Water Pump Impeller Maintenance Kit – Fits Mercury/Mariner/Tohatsu 4–6 HP 4-Stroke (Replaces 8M0120836, 3GR-87500-0)
Water Pump Impeller Maintenance Kit – Fits Mercury/Mariner/Tohatsu 4–6 HP 4-Stroke (Replaces 8M0120836, 3GR-87500-0) is backordered and will ship as soon as it is back in stock.
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Water Pump Impeller Maintenance Kit – Fits Mercury/Mariner/Tohatsu ...
Water Pump Impeller Maintenance Kit – Fits Mercury/Mariner/Tohatsu 4–6 HP 4-Stroke (Replaces 8M0120836, 3GR-87500-0) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Maintenance Kit supplies service components for cooling-system maintenance on selected Mercury and Mariner 4–6 HP 4-Stroke outboard engines and compatible Tohatsu 4–6 HP 4-Stroke models.
The kit is listed as an aftermarket replacement for Mercury reference number 8M0120836 and Tohatsu reference number 3GR-87500-0. Confirm the engine model, serial-number range, and the original component numbers before ordering.
- Designed for replacement of the listed water-pump and related service components.
- Combines impeller, gasket, seal, filter, thermostat, and related maintenance parts in one service kit.
- Supports routine cooling-system service and restoration of proper water-pump operation when installed correctly.
Part Number Matrix
Use these reference numbers when comparing the kit with your existing engine parts and service information.
| Brand | Part Number |
|---|---|
| Mercury | 8M0120836 |
| Tohatsu | 3GR-87500-0 |
Engine & Model Compatibility
Compatibility should be confirmed using the engine model, year, serial number, and service-manual part references together. The listed Mercury and Mariner application is for 4/5/6 HP EFI 4-Stroke outboards from 2015 and newer with serial number 0R411838 and above. The kit is also listed for compatible Tohatsu MFS4, MFS5, and MFS6 4-Stroke models; specific Tohatsu year and serial-number ranges should be verified before purchase.
| Brand | Model | Rated HP | Stroke | Years | Reference Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury / Mariner | 4 HP EFI | 4 | 4-Stroke | 2015 and newer | 8M0120836 | Serial number 0R411838 and above |
| Mercury / Mariner | 5 HP EFI | 5 | 4-Stroke | 2015 and newer | 8M0120836 | Serial number 0R411838 and above |
| Mercury / Mariner | 6 HP EFI | 6 | 4-Stroke | 2015 and newer | 8M0120836 | Serial number 0R411838 and above |
| Tohatsu | MFS4 / MFS5 / MFS6 | 4–6 | 4-Stroke | Verify by model and serial number | 3GR-87500-0 | Confirm application against the service manual |
Technical Specs
- Product Type
- Outboard water-pump and maintenance service kit
- Installation
- Replacement installation; follow the engine service manual
- Fuel Type
- Gasoline
- Weight
- 0.21 kg (0.46 lb)
- Package Dimensions
- Approximately 100 × 92 × 76 mm (3.88 × 3.63 × 3.00 in)
- Purpose
- Cooling-system maintenance and related outboard service
What’s in the Box
- 1 × Water Pump Impeller — 47-16154-3
- 1 × Cotter Pin — 8150264
- 1 × Pin Key — 28-16155
- 1 × Thermostat — 804540
- 1 × Thermostat Gasket — 27-8M0214960
- 1 × O-Ring — 25-16131
- 1 × Oil Seal — 26-16130
- 1 × Fuel Filter — 35-8M0157133
- 1 × Gasket — 8035161
- 2 × Drain Gasket — 27-95220
Installation Notes
- Follow the engine manufacturer’s service procedure and make sure the engine cannot start accidentally before beginning work.
- Disconnect the battery, where fitted, and remove the spark-plug lead as specified by the service manual.
- Access the lower unit by disconnecting the shift linkage, if applicable, and removing the retaining bolts.
- Carefully remove the lower unit from the outboard.
- Open the water-pump housing on top of the gearcase and remove the retaining hardware.
- Remove the old impeller and related service components, noting their orientation and order.
- Clean the pump housing and mating surfaces before installing replacement parts.
- Install the new impeller in the correct rotational orientation and use the new gaskets, seals, and related parts as appropriate for the engine.
- Reassemble the water-pump housing and reinstall the lower unit, aligning the driveshaft, shift linkage, and water tube correctly.
- Run the engine only with an adequate water supply and confirm proper cooling-water flow before returning it to service.
Troubleshooting & FAQ
Which engines does this kit fit?
It is listed for selected Mercury and Mariner 4–6 HP EFI 4-Stroke outboards from 2015 and newer with serial numbers 0R411838 and above. It is also listed for compatible Tohatsu MFS4, MFS5, and MFS6 4-Stroke models. Always verify the complete model and serial-number application before ordering.
How do I confirm this is the right part?
Match the engine brand, model, horsepower, stroke, year, serial number, and the reference numbers shown above. Compare the existing impeller and service components with the listing images and consult the engine service manual if any detail differs.
What are the signs of a worn water-pump impeller?
Possible symptoms include weak or absent water flow from the telltale, overheating warnings, steam from the exhaust, or abnormal engine temperature. Stop operating an overheating engine and investigate the cooling system before further use.
How often should the water pump be serviced?
Replace the impeller and inspect related cooling-system components according to the engine manufacturer’s maintenance schedule. Service may be needed more frequently when operating in saltwater, sandy water, or water containing debris.
Is this an OEM part?
This listing is for an aftermarket replacement maintenance kit, not an original equipment manufacturer kit. The reference numbers are provided for comparison and application checking; they do not change the aftermarket status of the product.
What should I do if the components do not match?
Do not install parts that differ in size, shape, number of blades, gasket arrangement, or fit. Confirm the complete engine model and serial number against the service manual before proceeding.
Safety & Important Info
- Verify the engine model, year, horsepower, stroke, serial-number range, and reference part number before purchase.
- Do not run the outboard without an adequate water supply.
- Allow the engine to cool before servicing the water pump or thermostat.
- This is an aftermarket replacement kit, not an OEM component.
- Professional installation is recommended when the correct service procedure is uncertain.
About Sea Sierra
- Marine Replacement Parts — Service components for routine outboard maintenance and repair.
- Application-Focused Listings — Reference numbers and compatibility information are provided to help identify the correct replacement.
- Customer Support — Contact support with your engine model and serial-number information when application assistance is needed.
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