Water Pump Impeller Kit – Fits Mercury Mariner 2-Stroke 3.5–9.8 HP (Replaces 47-89980T1, 47-89980Q1)

Product Details

This water pump impeller kit is designed for selected Mercury and Mariner 2-stroke outboard motors in the 3.5–9.8 HP range, including 3.5 HP, 3.6 HP, 3.9 HP, 4 HP, 4.5 HP, 7.5 HP, and 9.8 HP models manufactured during the listed model years. Please verify the exact model, year, serial number, and impeller dimensions before ordering.

The kit is listed as a replacement for Mercury references including 47-89980T1, 47-89980Q1, 89980, 89980B, and 68988, as well as aftermarket references such as Sierra 18-3054, GLM 12270, and CEF 500314. These references should be used for cross-checking only; always compare the original part and engine serial number.

• Installs in the lower unit water pump to restore cooling-water circulation.
• Includes a neoprene impeller and stainless steel wear plate for dependable service.
• Critical fitment note: This kit uses a 0.438 in (11.1 mm) impeller inside diameter. Measure the existing impeller or driveshaft before purchase.

Part Number Matrix

Use these references to cross-check the replacement part across OEM and aftermarket catalogs.

Engine & Model Compatibility

The following model and year information is provided as a compatibility guide. Confirm the engine model, production origin, serial number, and impeller dimensions before ordering.

Serial Number Compatibility

Technical Specifications

Product Type

Water pump impeller kit

Installation Location

Lower unit and driveshaft water pump

Materials

Neoprene impeller, SS316 wear plate, nylon PA66 tube

Impeller Blades

6

Impeller Height

14.4 mm (0.57 in)

Impeller Inside Diameter

11.1 mm (0.438 in)

Impeller Outside Diameter

31.8 mm (1.250 in)

Fitting Type

Internal shaft mounting

Weight

23 g (0.811 oz)

What's in the Box

• 1 × Impeller, replacement for 47-89980 and 89980B references
• 1 × Wear plate, replacement for 46895 reference
• 1 × Woodruff key
• 1 × Water guide tube sleeve
• 3 × O-rings

Installation Notes

1. Confirm fitment first: Mercury used different driveshaft and impeller dimensions in some horsepower ranges. This kit is for the smaller 0.438 in impeller inside diameter. Do not install it if the original impeller has a larger opening.
2. Disconnect the spark plug leads to prevent accidental starting and place the outboard in neutral.
3. Remove the bolts securing the lower unit to the upper leg. Lower the unit carefully while observing the shift-shaft linkage.
4. Place the lower unit on a stable workbench and remove the water pump housing.
5. Remove the old impeller, wear plate, gaskets, and seals. Note the orientation of each part.
6. Clean the mating surfaces and remove old gasket material, debris, and corrosion.
7. Install the replacement wear plate, gaskets, and O-rings included in the kit.
8. Install the new impeller on the driveshaft with the Woodruff key correctly seated. A small amount of dish soap may be used to lubricate the housing interior.
9. Rotate the driveshaft clockwise while lowering the pump housing over the impeller so the blades set correctly.
10. Secure the housing and tighten its fasteners to the engine manufacturer's recommended torque.
11. Reinstall the lower unit, aligning the water tube, driveshaft splines, and shift shaft.
12. Test the engine with an appropriate water supply, such as flushing muffs or a test tank, and check for a strong tell-tale stream.

Troubleshooting & FAQ

Safety & Important Information

• Verify the model, year, serial number, production origin, part dimensions, and original impeller before purchase. Pay particular attention to the 0.438 in (11.1 mm) impeller inside diameter.
• This is an aftermarket replacement part and is not manufactured by or affiliated with Mercury, Mariner, Sierra, GLM, or CEF.
• Professional installation is recommended when you are not familiar with lower-unit service. Incorrect installation can cause overheating or engine damage.

About Sea Sierra

• Pro-Grade Standards — We supply marine replacement parts designed for demanding saltwater and freshwater operating conditions.
• Fast Global Fulfillment — Standard delivery is available to most regions, with typical transit times of 5–15 days.
• Manufacturer-Direct Value — We work directly with manufacturers to offer competitive pricing while maintaining material and quality-control standards.