SKU: 89843103174

Water Pump Repair Kit – Fits Mercury/Mariner 25–50HP (Replaces 821354A2)

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Description

Water Pump Repair Kit – Fits Mercury/Mariner 25–50HP (Replaces 821354A2)Water Pump Repair Kit Fits Mercury Mariner 2550HP (Replaces 821354A2) This water pump repair kit is designed for Mercury Mariner 2550HP 2 Stroke and 4 Stroke outboard engines. It provides the essential components needed to restore the performance and reliability of your engine's cooling system. This kit is a direct replacement for Mercury Mariner part numbers 821354A2 and 821354A1, as well as aftermarket parts from Sierra (18 4531), GLM (12045), and

Water Pump Repair Kit – Fits Mercury/Mariner 25–50HP (Replaces 821354A2)

This water pump repair kit is designed for Mercury/Mariner 25–50HP 2-Stroke and 4-Stroke outboard engines. It provides the essential components needed to restore the performance and reliability of your engine's cooling system.

This kit is a direct replacement for Mercury/Mariner part numbers 821354A2 and 821354A1, as well as aftermarket parts from Sierra (18-4531), GLM (12045), and SEI (3219).

  • Installation: Designed for a direct fit, replacing the original OEM components without modification.
  • Complete Kit: Includes a new impeller, drive key, face plate, gaskets, and seals for a comprehensive service.
  • Engine Health: Restores proper cooling system function to prevent overheating and potential engine damage.

Part Number Cross-Reference

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

Brand Part Number
Mercury/Mariner 821354A2
Mercury/Mariner 821354A1
Sierra 18-4531
GLM 12045
SEI 3219

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.

Brand Model Rated HP Stroke OEM Part No. Notes
Mercury/Mariner 25HP 25 2-Stroke 821354A2
Mercury/Mariner 25HP 25 4-Stroke 821354A2 Serial numbers: 0G531301 and up
Mercury/Mariner 30HP 30 2-Stroke 821354A2
Mercury/Mariner 30HP 30 4-Stroke 821354A2 Serial numbers: 0G053314 and up
Mercury/Mariner 30HP Jet 30 821354A2 Serial numbers: 0G590000 to 0T408999, 9973100 to 0P153499
Mercury/Mariner 40HP 40 2-Stroke 821354A2
Mercury/Mariner 40HP 40 4-Stroke 821354A2 Serial numbers: 0G531301 and up (2 cyl), 0G590000 and up (3 cyl)
Mercury/Mariner 45HP 45 821354A2
Mercury/Mariner 50HP 50 2-Stroke 821354A2
Mercury/Mariner 50HP 50 4-Stroke 821354A2 Serial numbers: 0G590000 and up (3 cyl)

Technical Specifications

Specification Value
Product Type Water Pump Repair Kit
Installation Direct OEM replacement
Other Technical Attributes OEM-quality replacement parts

Package Contents

  • 1 x Water Pump Impeller
  • 1 x Drive Key
  • 1 x Face Plate
  • 1 x Upper Gasket (Replaces OEM 27-822189)
  • 1 x Lower Gasket (Replaces OEM 27-822217)
  • 2 x Washer (Replaces OEM 12-866451)
  • 1 x Water Tube Seal

Installation Guide

  1. Disconnect the battery and shift linkage before beginning.
  2. Remove the lower unit mounting bolts and carefully lower the gearcase from the engine.
  3. Unbolt and remove the old water pump housing to access the impeller.
  4. Remove the old impeller, gaskets, and wear plate, noting the original orientation of the impeller vanes.
  5. Thoroughly clean all mounting surfaces of any old gasket material or debris.
  6. Install the new lower gasket, wear plate, and drive key onto the driveshaft.
  7. Slide the new impeller onto the driveshaft, turning the shaft clockwise to bed the vanes correctly inside the housing.
  8. Install the new upper gasket and secure the pump housing, torquing bolts to manufacturer specifications.
  9. Apply a suitable sealant to the new water tube seal and install it.
  10. Carefully reinstall the lower unit, ensuring the water tube, driveshaft, and shift shaft are correctly aligned.
  11. Reconnect the shift linkage and battery connections.
  12. Crucially, test the engine using a water supply (flushing attachment or in water) to verify proper water flow from the telltale outlet.

Troubleshooting & FAQ

Q: How do I know if this water pump kit will fit my Mercury engine?

A: This kit fits most Mercury/Mariner outboards in the 25-50HP range. The most reliable way to confirm fitment is to match your engine's serial number to the ranges listed in the "Compatible Engine Models" table above. If your model and serial number are listed, the kit will fit.

Q: What are the common signs that my water pump needs to be replaced?

A: Key symptoms include the engine overheating (especially at idle or low speeds), a weak or non-existent water stream from the "telltale" outlet, or finding brittle, cracked, or deformed impeller vanes during an inspection.

Q: How often should I replace my water pump impeller?

A: For preventative maintenance, we recommend replacing the water pump impeller and gaskets every 1-2 years or every 100-200 hours of use. Service intervals should be shorter if operating frequently in saltwater or silty/sandy conditions.

Q: OEM vs. Aftermarket?

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.
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 89843103174

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Let me just get this out of the way now the soap itself smells decent, nothing wrong there. I only wish I got another cent. Not that this one smells bad it’s just it wasn’t my cup of tea. I’m mostly disappointed about the size because I’ve been through this before. The soaps themselves are not big enough to fill out the box as you can spot in some of the pictures and video. I honestly feel like the soap size was different in the pictures of the customer reviews that I saw. Each bar may last me a week and a half and that’s with a soap saver. To be honest, the box that it came in would fit two decent size soaps if they filled out the box.
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I've read a number of good books on the Guadalcanal campaign, and always thought that "Neptune's Inferno" by Hornfischer was the absolute best. I was wrong. Although Hornfischer does a superb account of the Navy and its travails and triumphs, Inferno doesn't delve deeply into the Marine (and Army) land battles. This book does both. Moreover, it provides a continuous timeline of both, and does so in such a way that the reader better understands both as related actions. For instance, I was never really aware that for the first three and a half months the Americans controlled the seas during daylight, and the Japanese at night (sounds a little like Viet Nam). The November 13 sea battle between Americans and Japanese -- in which US cruisers took on Japanese battleships and two American admirals died -- was in fact a clash of a major last ditch effort by the Japanese to reinforce their troops and destroy Henderson Field, which would have allowed them to control the seas both day and night. By that time there had been multiple bloody battles ashore between the Marines and Japanese, with the balance favoring the Marines, but if the Japanese had wrested control of the airfield and seas that would have been old history. The book includes a good view from the Japanese perspective, and some little known historical tidbets as well, e.g., Guadalcanal received its name from the Spanish home town of a ships officer who accompanied Spanish explorer Don Alvaro Medana, who discovered the island during a 1568 expedition to discover the fabled King Solomon's gold mines. Who knew? :-) Bottom line: I highly recommend this book, both for its balanced coverage of the entire campaign, land and sea, and even more for its integrated narrative -- you know what was taking place (or had taken place) on almost a day-by-day basis, which allows the reader to fully appreciate how actions ashore influenced those at sea, and vice versa. IMO, a must read, even for those who thought (like me) that they knew it all!
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Reviewed in the United States on October 12, 2017
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Jeffrey T. Munson
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★★★★★ 5
The Island Of Death
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On August 7th, 1942, American Marines stormed ashore on Guadalcanal. What lay before them was a six-month odyssey of fighting against the best of what the Japanese had to offer. In this fine book, author Joseph Wheelan describes the battle that turned the tide in the Pacific War. The Japanese had started construction of an airfield on Guadalcanal. If completed, Japanese aircraft would be able to harass American convoys and threaten Australia. The Americans seized the airfield and eventually, planes from the Cactus Air Force began attacking the Japanese. Throughout the book, the reader learns about all phases of the Guadalcanal campaign, including the battles of Alligator Creek and Bloody Ridge. On the sea, the Americans and Japanese slugged it out at Savo Island, as well as the great naval battles of November, 1942. Names such as Chesty Puller, John Baslone, "Archie" Vandegrift, Joe Foss, and "Bull" Halsey became household names in the United States. Each side lost many men, ships, and planes, but the tenacity and, finally, the industrial might and the ability to rapidly replace losses, led the Americans to victory. Never again would the Japanese regain the offensive in the Pacific War. "Midnight in the Pacific" is a very good book, and the author has done a good job of describing all of the main points of the battle. Each chapter is broken down into a single month's worth of action, and the narrative is well-written. Highly recommended.
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Reviewed in the United States on September 25, 2017
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Laurence J. Rusiecki
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Good Narrative History
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