Water Pump Repair Kit – Fits Mercury/Mariner 2-Stroke 15-25 HP & 4-Stroke 9.9-15 HP (Replaces 47-85089T7, 47-85089Q4)
Water Pump Repair Kit – Fits Mercury/Mariner 2-Stroke 15-25 HP & 4-Stroke 9.9-15 HP (Replaces 47-85089T7, 47-85089Q4) 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 Repair Kit – Fits Mercury/Mariner 2-Stroke 15-25 HP &...
Water Pump Repair Kit – Fits Mercury/Mariner 2-Stroke 15-25 HP & 4-Stroke 9.9-15 HP (Replaces 47-85089T7, 47-85089Q4) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Repair Kit – Fits Mercury/Mariner 2-Stroke 15-25 HP & 4-Stroke 9.9-15 HP is designed to restore the cooling system on a range of Mercury and Mariner outboards. It is compatible with 2-Stroke models from 15 HP to 25 HP (1980–1998), including Sea Pro and XD variants, and specific 4-Stroke BigFoot models from 9.9 HP to 15 HP (1998 and newer).
This kit serves as a direct interchange for Mercury part numbers 47-85089T7, 47-85089Q4, 47-85089T4, as well as aftermarket equivalents like Sierra 18-3215 and GLM 12107.
- Engineered for a direct OEM-replacement fit and simple installation.
- Built with durable CR rubber and stainless steel components for reliable use in both salt and freshwater.
- Includes a new impeller, wear plate, gaskets, and all necessary seals for a complete water pump service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.
| Brand | Part Number |
|---|---|
| Mercury | 47-85089T7 |
| Mercury | 47-85089Q4 |
| Mercury | 47-85089T4 |
| Sierra | 18-3215 |
| GLM | 12107 |
Engine & Model Compatibility
Confirm your engine model and year in the tables below. Verifying serial numbers is crucial for ensuring proper fitment.
Mercury/Mariner 2-Stroke Engines: This kit is designed for various 15 HP to 25 HP models produced between 1980 and 1998. Please check your engine's serial number against the ranges listed below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury/Mariner | 15 XD | 15 | 2-Stroke | 1997–1998 | 47-85089T7 | BEL ser# 9927000 & Up |
| Mercury/Mariner | 18, 18XD | 18 | 2-Stroke | 1980–1985 | 47-85089T7 | USA ser# 5837437 & Up |
| Mercury/Mariner | 20, 20XD | 20 | 2-Stroke | 1986–1987 | 47-85089T7 | USA ser# 6443973-0T800749 |
| Mercury/Mariner | 25, 25XD | 25 | 2-Stroke | 1980–1987 | 47-85089T7 | USA ser# 5705532 & Up |
| Mercury/Mariner | 25, 25XD | 25 | 2-Stroke | 1980–1983 | 47-85089T7 | AUS ser# 8073158 & Up |
| Mercury/Mariner | 25 (3-Cyl.) | 25 | 2-Stroke | 1997 & Up | 47-85089T7 | USA ser# 0E268781 & Up |
| Mercury/Mariner | 25 Sea Pro, Super 15 | 25, 15 | 2-Stroke | 1988–1998 | 47-85089T7 | USA ser# 0B238464 & Up |
Mercury/Mariner 4-Stroke Engines: This kit fits specific 9.9 HP and 15 HP BigFoot models from 1998 onward. Check your serial number to ensure a correct match.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury/Mariner | BigFoot (323cc) | 15 | 4-Stroke | 1998 | 47-85089T7 | USA ser# 0G590000 & Up |
| Mercury/Mariner | BigFoot (323cc) | 9.9 | 4-Stroke | 1998+ | 47-85089T7 | USA ser# 0G760300-0T979999 |
Technical Specs
- Product Type
- Water Pump Impeller Repair Kit
- Installation
- Direct OEM Replacement
- Materials
- CR Rubber (impeller), Stainless Steel (components)
- Package Dimensions
- 6.57 × 5.98 × 1.34 inches (167 × 152 × 34 mm)
- Package Weight
- 0.11 kg (0.24 lbs)
- Application
- Designed for salt and freshwater environments
- Warranty
- Limited Lifetime (for Sierra branded version)
What’s in the Box
- 1 x Impeller (Replaces 47-85089-10)
- 2 x Plastic Washer (Replaces 12-86645-1)
- 2 x Gasket (Replaces 27-99326)
- 1 x Key (Replaces 28-8M0032838)
- 1 x Wear Plate (Replaces 85083)
- 1 x O-Ring (Replaces 25-69202)
Installation Notes
- Disconnect the negative battery cable. Remove the lower unit (gearcase) from the outboard motor.
- Carefully disassemble the water pump housing, noting the order and orientation of all components.
- Thoroughly clean all mating surfaces and inspect the inside of the housing for scoring, warping, or corrosion.
- Install the new wear plate, gaskets, and seals provided in the kit.
- Liberally lubricate the new impeller and the inside of the pump housing with silicone grease, marine-grade lubricant, or dish soap to prevent damage during initial startup.
- Slide the new impeller onto the driveshaft, turning the shaft clockwise to help flex the vanes into the housing correctly.
- Reassemble the pump housing, tighten bolts to the manufacturer's specified torque, and reinstall the lower unit.
Troubleshooting & FAQ
How do I confirm this kit fits my specific Mercury/Mariner engine?
The most reliable way is to match your engine's model, year, and serial number to the ranges listed in the compatibility tables. Serial numbers are critical for ensuring an exact match, especially for engines made around transition years.
What are the signs of a failing water pump impeller?
Common signs include the engine overheating at idle or low speeds, a weak or non-existent stream of water from the "telltale" outlet, and in some cases, an engine alarm.
How often should the water pump impeller be replaced?
As a general maintenance guideline, inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of use. Replacement frequency should be increased if operating in sandy, silty, or saltwater conditions.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. The component is manufactured in an ISO 9002 facility and is batch-inspected for quality and consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free, and expedited options will appear at checkout where available for your location.
Warranty & returns?
This product is covered by a 1-year warranty against manufacturing defects under normal use conditions. 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 and specifications against your original part before purchase. If anything differs—even if your model appears on the compatibility list—do not purchase.
- This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
- Professional installation is recommended for safety and to ensure optimal performance.
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 — We offer free standard delivery to most regions, with typical transit times of 5–15 days.
- Manufacturer-Direct Value — Our model provides fair pricing without compromising on materials or quality control.
Payment & Security
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