference numbers are provided for identification and cross-reference purposes.
Part Number Matrix
Use the following references to compare the replacement with the part being removed from your engine.
| Brand | Reference Number | Reference Type |
|---|---|---|
| Mercury | 8M0137816 | OEM reference |
| Mercury | 8M0162139 | OEM reference |
| Sierra | 18-37816 | Aftermarket reference |
Engine Compatibility
This assembly is cataloged for Mercury and Mariner outboards in the 175–300 HP range. Engine families and serial-number coverage can vary by model year and production configuration, so verify the original housing, reference number, and engine identification before installation.
| Brand | Application | Rated HP | Operating Temperature | Reference Numbers |
|---|---|---|---|---|
| Mercury / Mariner | Outboard thermostat housing assembly | 175–300 HP | 140°F (60°C) | 8M0137816, 8M0162139, Sierra 18-37816 |
Technical Specifications
- Product Type
- Thermostat housing assembly
- Brand Application
- Mercury and Mariner
- Horsepower Range
- 175–300 HP
- Operating Temperature
- 140°F (60°C)
- Installation
- Replacement installation; verify application before fitting
What’s in the Box
- 1 × thermostat housing assembly
Additional gaskets, seals, fasteners, or related cooling-system components are not confirmed as included unless specifically shown or listed with the supplied product.
Installation Notes
- Allow the engine to cool completely before beginning work.
- Disconnect the battery and follow the applicable Mercury service procedure for your engine.
- Identify the thermostat housing and note the orientation of the existing components before removal.
- Remove the housing carefully and inspect the mating surfaces for damage, corrosion, or old gasket material.
- Install the replacement assembly in the correct orientation using the required new seals or gaskets for your engine.
- Tighten fasteners to the engine manufacturer's specified torque; do not substitute a general torque value.
- Restore the cooling system as required, check for leaks, and verify proper operating temperature before returning the engine to service.
Troubleshooting & FAQ
What does this product replace?
This thermostat housing assembly is listed with Mercury reference numbers 8M0137816 and 8M0162139, plus Sierra reference 18-37816. Match the number on your original part before ordering.
What temperature is this thermostat application intended to maintain?
The specified operating temperature is 140°F (60°C).
Does this fit every Mercury or Mariner outboard?
No. The listed application is limited to Mercury and Mariner outboards in the 175–300 HP range. Model, year, and serial-number coverage may differ, so verify the original part and engine details before purchase.
Is this sold as a multi-piece kit?
No. This listing is for one thermostat housing assembly. Extra gaskets, seals, fasteners, or other cooling-system parts are not confirmed as included unless specifically shown or stated.
Can I install it without checking the service information?
Use the service procedure and torque specifications for the specific engine. Professional installation is recommended when the correct installation procedure or required sealing components are uncertain.
What should I check before ordering?
Compare the original housing, reference number, engine brand, horsepower rating, and available model or serial information. If any of these details do not match, confirm compatibility before purchasing.
Shipping speed & cost
Shipping options and delivery estimates are shown at checkout based on the destination and service selected.
Warranty & returns
Warranty and return eligibility are governed by the store's current policies. Contact support before installation if the part received does not match the ordered application.
Safety & Important Information
- Verify the reference number and engine application before ordering.
- Allow the engine to cool completely before servicing the cooling system.
- Use the manufacturer's service information for installation, sealing, and torque specifications.
- Do not operate the engine if coolant leaks or abnormal temperature behavior is observed after installation.
- Professional installation is recommended when application or installation requirements are uncertain.
About Sea Sierra
- Marine Parts Support — We provide application-focused replacement parts for marine engines and systems.
- Reference-Based Ordering — Product references and application details are provided to help you compare the replacement with your original part.
- Service-Focused Fulfillment — Contact support if you need help confirming the listed application before ordering.
Payment & Security
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