Water Pump Impeller Kit – Fits Mercury/Tohatsu/Nissan 25-30 HP 4-Stroke (Replaces 853792A07)

Water Pump Impeller Kit – Fits Mercury/Tohatsu/Nissan 25-30 HP 4-Stroke

This water pump impeller repair kit is designed for Mercury Marine 25-30 HP 4-Stroke outboards (serial number 0R051710 and above) and a range of Tohatsu/Nissan 25-30 HP 4-Stroke outboards. It provides all the necessary components for a complete overhaul of your outboard's cooling system circulation pump.

This assembly is a direct replacement for Mercury part numbers 853792A07, 853792A1, and 853792T01, as well as Tohatsu/Nissan part number 361873220.

• Installation Type: Direct replacement
• Core Function: Restores cooling system water circulation
• Compatible Engine Types: 4-Stroke

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.

Confirm your engine model/year in the table below.

Mercury Marine

Tohatsu/Nissan

Technical Specifications

Package Contents

• 1 x Water Pump Impeller
• 1 x Metal Gasket with holes
• 1 x Dark Grey Gasket
• 1 x Metal Retainer with slot
• 4 x Mounting Bolts

Installation Guide

1. Safety First: Disconnect the battery and remove the spark plug wires.
2. Access the Lower Unit: Drain the gearcase oil. Unbolt and carefully remove the lower unit from the outboard's driveshaft housing.
3. Open the Water Pump Housing: Locate the water pump assembly on top of the lower unit. Unscrew the bolts securing the housing cover.
4. Remove Old Components: Take note of the orientation of the old parts. Remove the housing, old gaskets, wear plate, and the impeller. You may need to use pliers to pull the old impeller off the driveshaft.
5. Clean and Inspect: Thoroughly clean all surfaces of any old gasket material or debris. Inspect the housing and wear plate for scoring, warping, or damage. Replace if necessary.
6. Install New Impeller: Lightly lubricate the inside of the pump housing. Slide the new impeller onto the driveshaft, rotating the shaft clockwise to bend the vanes into the correct position.
7. Reassemble Kit Components: Install the new gaskets, plates, and seals included in your kit, ensuring each is properly seated.
8. Secure Housing: Re-install the water pump housing and tighten the bolts to the manufacturer's recommended torque specifications.
9. Reattach Lower Unit: Re-install the lower unit, ensuring the driveshaft, shift shaft, and water tube are correctly aligned.
10. Final Checks: Refill the gearcase with fresh oil. Reconnect the battery and spark plug wires.
11. Test Operation: Start the engine in a test tank or with a water flusher attached. Immediately check for a steady stream of water from the "telltale" outlet, which indicates the pump is circulating water correctly.

Troubleshooting & FAQ

Q: How do I confirm this impeller kit fits my specific engine?

A: The best way is to match your engine's serial number or model/year against the compatibility tables on this page. For Mercury engines, ensure your serial number falls within the specified range (e.g., "0R106999 and above"). Cross-referencing your old part number with the OEM numbers listed (853792A07, 361873220) is also a reliable method.

Q: What are the signs of a failing water pump impeller?

A: Common signs include a weak or non-existent water stream from the telltale outlet, engine overheating alarms, or a noticeable decrease in engine performance. Visually, a worn impeller will have cracked, brittle, or permanently curved vanes.

Q: How often should I replace my outboard's impeller?

A: As a general maintenance rule, it is highly recommended to inspect your impeller annually and replace it every 1-2 years or every 100-200 hours of operation, whichever comes first. This interval should be shortened if you frequently operate in sandy, silty, or saltwater conditions.

Q: Is this an OEM part?

A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?

A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?

A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out 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.