Thermostat – Fits Honda Marine 8-225 HP (Replaces 19300-ZW9-003, 19300-ZY3-023)
Thermostat – Fits Honda Marine 8-225 HP (Replaces 19300-ZW9-003, 19300-ZY3-023) 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.
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Thermostat – Fits Honda Marine 8-225 HP (Replaces 19300-ZW9-003, 19...
Thermostat – Fits Honda Marine 8-225 HP (Replaces 19300-ZW9-003, 19300-ZY3-023) is backordered and will ship as soon as it is back in stock.
Product Details
This stainless steel Thermostat – Fits Honda Marine 8-225 HP (Replaces 19300-ZW9-003, 19300-ZY3-023) is engineered for Honda 4-stroke outboard engines from 8 HP to 225 HP (1998–present). It precisely regulates coolant flow to maintain optimal engine operating temperature, ensuring efficiency and protecting against overheating.
This part is a direct replacement for Honda part numbers 19300-ZW9-003 and 19300-ZY3-023, as well as Sierra equivalents 18-3628 and 18-3541.
- Designed for direct-fit installation on the engine mount.
- Constructed from corrosion-resistant stainless steel and copper.
- Features a heat- and oil-resistant NBR rubber seal for durability.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Honda | 19300-ZW9-003 |
| Honda | 19300-ZY3-023 |
| Honda | 19300ZY3023 |
| Honda | 19300ZW9003 |
| Sierra | 18-3628 |
| Sierra | 18-3541 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This thermostat fits a wide range of Honda Marine outboard engines produced from 1998 to the present day.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Honda | BF8D | 8 | 4-Stroke | 1998–Present | 19300-ZW9-003 | |
| Honda | BFP8D | 8 | 4-Stroke | 1998–Present | 19300-ZW9-003 | Power Thrust version |
| Honda | BF9.9D | 9.9 | 4-Stroke | 1998–Present | 19300-ZW9-003 | |
| Honda | BFP9.9D | 9.9 | 4-Stroke | 1998–Present | 19300-ZW9-003 | Power Thrust version |
| Honda | BF15D | 15 | 4-Stroke | 1998–Present | 19300-ZW9-003 | |
| Honda | BFP15D | 15 | 4-Stroke | 1998–Present | 19300-ZW9-003 | Power Thrust version |
| Honda | BF20D | 20 | 4-Stroke | 1998–Present | 19300-ZW9-003 | |
| Honda | BFP20D | 20 | 4-Stroke | 1998–Present | 19300-ZW9-003 | Power Thrust version |
| Honda | BF25D | 25 | 4-Stroke | 1998–Present | 19300-ZW9-003 | |
| Honda | BF30D | 30 | 4-Stroke | 1998–Present | 19300-ZW9-003 | |
| Honda | BF40A | 40 | 4-Stroke | 1998–Present | 19300-ZW9-003 | |
| Honda | BF40D | 40 | 4-Stroke | 1998–Present | 19300-ZW9-003 | |
| Honda | BF50A | 50 | 4-Stroke | 1998–Present | 19300-ZW9-003 | |
| Honda | BF50D | 50 | 4-Stroke | 1998–Present | 19300-ZW9-003 | |
| Honda | BF60A | 60 | 4-Stroke | 1998–Present | 19300-ZW9-003 | |
| Honda | BFP60A | 60 | 4-Stroke | 1998–Present | 19300-ZW9-003 | Power Thrust version |
| Honda | BF75D | 75 | 4-Stroke | 1998–Present | 19300-ZW9-003/19300-ZY3-023 | Alternative part number |
| Honda | BF90D | 90 | 4-Stroke | 1998–Present | 19300-ZW9-003/19300-ZY3-023 | Alternative part number |
| Honda | BF200A | 200 | 4-Stroke | 1998–Present | 19300-ZW9-003/19300-ZY3-023 | Alternative part number |
| Honda | BF225A | 225 | 4-Stroke | 1998–Present | 19300-ZW9-003/19300-ZY3-023 | Alternative part number |
Technical Specs
- Product Type
- Outboard Engine Thermostat
- Installation
- Engine Mount
- Fuel Type
- Gasoline
- Connection
- Direct Fit
- Housing Material
- Stainless Steel and Copper
- Housing Color
- Metallic Reddish-Brown
- Dimensions
- Top Gasket Diameter: 27.0 mm, Overall Length: 33.6 mm
- Weight
- 0.03 kg (1.09 oz)
- Fitting Type
- Direct Replacement
- Operating Temperature
- 60°C (140°F) Opening Temperature
- Warranty
- Standard Manufacturer Warranty
- Other Technical Attributes
- Features NBR rubber seal for heat resistance, corrosion resistance and oil resistance
What’s in the Box
- 1 x Thermostat (19300-ZW9-003)
- 2 x Thermostat Seals (19302-921-003)
Installation Notes
- Disconnect the battery and ensure the engine is completely cool.
- Place a drain pan under the thermostat housing and carefully drain the engine coolant.
- Locate and remove the bolts securing the thermostat housing cover.
- Remove the old thermostat and its seal. Note their orientation before removal.
- Thoroughly clean the mating surfaces of the housing and cover, removing all old gasket material and corrosion.
- Install the new thermostat and seal in the correct orientation.
- Re-secure the housing cover, tightening bolts to the manufacturer's specified torque.
- Refill the cooling system with the recommended coolant, checking for leaks.
- Reconnect the battery, start the engine, and let it reach operating temperature to ensure the thermostat opens correctly.
Troubleshooting & FAQ
How do I know if my thermostat is failing?
Common signs of a faulty thermostat include engine overheating (staying closed) or taking too long to reach operating temperature (staying open). You may notice alarms on your gauge or inconsistent engine performance.
What is the operating temperature of this thermostat?
This thermostat is designed to begin opening at 60°C (140°F) to allow coolant to circulate and maintain the engine's proper operating temperature.
What is the purpose of the included NBR rubber seal?
The Nitrile Butadiene Rubber (NBR) seal provides excellent resistance to engine oil, heat, and corrosion, ensuring a durable, long-lasting seal for the thermostat housing and preventing coolant leaks.
Is this part a guaranteed fit for my Honda BF75D?
Yes, this thermostat is listed as compatible with the Honda BF75D for model years 1998 to present. It directly replaces OEM part numbers 19300-ZW9-003 and 19300-ZY3-023. Always verify against your existing part before installation.
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.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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