Thermostat with Housing Kit – Fits Mercury/Mariner Verado 135–300 HP (Replaces 892864T04, 8M0174561)
Thermostat with Housing Kit – Fits Mercury/Mariner Verado 135–300 HP (Replaces 892864T04, 8M0174561) is backordered and will ship as soon as it is back in stock.
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Thermostat with Housing Kit – Fits Mercury/Mariner Verado 135–300 H...
Thermostat with Housing Kit – Fits Mercury/Mariner Verado 135–300 HP (Replaces 892864T04, 8M0174561) is backordered and will ship as soon as it is back in stock.
Product Details
This Thermostat with Housing Kit is a direct-replacement cooling-system component for Mercury and Mariner Verado four-stroke outboard engines rated from 135 HP through 300 HP. It combines the thermostat and housing in one service assembly to help regulate coolant flow and maintain the engine's specified operating temperature.
The assembly is listed for Mercury part numbers 892864T04 and 8M0174561. Sierra reference 18-3631 is identified as a thermostat with housing for the same application family.
- Thermostat and housing assembly for Mercury/Mariner Verado applications.
- Rated opening temperature: 143°F (62°C).
- Direct replacement design for the listed OEM references.
- Confirm the engine horsepower, model, and serial number before ordering.
Part Number Matrix
Use the following references to compare the listed Mercury and Sierra numbers.
| Brand | Part Number | Description | Application Note |
|---|---|---|---|
| Mercury | 892864T04 | OEM reference | Replaced by or cross-referenced with 8M0174561 in the listed application. |
| Mercury | 8M0174561 | Thermostat assembly | Catalog occurrences include Verado 135–300 HP four-stroke models. |
| Sierra | 18-3631 | Thermostat with housing | Aftermarket cross-reference for the listed Mercury application. |
Engine & Model Compatibility
The company application range for this product is Mercury and Mariner Verado four-stroke outboards from 135 HP to 300 HP. Serial-number conditions remain important because the same horsepower can be divided into different catalog diagrams and serial ranges.
| Brand | Model Family | Rated HP | Stroke | Representative Serial Conditions | Reference |
|---|---|---|---|---|---|
| Mercury/Mariner | Verado L4 | 135 | 4-Stroke | Catalog occurrences include 0P419487 and later ranges, plus 1B227000-series and 1B517159-and-up ranges. | 8M0174561 |
| Mercury/Mariner | Verado L4 | 150 | 4-Stroke | Catalog occurrences include 0P419487 and later ranges, plus 1B227000-series and 1B517159-and-up ranges. | 8M0174561 |
| Mercury/Mariner | Verado L4 | 175 | 4-Stroke | Catalog occurrences include 0P419487 and later ranges, plus 1B227000-series and 1B517159-and-up ranges. | 8M0174561 |
| Mercury/Mariner | Verado L4 | 200 | 4-Stroke | Catalog occurrences include 0P514869-and-up, 1B517159-and-up, and 1B831000-and-up ranges. | 8M0174561 |
| Mercury/Mariner | Verado L6 | 200 | 4-Stroke | Catalog occurrences include 0T980000–1B226999, 1B227000-series, 1B517434-and-up, and Pro Verado serial ranges. | 8M0174561 |
| Mercury/Mariner | Verado L6 | 225 | 4-Stroke | Catalog occurrences include 0T980000–1B226999, 1B227000-series, 1B517434-and-up, and 2B144123-and-up ranges. | 8M0174561 |
| Mercury/Mariner | Verado L6 | 250 | 4-Stroke | Catalog occurrences include 0T980000–1B226999, 1B227000-series, 1B517434-and-up, and Pro Verado ranges. | 8M0174561 |
| Mercury/Mariner | Verado L6 | 275 | 4-Stroke | Catalog occurrences include 0T980000–1B226999, 1B227000-series, 1B517434-and-up, and 2B144123-and-up ranges. | 8M0174561 |
| Mercury/Mariner | Verado L6 | 300 | 4-Stroke | Catalog occurrences include 0P520553-and-up, 1B517434-and-up, and Pro Verado serial ranges. | 8M0174561 |
Technical Specifications
- Product Type
- Thermostat with housing assembly
- Application
- Mercury and Mariner Verado four-stroke outboards, 135–300 HP
- Opening Temperature
- 143°F (62°C) nominal
- Installation
- Direct replacement for the listed application
- OEM References
- 892864T04; 8M0174561
- Aftermarket Reference
- Sierra 18-3631
What's in the Box
- 1 × thermostat with housing assembly
Gaskets, O-rings, clamps, fasteners, or other installation hardware are not confirmed as included by the product record. Reuse or replacement of those items should be determined from the engine service procedure and the condition of the original parts.
Installation Notes
- Confirm the engine model, horsepower, stroke, and serial number before beginning work.
- Turn the engine off and allow it to cool completely. Follow the manufacturer's safety procedure and disconnect the battery when required.
- Remove the components and hoses necessary to access the thermostat housing.
- Remove the original assembly and clean the mounting and sealing surfaces without damaging them.
- Install the replacement thermostat with housing using the correct sealing components for your engine.
- Reconnect the hoses and hardware, tightening fasteners to the manufacturer's specified torque.
- Restore the cooling system as required by the service manual.
- Run the engine according to the manufacturer's procedure and check for leaks and abnormal temperature indications.
Troubleshooting & FAQ
What symptoms can indicate a thermostat problem?
Possible symptoms include overheating, an engine that runs colder than expected, unstable temperature readings, or coolant leakage around the thermostat housing.
How do I confirm fitment?
Match the engine brand, Verado model family, horsepower, four-stroke configuration, and serial number to the application information above. When the serial number is outside the listed conditions or cannot be identified, consult the engine service information before ordering.
Does this product fit 350 HP, 400 HP, or 400R Verado engines?
No fitment for 350 HP, 400 HP, or 400R engines is stated for this product record. This listing is limited to the company-specified 135–300 HP Verado range.
Is this an OEM Mercury part?
This listing is for a replacement thermostat with housing. The Mercury numbers 892864T04 and 8M0174561 are provided as OEM reference numbers; the replacement itself should not be represented as a genuine Mercury component.
What temperature is the thermostat rated for?
The listed nominal opening temperature is 143°F (62°C).
Safety & Important Information
- Work only on a completely cool engine and follow the applicable service-manual safety instructions.
- Verify the serial number and compare the original assembly with the replacement before installation.
- Do not assume that a similar-looking thermostat fits every Verado engine.
- Use the correct sealing components and installation torque for the specific engine.
About Sea Sierra
- Marine Parts Focus — Replacement components selected for practical marine service applications.
- Application-Focused Listings — Product references and fitment details are provided to help match the correct engine configuration.
- Service-Friendly Information — Clear part-number and installation notes support accurate maintenance planning.
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