Water Pump Cartridge Gasket for Yamaha 40HP/50HP 2-Stroke Outboards – Replaces 663-44324-A0

Product Details

This aftermarket water pump cartridge gasket is designed as a replacement sealing component for selected Yamaha 40HP and 50HP 2-stroke outboard water pump assemblies. It installs between the applicable water pump components to help maintain a proper seal and support reliable cooling-system operation.

This listing is for a gasket only. It is not an impeller, water pump repair kit, complete water pump assembly, or gasket-and-impeller kit.

The gasket is identified for replacement of Yamaha OEM part number 663-44324-A0. Always compare the part number, gasket shape, mounting-hole pattern, engine model, year, and serial-number range with your original component and service information before ordering.

• Water pump cartridge gasket replacement
• Helps seal the mating surfaces within the water pump assembly
• Suitable for applicable freshwater and saltwater outboard service environments
• Single replacement gasket; other water pump components are not included

Part Number Matrix

Use the reference below to compare the replacement gasket with the applicable manufacturer part number.

Engine & Model Compatibility

This gasket is listed for selected Yamaha 40HP and 50HP 2-stroke outboards. Exact application can vary by model designation, production year, shaft configuration, and serial-number range, so the general horsepower description alone is not sufficient to confirm fitment.

Technical Specifications

Part Type

Water pump cartridge gasket

Application

Selected Yamaha 2-stroke outboard water pump assemblies

Horsepower Reference

40 HP and 50 HP

Replacement Reference

Yamaha OEM 663-44324-A0

Product Configuration

Single gasket, not a kit

What's in the Box

• 1 × Water pump cartridge gasket

Not included: impeller, impeller key, water pump housing, base gasket, wear plate, fasteners, sealant, or other water pump components.

Installation Notes

1. Disconnect the battery and remove the safety lanyard before beginning service. Follow the engine service manual for all safety procedures.
2. Remove the lower unit according to the manufacturer’s service instructions.
3. Disassemble the water pump only as far as required to access the cartridge gasket.
4. Remove the old gasket and clean all mating surfaces completely. Do not scratch or distort the sealing surfaces.
5. Compare the replacement gasket with the removed gasket and confirm that all openings and mounting holes align.
6. Install the gasket in the correct orientation. Do not reuse a compressed or damaged gasket.
7. Reassemble the water pump components and torque fasteners according to the engine service manual.
8. Reinstall the lower unit and reconnect all removed components.
9. Run the engine using the proper water-supply method and verify telltale flow, cooling performance, and the absence of leaks before normal operation.

Maintenance & Troubleshooting

Replace the gasket whenever the water pump is opened and the existing gasket is removed, or whenever inspection shows compression damage, splitting, distortion, hardening, or leakage. Gasket replacement intervals depend on engine use, storage conditions, water exposure, and the maintenance schedule for the specific outboard.

Is this an impeller?

No. This product is a water pump cartridge gasket only. The impeller and other water pump components must be purchased separately unless specifically stated in another listing.

Does this include an impeller key?

No. The package contains one gasket only. An impeller key, impeller, housing, wear plate, and other components are not included.

Will this fit every Yamaha 40HP or 50HP outboard?

No. Horsepower and stroke type are general application references. Confirm the complete engine model, production year, serial-number range, water pump configuration, and OEM reference number before installation.

Can I reuse the old gasket if it looks intact?

Reuse is not recommended. Once removed, a gasket may no longer seal correctly because it can be compressed, hardened, distorted, or damaged during disassembly. Install a new gasket during water pump service.

Do I need gasket sealant?

Use sealant only when required by the engine manufacturer’s service instructions. Do not apply sealant that could obstruct water passages or alter gasket seating.

What symptoms may indicate a water pump sealing problem?

Possible symptoms include water leakage at the pump, reduced telltale flow, overheating, or visible gasket deterioration. These symptoms can also be caused by a worn impeller, damaged housing, blocked passages, incorrect assembly, or other cooling-system faults.

Is this an OEM part?

No. This is an aftermarket replacement gasket referenced to Yamaha OEM part number 663-44324-A0. Yamaha is a trademark of its respective owner and is used only to identify application and compatibility.

Safety & Important Information

• Verify the OEM reference, gasket profile, engine model, year, and serial-number range before ordering.
• Do not operate an outboard with inadequate cooling-water flow or signs of overheating.
• Use the manufacturer’s service manual for disassembly procedures, torque values, sealant requirements, and testing instructions.
• Professional installation is recommended when lower-unit or water-pump service is outside your experience.
• This is an aftermarket replacement component and is not manufactured by Yamaha.

About Sea Sierra

• We supply replacement marine components for routine maintenance and repair applications.
• Each listing identifies the component type and known manufacturer reference to help with part comparison.
• For the best fitment result, compare the original part and complete engine identification before purchase.