Aftermarket Water Pump Impeller for Yamaha 20C/25D/28A/30A and Mercury Mariner 20C/25C/28/30/30A

Product Details

This aftermarket water pump impeller is designed for selected Yamaha Outboard and Mercury/Mariner 2-stroke applications. The impeller helps maintain water circulation through the outboard cooling system and is supplied as a single replacement impeller.

Company-listed fitment includes Yamaha 20C, 25D, 28A and 30A models, together with selected Mercury/Mariner 2-stroke 20C, 25C, 28/30 and 30A models. Always compare the engine model code and the original impeller dimensions before ordering.

• Aftermarket replacement water pump impeller for selected 2-stroke outboards.
• Six-blade design with a keyed bore.
• Supplied as one impeller; water pump housing, gaskets, wear plate and other service parts are not included.

Part Number References

The following OEM and aftermarket numbers are listed as reference numbers for this impeller. Confirm the number and dimensions against your original part before installation.

Engine & Model Compatibility

Fitment is limited to the model families listed below. Model codes, production details and lower-unit configurations can vary, so verify your complete model designation and original impeller before purchase.

Technical Specifications

Product Type

Water pump impeller

Application

Selected Yamaha, Mercury and Mariner 2-stroke outboards

Outside Diameter

2.735 in

Bore Diameter

0.653 in

Thickness

0.515 in

Keyway Dimension

0.105 in

Blade Count

6

Installation

Replacement impeller for the water pump assembly

What’s in the Box

• 1 × Water pump impeller

Not included: impeller key, water pump housing, gaskets, wear plate, cup, bolts or other water pump service components.

Installation Notes

1. Switch off the engine, disconnect the battery where applicable and follow the safety instructions in the engine service manual.
2. Place the outboard securely in a vertical position and remove the lower unit according to the manufacturer’s procedure.
3. Remove the water pump cover and take out the old impeller, noting the position of the key and the original blade orientation.
4. Inspect the pump housing, wear plate, key and gaskets for wear or damage. Replace damaged service parts before reassembly.
5. Clean the mating surfaces and confirm that the replacement impeller’s outside diameter, bore, thickness and keyway match the original part.
6. Install the impeller and key correctly in the water pump assembly, following the engine manufacturer’s specified shaft-rotation procedure.
7. Reinstall the pump cover and all fasteners, ensuring the seals and gaskets are correctly seated.
8. Reinstall the lower unit, reconnect any removed components and test the cooling-water flow before operating the engine normally.

Troubleshooting & FAQ

Safety & Important Information

• Verify the complete engine model, stroke type, reference number and dimensions before ordering.
• Do not run the outboard if cooling-water flow is weak or absent.
• Replace damaged keys, gaskets, wear plates or pump housing components as required.
• Professional installation is recommended if you are not familiar with lower-unit or water-pump service.
• This is an aftermarket replacement, not an OEM component.

About Sea Sierra

• Marine Replacement Parts — Practical replacement components for routine outboard maintenance and repair.
• Application-Focused Listings — Product references and listed model information help you compare the part before ordering.
• Fitment Verification — Always match the complete engine model and original component specifications for the best result.