Water Pump Repair Kit for Mercury/Mariner 2-Stroke 15–25 HP and 4-Stroke 9.9–15 HP — Replaces 47-85089T7 and 47-85089Q4
Water Pump Repair Kit for Mercury/Mariner 2-Stroke 15–25 HP and 4-Stroke 9.9–15 HP — Replaces 47-85089T7 and 47-85089Q4 is backordered and will ship as soon as it is back in stock.
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Water Pump Repair Kit for Mercury/Mariner 2-Stroke 15–25 HP and 4-S...
Water Pump Repair Kit for Mercury/Mariner 2-Stroke 15–25 HP and 4-Stroke 9.9–15 HP — Replaces 47-85089T7 and 47-85089Q4 is backordered and will ship as soon as it is back in stock.
Product Details
This water pump repair kit is intended to service the cooling system on selected Mercury and Mariner outboard engines. The listed applications include 2-stroke models from 15 HP through 25 HP produced during the applicable model-year and serial-number ranges, together with specific 4-stroke BigFoot models from 9.9 HP through 15 HP.
The kit is listed as a replacement for Mercury references 47-85089T7, 47-85089Q4, and 47-85089T4. Related aftermarket reference numbers include Sierra 18-3215 and GLM 12107. Always compare the original pump components and verify the complete engine model, year, and serial number before ordering.
- Replacement water-pump service kit for selected Mercury and Mariner outboards.
- Impeller made from CR rubber, with stainless-steel pump components as applicable to the kit.
- Includes the listed impeller, washers, gaskets, key, wear plate, and O-ring.
- Suitable for routine cooling-system service in saltwater or freshwater applications when correctly matched to the engine.
Part Number Matrix
Use these manufacturer and aftermarket references as cross-reference information only. Part-number comparison does not replace model and serial-number verification.
| Brand | Part Number |
|---|---|
| Mercury | 47-85089T7 |
| Mercury | 47-85089Q4 |
| Mercury | 47-85089T4 |
| Sierra | 18-3215 |
| GLM | 12107 |
Engine and Model Compatibility
Confirm the engine brand, model, rated horsepower, stroke, model year, and serial-number range before purchase. The following applications are the listed fitment references for this repair kit.
Mercury/Mariner 2-Stroke Engines
| Brand | Model | Rated HP | Stroke | Years | Reference | Serial or Application Notes |
|---|---|---|---|---|---|---|
| Mercury/Mariner | 15 XD | 15 | 2-Stroke | 1997–1998 | 47-85089T7 | BEL serial number 9927000 and up |
| Mercury/Mariner | 18, 18XD | 18 | 2-Stroke | 1980–1985 | 47-85089T7 | USA serial number 5837437 and up |
| Mercury/Mariner | 20, 20XD | 20 | 2-Stroke | 1986–1987 | 47-85089T7 | USA serial numbers 6443973 through 0T800749 |
| Mercury/Mariner | 25, 25XD | 25 | 2-Stroke | 1980–1987 | 47-85089T7 | USA serial number 5705532 and up |
| Mercury/Mariner | 25, 25XD | 25 | 2-Stroke | 1980–1983 | 47-85089T7 | AUS serial number 8073158 and up |
| Mercury/Mariner | 25, 3-cylinder | 25 | 2-Stroke | 1997 and later | 47-85089T7 | USA serial number 0E268781 and up |
| Mercury/Mariner | 25 Sea Pro; Super 15 | 25; 15 | 2-Stroke | 1988–1998 | 47-85089T7 | USA serial number 0B238464 and up |
Mercury/Mariner 4-Stroke Engines
| Brand | Model | Rated HP | Stroke | Years | Reference | Serial or Application Notes |
|---|---|---|---|---|---|---|
| Mercury/Mariner | BigFoot, 323 cc | 15 | 4-Stroke | 1998 | 47-85089T7 | USA serial number 0G590000 and up |
| Mercury/Mariner | BigFoot, 323 cc | 9.9 | 4-Stroke | 1998 and later | 47-85089T7 | USA serial numbers 0G760300 through 0T979999 |
Technical Specifications
- Product Type
- Water pump repair kit
- Installation
- Replacement water-pump service components
- Impeller Material
- CR rubber
- Other Component Material
- Stainless steel, where specified for the included components
- Package Dimensions
- 6.57 × 5.98 × 1.34 inches (167 × 152 × 34 mm)
- Package Weight
- 0.11 kg (0.24 lb)
- Application
- Selected Mercury and Mariner outboards operating in freshwater or saltwater
What's in the Box
- 1 × Impeller; replacement reference 47-85089-10
- 2 × Plastic washers; replacement reference 12-86645-1
- 2 × Gaskets; replacement reference 27-99326
- 1 × Key; replacement reference 28-8M0032838
- 1 × Wear plate; replacement reference 85083
- 1 × O-ring; replacement reference 25-69202
Installation Notes
- Disconnect the battery or follow the engine manufacturer's applicable safety procedure, then remove the lower unit from the outboard.
- Disassemble the water-pump housing carefully and note the order and orientation of the existing components.
- Clean all mating surfaces and inspect the pump housing, wear plate area, and driveshaft for scoring, distortion, corrosion, or debris.
- Install the supplied wear plate, gaskets, washers, O-ring, and key in the correct order for the specific engine.
- Lubricate the impeller and pump housing with a suitable marine lubricant or soapy water before assembly. Do not use a petroleum product that may damage the rubber.
- Install the impeller on the driveshaft, turning the shaft in the manufacturer's specified direction so the vanes enter the housing correctly.
- Reassemble the pump housing, tighten fasteners to the engine manufacturer's specified torque, and reinstall the lower unit.
- After installation, run the engine according to the manufacturer's procedure and confirm a normal cooling-water discharge before returning the boat to service.
Troubleshooting and FAQ
How do I confirm that this kit fits my Mercury or Mariner engine?
Match the engine's brand, model, horsepower, stroke, model year, and serial number with the compatibility tables. Serial-number verification is especially important for transition-year engines. Compare the original impeller, wear plate, key, and gasket arrangement before installation.
What are common signs of a worn water-pump impeller?
Possible symptoms include overheating at idle or low speed, a weak or missing telltale stream, reduced cooling-water flow, and an engine warning or alarm. Stop operating an overheating engine and investigate the cooling system before further use.
How often should the impeller be replaced?
Inspect the impeller during routine maintenance and replace it when the vanes are cracked, permanently set, damaged, or worn. Replacement intervals vary with usage and water conditions; sandy, silty, and saltwater operation can increase wear.
Is this an OEM Mercury part?
No. This listing is for an aftermarket replacement kit intended to correspond to the listed Mercury, Sierra, and GLM reference numbers. Mercury, Mariner, Sierra, and GLM are trademarks of their respective owners.
Does the kit include all components shown in the package list?
The listed package contains one impeller, two plastic washers, two gaskets, one key, one wear plate, and one O-ring. Confirm the contents against the package and compare them with the original pump assembly before beginning installation.
Safety and Important Information
- Verify the complete engine model and serial number before ordering; horsepower alone is not sufficient to confirm fitment.
- Compare the original part and pump assembly with the listed references and package contents before installation.
- This is an aftermarket replacement product, not an original equipment manufacturer component.
- Follow the engine manufacturer's service instructions, torque specifications, and safety procedures.
- Professional installation is recommended if you are not experienced with outboard lower-unit or water-pump service.
About Sea Sierra
- Marine Replacement Parts — We provide replacement components for common marine maintenance and repair applications.
- Fitment-Focused Listings — Product references and application details are provided to help customers compare parts before ordering.
- Service-Ready Components — Replacement parts are selected for practical maintenance and repair use in marine environments.
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