Sierra 18-8900 Water Pump Impeller for Mercury Mariner 40–60 HP Outboards – Replaces Mercury 47-19453T, 47-19453
Sierra 18-8900 Water Pump Impeller for Mercury Mariner 40–60 HP Outboards – Replaces Mercury 47-19453T, 47-19453 is backordered and will ship as soon as it is back in stock.
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Sierra 18-8900 Water Pump Impeller for Mercury Mariner 40–60 HP Out...
Sierra 18-8900 Water Pump Impeller for Mercury Mariner 40–60 HP Outboards – Replaces Mercury 47-19453T, 47-19453 is backordered and will ship as soon as it is back in stock.
Product Details
The Sierra 18-8900 water pump impeller is an aftermarket replacement for selected Mercury and Mariner outboard cooling systems. It is listed for Mercury/Mariner 2-stroke 50, 55, and 60 HP applications, as well as selected 4-stroke 40–60 HP engines. The correct fit depends on the engine model, stroke type, and serial-number range, so verify those details before ordering.
This impeller replaces Mercury Marine OEM references 47-19453T and 47-19453. Mallory reference 9-45301 is also associated with this replacement application.
- Product type: Water pump impeller
- Brand reference: Sierra 18-8900
- Application: Selected Mercury and Mariner 2-stroke and 4-stroke outboards
- Installation: Direct replacement when the OEM number and engine specifications match
- Design: High-volume, long-vane impeller design for the outboard water-pump system
Part Number Matrix
Use these references to compare the impeller with the part currently installed on your engine or listed in the service manual. Part-number matching should be confirmed together with the engine model and serial number.
| Brand | Part Number | Reference Type |
|---|---|---|
| Sierra | 18-8900 | Aftermarket replacement number |
| Mercury Marine | 47-19453T | OEM reference |
| Mercury Marine | 47-19453 | OEM reference |
| Mallory | 9-45301 | Aftermarket reference |
| Mallory | 9-45301-10 | Catalog reference; confirm before ordering |
Engine & Model Compatibility
The company application data identifies this impeller for the following Mercury/Mariner engine groups. Serial-number ranges are included where the engine catalog provides them. Do not treat a horsepower match alone as confirmation of fitment.
| Brand | Model or Engine Group | Rated HP | Stroke | Serial or Application Condition | OEM Reference |
|---|---|---|---|---|---|
| Mercury / Mariner | 50, 55, 60 | 50–60 | 2-Stroke | Application group; verify the specific model and serial number | 47-19453T / 47-19453 |
| Mercury / Mariner | 40 Carb, 3-cylinder | 40 | 4-Stroke | Company-listed application | 47-19453T / 47-19453 |
| Mercury / Mariner | 40, 4-cylinder | 40 | 4-Stroke | Company-listed application | 47-19453T / 47-19453 |
| Mercury / Mariner | 40 EFI, 4-cylinder | 40 | 4-Stroke | Company-listed application | 47-19453T / 47-19453 |
| Mercury / Mariner | 50 EFI, 4-cylinder | 50 | 4-Stroke | Company-listed application | 47-19453T / 47-19453 |
| Mercury / Mariner | 50, 4-cylinder | 50 | 4-Stroke | Company-listed application | 47-19453T / 47-19453 |
| Mercury / Mariner | 60, 4-cylinder | 60 | 4-Stroke | Company-listed application | 47-19453T / 47-19453 |
| Mercury / Mariner | 60 EFI, 4-cylinder | 60 | 4-Stroke | Company-listed application | 47-19453T / 47-19453 |
Technical Specs
- Product Type
- Water pump impeller
- Manufacturer Reference
- Sierra 18-8900
- OEM References
- Mercury Marine 47-19453T and 47-19453
- Application
- Selected Mercury and Mariner 2-stroke 50–60 HP and 4-stroke 40–60 HP outboards
- Outside Diameter
- 3.125 inches (approximately 79.4 mm)
- Inside Diameter
- 0.75 inches (approximately 19.1 mm)
- Vane Style
- High-volume, long-vane design
- Material
- Not specified in the available company product data
What’s in the Box
- 1 × water pump impeller
This listing is for the impeller only. A separate key, gasket, water-pump service kit, or other hardware is not included unless specifically stated in the order details.
Installation Notes
- Confirm the engine model, stroke type, serial number, and existing OEM reference before beginning work.
- Disconnect the battery and follow the manufacturer's service procedure for removing the lower unit.
- Remove the water-pump housing cover and note the orientation of the old impeller vanes.
- Remove the old impeller and clean debris from the pump housing, plate, and surrounding passages.
- Inspect the pump housing, wear plate, drive key, and shaft for damage or abnormal wear. Replace damaged components as required.
- Install the replacement impeller in the correct orientation. Use the service manual's specified lubricant or installation method; do not force the impeller over the shaft.
- Reassemble the water-pump housing and reinstall the lower unit, ensuring the driveshaft, shift linkage, and water tube are correctly aligned.
- Run the engine only with an appropriate water supply and confirm a normal cooling-water telltale stream before returning the boat to service.
Troubleshooting & FAQ
How do I know if this impeller is the right one for my motor?
Match the old impeller or service-manual reference to Mercury 47-19453T, Mercury 47-19453, or the listed replacement references, then verify the engine's exact model, stroke type, and serial-number range. A 40–60 HP rating by itself is not enough to confirm fitment.
What are common signs that an impeller needs replacement?
Possible signs include engine overheating, a weak or missing telltale stream, reduced cooling-water flow, or cracked, brittle, distorted, or missing impeller vanes. Always investigate the complete cooling system if overheating occurs.
How often should I replace the water-pump impeller?
Replacement intervals vary with operating hours, water conditions, storage, and the engine manufacturer's maintenance schedule. Inspect the impeller during scheduled service and replace it whenever the vanes show deterioration or the service manual calls for replacement.
Is a key included?
No key is specified as included with this listing. Confirm the condition and size of the existing drive key and obtain the correct replacement separately if it is worn, damaged, or missing.
Is this an OEM Mercury part?
No. This is an aftermarket Sierra replacement impeller. Mercury Marine part numbers are provided only as OEM references for identification and fitment comparison.
Does this listing include a complete water-pump kit?
No. This listing contains one water pump impeller only. It does not include a housing, wear plate, gasket set, drive key, or complete water-pump repair kit.
What should I do if my engine overheats after installation?
Stop operating the engine and inspect the impeller orientation, drive key, pump housing, water tube, telltale passage, and cooling-water supply. Refer to the engine service manual or have a qualified marine technician diagnose the cooling system before further use.
Safety & Important Information
- Verify the engine model, stroke, serial number, OEM part number, and impeller dimensions before ordering.
- Do not rely on horsepower alone because different engine versions can use different water-pump components.
- Use the correct service-manual procedures and follow all safety precautions when removing or reinstalling the lower unit.
- Never run an outboard without an adequate cooling-water supply.
- This is an aftermarket replacement, not an OEM Mercury component.
- Professional installation is recommended when you are unfamiliar with lower-unit or water-pump service.
About Sea Sierra
- Marine Replacement Parts — We supply replacement components for common outboard maintenance and repair applications.
- Application-Focused Listings — Product references and compatibility information are provided to help you compare the part with your engine.
- Clear Package Information — This listing identifies the impeller-only package so you can order the additional service parts required for your repair.
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