Thermostat Housing with O-Ring Kit – Fits Mercury Marine Verado 135-400 HP (Replaces 892864T04/8M0174561)
Thermostat Housing with O-Ring Kit – Fits Mercury Marine Verado 135-400 HP (Replaces 892864T04/8M0174561) is backordered and will ship as soon as it is back in stock.
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Thermostat Housing with O-Ring Kit – Fits Mercury Marine Verado 135...
Thermostat Housing with O-Ring Kit – Fits Mercury Marine Verado 135-400 HP (Replaces 892864T04/8M0174561) is backordered and will ship as soon as it is back in stock.
Product Details
This Thermostat Housing with O-Ring Kit is a complete assembly designed for a wide range of Mercury Marine Verado engines. It ensures your engine maintains the correct operating temperature for optimal performance and longevity, fitting L4 and L6 Verado models from 135 HP to 400 HP, manufactured from 2004 to the present.
It serves as a direct replacement for Mercury part numbers 892864T04 and 8M0174561, as well as Sierra interchanges 18-3631 and 18-3631-K.
- Engineered for direct OEM-replacement installation.
- The kit includes the thermostat, housing, and necessary O-ring.
- Features a durable metal alloy housing and a brass thermostat mechanism.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury | 892864T04 | Superseded by 8M0174561 |
| Mercury | 8M0174561 | Current OEM Part |
| Sierra | 18-3631 | Interchangeable part |
| Sierra | 18-3631-K | Interchangeable kit |
| Aftermarket | REC892864T04 | Interchangeable part |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This part is designed exclusively for Mercury Marine Verado engines. Please check your serial number to ensure precise fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | Verado L4 | 135 | 4-Stroke | 2004–Present (1B227000-2B576734) | 892864T04/8M0174561 | 4-cylinder models |
| Mercury | Verado L4 | 150 | 4-Stroke | 2004–Present (1B227000-2B576734) | 892864T04/8M0174561 | 4-cylinder models |
| Mercury | Verado L4 | 175 | 4-Stroke | 2004–Present (1B227000-2B576734) | 892864T04/8M0174561 | 4-cylinder models |
| Mercury | Verado L4 | 200 | 4-Stroke | 2004–Present (1B517159-2B576734) | 892864T04/8M0174561 | 4-cylinder models |
| Mercury | Verado L6 | 200 | 4-Stroke | 2004–Present (0T980000-2B578935) | 892864T04/8M0174561 | 6-cylinder models |
| Mercury | Verado L6 Pro | 200 | 4-Stroke | 2004–Present (2B034840-2B577715) | 892864T04/8M0174561 | Pro 6-cylinder models |
| Mercury | Verado L6 | 225 | 4-Stroke | 2004–Present (0T980000-2B578935) | 892864T04/8M0174561 | 6-cylinder models |
| Mercury | Verado L6 | 250 | 4-Stroke | 2004–Present (0T980000-2B578935) | 892864T04/8M0174561 | 6-cylinder models |
| Mercury | Verado L6 Pro | 250 | 4-Stroke | 2004–Present (1B830170-2B577715) | 892864T04/8M0174561 | Pro 6-cylinder models |
| Mercury | Verado L6 | 275 | 4-Stroke | 2004–Present (0T980000-2B578935) | 892864T04/8M0174561 | 6-cylinder models |
| Mercury | Verado L6 | 300 | 4-Stroke | 2004–Present (1B517434-2B578935) | 892864T04/8M0174561 | 6-cylinder models |
| Mercury | Verado L6 Pro | 300 | 4-Stroke | 2004–Present (1B830170-2B577715) | 892864T04/8M0174561 | Pro 6-cylinder models |
| Mercury | Verado L6 Pro | 350 | 4-Stroke | 2015–Present (2B141124-3B342962) | 892864T04/8M0174561 | 2.6L L6 Pro models |
| Mercury | Verado L6 | 350 | 4-Stroke | 2015–Present (2B141617-3B342962) | 892864T04/8M0174561 | 2.6L L6 models |
| Mercury | Verado L6 | 400 | 4-Stroke | 2016–Present (2B618256-3B342962) | 892864T04/8M0174561 | 2.6L L6 models |
| Mercury | Racing L6 | 400R | 4-Stroke | 2015–Present (2B141124-3B342962) | 892864T04/8M0174561 | 2.6L L6 Racing models |
Technical Specs
- Product Type
- Thermostat Housing Assembly
- Installation
- Direct OEM replacement
- Temperature Rating
- 140°F (60°C)
- Housing Material
- Metal alloy with brass thermostat mechanism
- Connection
- Hose connection with clamp
- Operating Temperature
- Standard marine operating range
- Other Technical Attributes
- Includes thermostat, housing, and necessary O-ring
- Warranty
- Manufacturer warranty varies by brand (Mercury OEM: 1 year)
What’s in the Box
- 1 x Thermostat with Housing Assembly (892864T04/8M0174561)
- 1 x O-Ring seal (8M005958)
- 1 x Oetiker Clamp (888988008) - included with some kits
Installation Notes
- Always allow the engine to cool completely before starting work.
- Disconnect the boat's battery for safety.
- Drain the engine coolant into a suitable container.
- Locate the thermostat housing and carefully disconnect the attached hoses.
- Unbolt and remove the old thermostat housing assembly. Note the orientation of the old part.
- Thoroughly clean the mating surface on the engine block, removing any old gasket or sealant material.
- Install the new O-ring and place the new thermostat assembly into position.
- Tighten the mounting bolts to the manufacturer-specified torque in a crisscross pattern.
- Reconnect the hoses and secure them with clamps.
- Refill the cooling system with the appropriate coolant.
- Reconnect the battery, start the engine, and carefully check for leaks as it comes up to temperature.
Troubleshooting & FAQ
How do I know if my thermostat is failing?
Signs of a failing thermostat include the engine overheating, the temperature gauge reading unusually low, erratic temperature fluctuations, and potential coolant leaks around the housing. These symptoms indicate the thermostat is stuck open or closed.
What is the purpose of the 140°F temperature rating?
The 140°F (60°C) rating is the temperature at which the thermostat begins to open, allowing coolant to circulate through the engine. This helps the engine warm up quickly and then maintains a stable operating temperature for optimal efficiency and performance.
Is the O-ring included necessary for installation?
Yes, the included O-ring is critical for creating a proper seal between the thermostat housing and the engine. Never reuse an old O-ring, as it can lead to coolant leaks and overheating.
Is this part compatible with non-Verado Mercury engines?
No, this specific thermostat kit is designed exclusively for the Mercury Verado L4 & L6 engine family. Using it on other models will likely result in improper fitment and engine cooling issues. Always check the compatibility table.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
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