8M0251131 Water Pump Impeller Kit for Mercury OptiMax DFI EFI V135 V140 V150 V175 V200 | JLM Marine

Water Pump Impeller Kit – Fits Mercury OptiMax DFI EFI V135 V140 V150 V175 V200

This comprehensive water pump impeller kit is designed for Mercury OptiMax 135-175HP DFI 2.5L models (1999-2018), 150-200HP EFI models (1998-2015, serial #0G960500 to 1B227000 and up), and V135, V140, V150, V175, V200 6-cylinder engines. It provides a complete rebuild solution for your marine water pump system, ensuring reliable cooling performance and engine protection.

This kit directly replaces OEM part number 8M0251131 and includes all essential components—impeller, gaskets, seals, o-rings, housing, thermostat, fuel filter, and gear oil pump—for a thorough, professional-grade service.

• Complete 31-piece kit with impeller, gaskets, seals, housing, thermostats, and more
• Fits OptiMax DFI and EFI V6 engines from 135HP to 200HP
• Includes fuel filter and gear oil pump for comprehensive maintenance

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here's a guide to help you identify your engine's serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

This comprehensive kit includes 31 components for a complete water pump rebuild:

• 47-89984T4 Water Pump Impeller × 1
• 56654 Impeller Key × 1
• 32435 1 Wear Plate × 1
• 27-32438 Gasket × 1
• 27-426311 Gasket × 1
• 27-856081 Gasket × 1
• 27-856091 Gasket × 1
• 27-856704 Gasket × 1
• 25-30271 Seal × 1
• 32-29804T Water Tube Guide × 1
• 26-455771 Seal × 1
• 12-191832 Drain Gasket × 2
• 2107 Seal × 1
• 2108 Seal × 1
• 12-31266 Gasket × 1
• 12-49221-1 Gasket × 1
• 25-30613 O-Ring × 1
• 25-33145 O-Ring × 1
• 25-90011 O-Ring × 1
• 25-38099 O-Ring × 1
• 25-30224 O-Ring × 1
• 29967 Pin × 1
• 10-96411 Screw × 1
• 48752T Insert Cup × 1
• 26-38970 Seal × 1
• 46-96148T1 Water Pump Housing × 1
• 833072003 Thermostat × 2
• 816296Q03 Fuel Filter × 1
• 8M007119 Drain Gasket × 1
• 830749 Drain Gasket × 3
• 24OP149 Gear Oil Pump × 1

Installation Guide

1. Disconnect the battery and remove the lower unit from the outboard motor following your service manual procedures.
2. Remove the old water pump housing and carefully extract the worn impeller using needle-nose pliers; inspect the driveshaft for damage or wear.
3. Clean all mating surfaces thoroughly, removing old gasket material and debris with a gasket scraper and solvent.
4. Install the new wear plate onto the pump housing base, ensuring proper alignment with dowel pins.
5. Lubricate the new impeller with glycerin or soapy water (never petroleum-based products), then slide it onto the driveshaft with vanes oriented in the correct rotation direction.
6. Insert the impeller key into the driveshaft slot to lock the impeller in position.
7. Apply a thin layer of marine grease to new gaskets and position them on the housing, replacing all seals and o-rings as indicated in the kit.
8. Install the water tube guide and ensure the water tube inserts properly into the pump housing without kinking.
9. Carefully position the new water pump housing over the impeller, gently rotating the driveshaft to help seat the impeller vanes.
10. Install the insert cup, seals, and drain gaskets according to your engine's exploded diagram; torque all fasteners to manufacturer specifications.
11. Replace the fuel filter and install the thermostats into their housings with new gaskets, ensuring correct orientation (spring side down).
12. Reinstall the lower unit, refill the gear oil using the included gear oil pump, reconnect the battery, and perform a water flow test before launching.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my Mercury engine?
A: Cross-reference your engine model, horsepower, year, and serial number with the compatibility table above. OptiMax DFI models from 1999-2018 (135-175HP, excluding Pro XS) and EFI models from 1998-2015 (150-200HP, serial #0G960500 to 1B227000 and up) are compatible. Check your lower unit's current parts or consult Mercury's parts diagrams to verify.

Q: How often should I replace my water pump impeller?
A: Mercury recommends replacing the impeller every 2-3 years or 200-300 hours of operation, whichever comes first. If you notice overheating, reduced water flow from the tell-tale, or the engine has been run dry, replace the impeller immediately.

Q: What are the signs that my water pump is failing?
A: Common symptoms include weak or no water stream from the tell-tale indicator, engine overheating, steam from the powerhead, reduced performance, or an audible high-temperature alarm. Inspect the impeller if any of these occur.

Q: Why does this kit include a fuel filter and gear oil pump?
A: This is a comprehensive service kit designed for complete lower unit maintenance during water pump replacement. The fuel filter ensures clean fuel delivery to your EFI or DFI system, and the gear oil pump allows proper refilling of the lower unit after service.

Q: Can I use this kit on Mercury Pro XS models?
A: No, this kit explicitly does not fit Pro XS models. It is designed for standard OptiMax DFI and EFI engines only; Pro XS engines require different components.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. Returns are accepted within our standard return window (unused & in original condition); please contact us for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.