Water Pump Impeller – Fits Mercury/Mariner/MerCruiser 30-300 HP (Replaces 47-89984T4)

Product Details

This Water Pump Impeller – Fits Mercury/Mariner/MerCruiser 30-300 HP (Replaces 47-89984T4) is a crucial component for maintaining your engine's cooling system. It is designed for a broad range of 2-Stroke outboards from Mercury/Mariner (30-300 HP, 1961–2006) and Force (75-150 HP), as well as MerCruiser MC-I and Alpha One sterndrive engines (1983-1990).

Engineered as a direct interchange for OEM and aftermarket part numbers, this impeller replaces Mercury 47-89984T4, Sierra 18-3017, GLM 89840, and others, ensuring a precise fit and reliable operation.

• Ensures reliable cooling performance as a direct replacement part.
• Constructed from high-strength neoprene rubber with a durable metal alloy insert.
• Features a keyed hub for secure, shaft-driven operation.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Mercury / Mariner: Covers a wide range of 2-stroke outboards from 1961 to 2006, including various 4-cylinder, 6-cylinder, and V-engine configurations.

MerCruiser: Compatible with MC-I and R/MR/Alpha One sterndrive gear housings from 1983 to 1990.

OMC / Johnson / Evinrude: Fits select 2-stroke outboards from 75 HP to 150 HP.

Force: Designed for various 2-stroke outboards from 75 HP to 150 HP.

Technical Specs

Product Type

Water Pump Impeller

Installation

Direct replacement

Dimensions

Hub: 22.2 mm (0.87 in), Diameter: 60.0 mm (2.36 in), Height: 33.8 mm (1.33 in)

Material

Neoprene rubber with metal alloy insert

Number of Blades

6

Keyway

Yes

Housing Compatibility

Standard, Alpha One, MC-I, MR

Weight

99 g (3.5 oz)

Other Attributes

Shaft-driven impeller with metal hub and flexible neoprene blades

What’s in the Box

• 1 x Water Pump Impeller (47-89984T4)

Installation Notes

1. Disconnect the battery to prevent accidental starting.
2. Place a drain pan under the lower unit and remove the gearcase oil drain/fill screws to drain the lubricant.
3. Remove the bolts securing the lower unit (gearcase) to the engine. Carefully separate the unit.
4. Unbolt and remove the water pump housing cover to expose the old impeller.
5. Note the rotational direction of the old impeller blades before removing it. Pull the old impeller off the driveshaft, removing the key if present.
6. Clean and inspect the water pump housing and wear plate for scoring, warping, or damage. Replace if necessary.
7. Lightly lubricate the new impeller and insert the key into the driveshaft. Slide the new impeller onto the shaft.
8. Install the water pump housing, rotating the driveshaft in its normal direction of operation to bend the blades correctly.
9. Reassemble the pump housing, ensuring all seals and gaskets are correctly seated. Torque bolts to manufacturer specifications.
10. Reinstall the lower unit, ensuring the driveshaft, shift shaft, and water tube are properly aligned.
11. Refill the lower unit with fresh gear oil.
12. Once fully assembled, test the engine in a suitable water source to confirm proper cooling system operation.

Troubleshooting & FAQ

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.