Honda Marine Outboard Thermostat, 125°F/52°C – Fits BF5A, BF8A, BF9.9, BF15A, BF50F, BF75E/F and BF100E/F (Replaces 19300-881-761, Sierra 18-3627)
Honda Marine Outboard Thermostat, 125°F/52°C – Fits BF5A, BF8A, BF9.9, BF15A, BF50F, BF75E/F and BF100E/F (Replaces 19300-881-761, Sierra 18-3627) is backordered and will ship as soon as it is back in stock.
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Honda Marine Outboard Thermostat, 125°F/52°C – Fits BF5A, BF8A, BF9...
Honda Marine Outboard Thermostat, 125°F/52°C – Fits BF5A, BF8A, BF9.9, BF15A, BF50F, BF75E/F and BF100E/F (Replaces 19300-881-761, Sierra 18-3627) is backordered and will ship as soon as it is back in stock.
Product Details
This Honda Marine outboard thermostat is a replacement thermostat designed for the Honda BF-series models listed below. It is specified to maintain an operating temperature of 125°F/52°C and replaces Honda reference 19300-881-761.
The thermostat is also cross-referenced with Sierra 18-3627. Use the model information and part-number references below to verify compatibility before ordering.
- Replacement thermostat for selected Honda marine outboard engines.
- Specified operating temperature: 125°F/52°C.
- Designed for installation in the engine thermostat or cylinder-head cooling-system application, depending on model.
- This listing is for the thermostat itself; gaskets, seals, bolts and other installation hardware are not included unless separately stated by the seller.
Part Number Matrix
These are the documented manufacturer and aftermarket reference numbers associated with this thermostat.
| Brand | Part Number | Reference Type |
|---|---|---|
| Honda | 19300-881-761 | OEM reference |
| Sierra | 18-3627 | Aftermarket cross-reference |
Engine & Model Compatibility
The company fitment record identifies the following Honda BF-series models for this thermostat. Model suffixes and serial-number conditions can affect fitment, so compare the original thermostat and the engine service-manual application before installation.
| Brand | Compatible Model | Engine Type | OEM Reference |
|---|---|---|---|
| Honda | BF5A1, BF5A2, BF5A3, BF5A4, BF5A5, BF5A6, BF5AH, BF5AK, BF5AK0, BF5AM, BF5AW, BF5AX, BF5AY | BF-series marine outboard | 19300-881-761 |
| Honda | BF8A3, BF8A4, BF8A5, BF8A6, BF8AH, BF8AK, BF8AK0, BF8AM, BF8AW, BF8AX, BF8AY | BF-series marine outboard | 19300-881-761 |
| Honda | BF9.9AH, BF9.9AK, BF9.9AM, BF9.9AW, BF9.9AX, BF9.9AY | BF-series marine outboard | 19300-881-761 |
| Honda | BF15A1, BF15A2, BF15AH, BF15AK, BF15AM, BF15AW, BF15AX, BF15AY | BF-series marine outboard | 19300-881-761 |
| Honda | BF50F | BF-series marine outboard | 19300-881-761 |
| Honda | BF75E, BF75F | BF-series marine outboard | 19300-881-761 |
| Honda | BF100E, BF100F | BF-series marine outboard | 19300-881-761 |
Technical Specs
- Product Type
- Marine outboard engine thermostat
- Application
- Selected Honda BF-series outboard engines
- Operating Temperature
- 125°F/52°C
- Installation
- Replacement thermostat in the model-specific thermostat or cooling-system application
- Honda Reference
- 19300-881-761
- Sierra Reference
- 18-3627
What’s in the Box
- 1 x Replacement thermostat
Note: The matching company product record identifies this product as a single thermostat rather than a multi-piece kit. Gaskets, rubber seal rings and other installation parts are not included in this listing unless specifically shown or stated with the order.
Installation Notes
- Confirm the engine model, suffix and existing thermostat reference before beginning work.
- Turn the engine off and allow it to cool completely. Follow the engine manufacturer's safety instructions.
- Locate the thermostat according to the service manual for the specific Honda BF model.
- Remove the thermostat cover or related retaining components carefully, preserving the orientation of the original thermostat.
- Remove the old thermostat and inspect the cover, sealing surfaces and related hardware for corrosion or damage.
- Clean the mating surfaces without scratching them. Replace any gasket or seal that the service manual identifies as non-reusable; replacement gaskets are not included with this thermostat.
- Install the new thermostat in the correct orientation and reassemble the cover using the manufacturer's specified torque.
- Run the engine according to the service procedure and check for leaks and correct cooling-system operation.
Installation procedures and required seals vary by model. Consult the appropriate Honda service manual or use a qualified marine technician when required.
Troubleshooting & FAQ
How do I confirm that this thermostat fits my Honda outboard?
Match your complete engine model and suffix against the compatibility table, then compare the original part number with Honda reference 19300-881-761 or the Sierra cross-reference 18-3627. If the model suffix or serial range differs, consult the engine service manual before ordering.
What are common signs of a failing thermostat?
A faulty thermostat may contribute to overheating, delayed warm-up, operation below the intended temperature or unstable temperature behavior. Cooling-system restrictions and other faults can produce similar symptoms, so inspect the complete system before replacing parts.
What is the thermostat operating temperature?
The product record specifies an operating temperature of 125°F/52°C.
Does this listing include a gasket or rubber seals?
No. This listing is for one thermostat. Gaskets, rubber seal rings and other installation hardware are not included unless specifically stated in the order details.
Can I install this thermostat myself?
Installation may be straightforward for an experienced marine mechanic, but the correct procedure, orientation, sealing method and torque specifications vary by engine model. Use the applicable service manual or seek professional installation.
Is this an OEM Honda thermostat?
This listing is a replacement product referenced against Honda part number 19300-881-761 and Sierra 18-3627. It is not presented as a genuine Honda-branded part.
What should I check before installation?
Verify the complete engine model and suffix, compare the original thermostat and reference number, inspect the thermostat cover and sealing surfaces, and obtain any model-specific gasket or seal required for reassembly.
Safety & Important Info
- Work only on a completely cool engine and follow all applicable marine-engine safety procedures.
- Verify the model, suffix and part reference before purchase; similar Honda BF models may use different cooling-system parts.
- Do not operate the engine if the thermostat cover leaks or if the cooling system does not function correctly after installation.
- This product listing is for one replacement thermostat and does not include a gasket, seal ring or other hardware unless separately specified.
About Sea Sierra
- Marine Parts Focus — We supply replacement components for outboard maintenance and repair applications.
- Fitment-Focused Listings — Product pages provide documented model and part-number references to help customers compare replacement parts.
- Support for Installation Planning — Always confirm the complete engine model and consult the applicable service information before beginning repairs.
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