Water Pump Impeller Kit – Fits Mercury/Mariner 30-70 HP 2-Stroke Outboards (Replaces 77177A3, 46-77177A3)
Water Pump Impeller Kit – Fits Mercury/Mariner 30-70 HP 2-Stroke Outboards (Replaces 77177A3, 46-77177A3) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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Water Pump Impeller Kit – Fits Mercury/Mariner 30-70 HP 2-Stroke Ou...
Water Pump Impeller Kit – Fits Mercury/Mariner 30-70 HP 2-Stroke Outboards (Replaces 77177A3, 46-77177A3) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit provides a complete solution for servicing the lower unit of Mercury/Mariner 2-stroke outboard motors from 30–70 HP (1977–1997). It is designed to restore cooling system performance and prevent engine overheating on models including 30 JET, 35 HP, 40 HP, 45 HP, 50 HP, 60 HP, 65 HP, and 70 HP.
It serves as a direct interchange for several part numbers, including Mercury 46-77177A3/77177A3, Sierra 18-3324, Mallory 9-48312, and GLM 12100, ensuring broad compatibility for repairs and maintenance.
- Installation Location: Mounts in the lower unit/gearcase as a direct-fit replacement.
- Housing Material: Constructed from durable Nylon PA66 plastic for longevity.
- Complete Kit: Includes the impeller, upper housing, base, face plate, and all required gaskets and seals for a comprehensive overhaul.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket providers.
| Brand | Part Number |
|---|---|
| Mercury | 46-77177A3 |
| Mercury | 77177A3 |
| Sierra | 18-3324 |
| Mallory | 9-48312 |
| GLM | 12100 |
Engine & Model Compatibility
Confirm your engine model/year in the table below. Serial numbers are critical for ensuring correct fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 30 JET | 30 | 2-Stroke | 1989–1997 | 46-77177A3 | Serial # 0C159200-0G589999 |
| Mercury | 35 | 35 | 2-Stroke | 1984–1989 | 46-77177A3 | Serial # 6445653 & Up |
| Mercury | 402 | 40 | 2-Stroke | 1978–1979 | 46-77177A3 | Serial # 4860103-5556229 |
| Mercury | 40 (2 CYL) | 40 | 2-Stroke | 1980–1983 | 46-77177A3 | Serial # 5556230-6445653 |
| Mercury | 40 (4 CYL) | 40 | 2-Stroke | 1989–1997 | 46-77177A3 | Serial # 0C159200 & Up |
| Mercury | 45 (4 CYL) | 45 | 2-Stroke | 1986–1997 | 46-77177A3 | Serial # 5531630 & Up |
| Mercury | 50 (4 CYL) | 50 | 2-Stroke | 1978–1985 | 46-77177A3 | Serial # 496205-6 & Up |
| Mercury | 50 (3 CYL) | 50 | 2-Stroke | 1984–1990 | 46-77177A3 | Serial # 6428681-0D000749 |
| Mercury | 60 (3 CYL) | 60 | 2-Stroke | 1984–1990 | 46-77177A3 | Serial # 6428681-0D000749 |
| Mercury | 65 (650) (3 CYL) | 65 | 2-Stroke | 1976 | 46-77177A3 | Serial # 4382057-4571651 |
| Mercury | 70 (3 CYL) | 70 | 2-Stroke | 1979–1983 | 46-77177A3 | Serial # 4977157-6428680 |
Technical Specs
- Product Type
- Water Pump Impeller Kit with Housing
- Installation
- Lower unit/gearcase replacement
- Housing Material
- Nylon PA66 Plastic
- Housing Color
- Black
- Dimensions
- 152.4 mm × 102.9 mm × 52.1 mm (6" × 4.06" × 2.05")
- Weight
- 0.22 kg (0.5 lb)
- Warranty
- 30-day return/replacement (Amazon standard)
- Other Technical Attributes
- Complete kit including impeller, housing, and all required gaskets
What’s in the Box
- 1 x Water Pump Impeller (47-89983T)
- 1 x Upper Pump Housing (77822A1)
- 1 x Water Pump Base (46-77177A1)
- 1 x Face Plate (32768/54705)
- 1 x Impeller Key (8M0032837)
- 1 x Drain Gasket (12-20260)
- 1 x Lower Water Pump Base to Face Plate Gasket (27-19553)
- 1 x Upper Face Plate to Body Gasket (27-32770/27-19551)
- 1 x Water Pump Base Gasket (27-32771)
- 1 x Water Pump Base Gasket (27-77417/27-19552)
- 1 x Drain Plug (12-49221-1)
- 1 x O-Ring (25-26722)
- 1 x Rubber Washer (25-20273)
- Various seals and additional O-rings
Installation Notes
- Disconnect the engine's battery and shift the outboard into the neutral position.
- Locate and remove the lower unit (gearcase) mounting bolts, allowing the unit to drop down.
- Carefully unbolt and detach the old water pump housing assembly from the lower unit.
- Remove the old impeller, face plate, gaskets, and impeller key from the driveshaft.
- Thoroughly clean all mating surfaces, removing any old gasket material or corrosion.
- Install the new lower gasket, face plate, and impeller key onto the driveshaft.
- Slide the new impeller onto the driveshaft, turning the shaft clockwise to bed the vanes correctly.
- Apply a thin layer of marine grease to the inside of the new housing and install it with new gaskets.
- Securely tighten the housing bolts to the manufacturer's recommended torque.
- Re-install the lower unit, ensuring the driveshaft, shift shaft, and water tube are properly aligned.
- Tighten the lower unit bolts, reconnect the battery, and test the engine in water to verify a strong telltale stream.
Troubleshooting & FAQ
How do I know if this kit fits my motor?
Check your motor's model, HP, and serial number against the "Engine & Model Compatibility" table. This kit fits specific Mercury and Mariner 30-70 HP 2-stroke outboards from 1977–1997. The serial number is critical for an exact match.
What are the signs of a failing water pump impeller?
Common signs include a weak or non-existent water stream from the "telltale" outlet, engine overheating alarms, steam from the exhaust, and reduced engine performance, especially at low speeds.
How often should the water pump impeller be replaced?
For preventative maintenance, it is recommended to inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of operation. Replacement frequency should be increased in saltwater or high-sediment environments.
Is the housing included in this kit?
Yes, this is a complete kit that includes the upper pump housing, water pump base, impeller, face plate, gaskets, and all necessary seals and O-rings for a full replacement.
My serial number isn't listed but the model and year match. Will it fit?
We strongly advise against purchasing if your serial number does not fall within the specified ranges. Manufacturers often make mid-year design changes, and the serial number is the only way to guarantee correct fitment.
What is the difference between an OEM part and this aftermarket kit?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. All our parts are manufactured in an ISO 9002 certified facility and are batch-inspected for quality and consistency.
How fast is shipping and what does it cost?
We ship worldwide quickly—typical transit time is 5–15 days. Standard shipping is free to most regions, with expedited options available at checkout where applicable.
What is the warranty and return policy?
This kit is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter any issues, contact our support team with your order details. Returns are accepted within our standard window for items that are unused and in their original condition. Please see our policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
- Professional installation is highly recommended for safety, performance, and to prevent damage to your engine.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
- Fast Global Fulfillment — Enjoy free standard delivery to most regions in 5–15 days, with expedited options available.
- Manufacturer-Direct Value — We deliver fair pricing on reliable components by eliminating middlemen, without compromising on materials or quality control.
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