Water Pump Impeller Kit – Fits Mercury Marine 2-Cycle Outboards 30-70 HP (Replaces Mercury 46-77177A3, Sierra 18-3324)
Water Pump Impeller Kit – Fits Mercury Marine 2-Cycle Outboards 30-70 HP (Replaces Mercury 46-77177A3, Sierra 18-3324) 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 Marine 2-Cycle Outboards 30-...
Water Pump Impeller Kit – Fits Mercury Marine 2-Cycle Outboards 30-70 HP (Replaces Mercury 46-77177A3, Sierra 18-3324) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit is a complete assembly designed to restore the cooling system on Mercury and Mariner 2-cycle outboards from 30 to 70 HP (1977–1997). The kit includes the impeller, housing, gaskets, and all necessary hardware for a full replacement, ensuring your engine maintains proper operating temperature.
It serves as a direct replacement for Mercury parts 46-77177A3/77177A3 and interchanges with Sierra 18-3324, GLM 12100, and Mallory 9-48312, among others.
- Installs as a direct replacement for original OEM components.
- Engineered with a durable neoprene rubber impeller and a robust PA66 nylon housing.
- Includes all essential gaskets, o-rings, and seals for a complete rebuild.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 46-77177A3 |
| Mercury | 77177A3 |
| Sierra | 18-3324 |
| GLM | 12100 |
| Mallory | 9-48312 |
| UanofCn | 18-3324 |
| NorthBoat | 77177A3 |
| Tutor Auto | 77177A3 |
| SeaSierra | 77177A3 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury/Mariner models, verify your engine's serial number falls within the specified range for a guaranteed fit.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | Jet | 30 | 2-Stroke | 1989–1997 | 46-77177A3 | 4 cylinders, 0C159200 through 0G589999 |
| Mercury/Mariner | [Multiple] | 35 | 2-Stroke | 1984–1989 | 46-77177A3 | 2 cylinders, 6445653 through 0B110788 |
| Mercury/Mariner | 402 | 40 | 2-Stroke | 1978–1979 | 46-77177A3 | 2 cylinders |
| Mercury/Mariner | [Multiple] | 40 | 2-Stroke | 1980–1983 | 46-77177A3 | 2 cylinders |
| Mercury/Mariner | [Multiple] | 40 | 2-Stroke | 1989 & Up | 46-77177A3 | 4 cylinders |
| Mercury/Mariner | [Multiple] | 45 | 2-Stroke | 1986 & Up | 46-77177A3 | 4 cylinders |
| Mercury/Mariner | [Multiple] | 50 | 2-Stroke | 1978–1985 | 46-77177A3 | 4 cylinders |
| Mercury/Mariner | [Multiple] | 50 | 2-Stroke | 1984–1990 | 46-77177A3 | 3 cylinders |
| Mercury/Mariner | [Multiple] | 60 | 2-Stroke | 1984–1990 | 46-77177A3 | 3 cylinders |
| Mercury/Mariner | [Multiple] | 65 | 2-Stroke | 1976 | 46-77177A3 | 3 cylinders |
| Mercury/Mariner | [Multiple] | 70 | 2-Stroke | 1977–1983 | 46-77177A3 | 3 cylinders |
Technical Specs
- Product Type
- Water Pump Impeller Repair Kit with Housing
- Installation
- Direct replacement for OEM components
- Material
- Neoprene marine rubber impeller and O-rings, nylon PA66 plastic water pump housing, stainless steel components
- Housing Material
- Nylon PA66 plastic
- Housing Color
- Black
- Weight
- 0.31 kg (10.8 oz)
- Recommended Service Interval
- Once per year or every 100 hours of operation
- Warranty
- Varies by manufacturer (Tutor Auto offers lifetime warranty)
- Other Technical Attributes
- Pre-assembled water pump kit contains all necessary components for complete rebuild
What’s in the Box
- 1 x Impeller (89983T)
- 1 x Upper Pump Housing (77822A1)
- 1 x Water Pump Base/Lower Housing
- 1 x Face Plate (32768)
- 1 x Upper Water Pump Gasket (19551)
- 1 x Lower Water Pump Gasket (19553)
- 2 x Gasket (19552)
- 1 x Drain Gasket
- 1 x Lower Water Pump Base to Face Plate Gasket
- 1 x Upper Face Plate to Body Gasket
- 1 x Water Pump Base Gasket
- 1 x Drain Plug Gasket
- 1 x O-Ring (25-26722)
- 2 x Drain Plug Seal (26-830749)
- 2 x O-Ring (805726)
- 1 x Key/Drive Key (8M0032837)
- 1 x Rubber (25-20273)
- 1 x Shift Bracket Seal (37721001)
Installation Notes
- Disconnect the negative battery terminal.
- Place a drain pan under the lower unit and remove the gear lube drain/fill screws to drain the oil.
- Remove the bolts securing the lower unit (gearcase) to the upper leg.
- Carefully separate the lower unit from the driveshaft housing. Note the position of the shift shaft.
- Unbolt and remove the old water pump housing.
- Slide the old impeller, key, wear plate, and gaskets off the driveshaft.
- Thoroughly clean all mating surfaces, removing any old gasket material or sealant.
- Install the new lower gasket, wear plate, and drive key. Slide the new impeller onto the driveshaft, turning it clockwise to seat the vanes correctly.
- Install the upper gasket and new housing, securing it with the original bolts torqued to manufacturer specs.
- Re-install the lower unit, ensuring the driveshaft, water tube, and shift shaft align properly.
- Refill the lower unit with fresh gear lube from the bottom hole until it flows from the top hole, then replace both screw seals and screws.
- Reconnect the battery and test the engine using a water supply (flushing muffs) to confirm cooling system function.
Troubleshooting & FAQ
How do I know if this kit fits my engine?
The best way to confirm fitment is to check your engine's model, horsepower, and year against the compatibility table. For Mercury/Mariner engines, also verify your serial number is within the range listed in the notes column.
What are common signs of a failing water pump impeller?
Symptoms include the engine running hotter than normal (overheating), a weak or non-existent water stream from the "telltale" outlet, and visible cracks, stiffness, or damage to the old impeller vanes during inspection.
How often should I replace the water pump impeller kit?
For preventative maintenance, we recommend replacing the entire water pump kit, including the housing, once per year or every 100 hours of operation, whichever comes first. This is especially important if you operate in saltwater or debris-heavy water.
Why is my engine overheating after installing the new kit?
Common causes include: incorrect impeller installation (vanes folded the wrong way), a blocked water intake or outlet tube, air leaks from improperly seated gaskets, or a thermostat that is stuck closed. Double-check that all components were installed correctly and that there are no blockages in the cooling system.
Does this kit include the upper and lower housing?
Yes, this is a complete kit that includes the upper pump housing, water pump base (lower housing), face plate, impeller, and all required gaskets and seals for a full rebuild.
What is the difference between an OEM and an aftermarket part?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials, often offering better value. Our parts are manufactured in an ISO 9001 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 product is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter any issues, please contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. See our policy page or reach out for instructions.
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.
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