SKU: 91825021372

Water Pump Repair Kit – Fits Yamaha 2-Stroke 40-50HP (Replaces 6H4-W0078-00-00, Sierra 18-3429)

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Description

Water Pump Repair Kit – Fits Yamaha 2-Stroke 40-50HP (Replaces 6H4-W0078-00-00, Sierra 18-3429)Water Pump Repair Kit Fits Yamaha 2 Stroke 40 50HP (Replaces 6H4 W0078 00 00, Sierra 18 3429) This water pump repair kit is designed for select Yamaha 2 stroke outboard engines, including 40HP (19841994), 50HP (19841987), Pro Series 50HP (19871990), and P50 models (19951996). It provides the necessary components to overhaul your engine's cooling system for reliable performance. This kit serves as a direct replacement for Yamaha part numbers 6H4 W0078

Water Pump Repair Kit – Fits Yamaha 2-Stroke 40-50HP (Replaces 6H4-W0078-00-00, Sierra 18-3429)

This water pump repair kit is designed for select Yamaha 2-stroke outboard engines, including 40HP (1984–1994), 50HP (1984–1987), Pro Series 50HP (1987–1990), and P50 models (1995–1996). It provides the necessary components to overhaul your engine's cooling system for reliable performance.

This kit serves as a direct replacement for Yamaha part numbers 6H4-W0078-A0-00, 6H4-W0078-00-00, and 6H4-W0078-01-00. It is also an aftermarket equivalent to Sierra 18-3429. For a kit that includes the housing, reference Sierra part 18-3408.

  • Installation Method: Installs as a direct OEM-style replacement.
  • Engine Compatibility: Designed for marine 2-stroke outboard cooling systems.
  • Complete Kit: Includes a new impeller, gaskets, wear plate, insert cup, water seal, and other hardware required for a standard rebuild.

Part Number Cross-Reference

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

Brand Part Number Notes
Yamaha 6H4-W0078-A0-00
Yamaha 6H4-W0078-00-00
Yamaha 6H4-W0078-01-00
Sierra 18-3429 Base kit without housing.
Sierra 18-3408 Kit with housing included.

Compatible Engine Models

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

Brand Model Rated HP Stroke Years OEM Part No.
Yamaha Outboard 40 2-Stroke 1984-1994 6H4-W0078-00-00, 6H4-W0078-01-00, 6H4-W0078-A0-00
Yamaha Outboard 50 2-Stroke 1984-1987 6H4-W0078-00-00, 6H4-W0078-01-00, 6H4-W0078-A0-00
Yamaha Outboard Pro Series 50 50 2-Stroke 1987-1990 6H4-W0078-00-00, 6H4-W0078-01-00, 6H4-W0078-A0-00
Yamaha Outboard P50 50 2-Stroke 1995-1996 6H4-W0078-00-00, 6H4-W0078-01-00, 6H4-W0078-A0-00

Technical Specifications

Specification Value
Product Type Water Pump Repair Kit
Installation Direct OEM replacement
Housing Material Not included in base kit (housing sold separately)
Other Technical Attributes Compatible with marine 2-stroke outboard cooling systems

Package Contents

  • 1 x Water Pump Impeller (6H4-44352-00)
  • 1 x Woodruff Key (90280-03M03-00)
  • 1 x Cartridge Outer Plate (663-44323-00)
  • 1 x Insert Cup (663-44322-00)
  • 1 x Gasket (663-44315-A0)
  • 1 x Gasket (663-44316-A0)
  • 1 x Gasket (663-44324-A0)
  • 1 x Water Seal (93101-23070-00)
  • 2 x Bolt (97095-08045-00)
  • 2 x Bolt (97095-08045-00)

Installation Guide

  1. Safety First: Disconnect the battery and ensure the engine is in a secure, stable position.
  2. Drain Gear Lube: Place a drain pan under the lower unit and remove the upper and lower gear lube drain screws to drain the oil.
  3. Remove Lower Unit: Remove the mounting bolts securing the lower unit (gearcase) to the midsection. Carefully lower it to access the water pump.
  4. Disassemble Pump: Unscrew the bolts on the water pump housing and lift it off. You may need to gently pry it.
  5. Remove Old Components: Take out the old impeller, wear plate, gaskets, and seals. Note their orientation for correct reassembly.
  6. Clean Surfaces: Thoroughly clean all mating surfaces, removing any old gasket material or corrosion.
  7. Install New Parts: Place the new gasket and outer plate on the gearcase. Install the new insert cup into the housing.
  8. Install Impeller: Slide the new Woodruff key onto the driveshaft and install the new impeller, turning the driveshaft clockwise to bend the vanes correctly.
  9. Reassemble Pump: Apply a light coat of marine grease to the inside of the insert cup. Slide the housing down over the impeller and secure it with the new bolts and gaskets.
  10. Reattach Lower Unit: Guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube align correctly. Fasten the mounting bolts.
  11. Refill Gear Lube: Fill the lower unit with fresh gear lube from the bottom drain hole until it seeps out of the top hole, then reinstall both screws.
  12. Test Operation: Securely attach a water source ("ear muffs") and run the engine to check for proper water flow and no leaks.

Troubleshooting & FAQ

How do I confirm this kit fits my engine?
First, check the "Compatible Engine Models" table on this page. Your engine's model, horsepower, and year range should be listed. Second, compare the part numbers in the "Part Number Cross-Reference" table to your existing part or service manual. Finally, visually compare our product photos with your old parts before ordering.

What are the signs that my water pump needs to be replaced?
Common signs of a failing water pump include the engine overheating, a weak or inconsistent stream of water from the "telltale" outlet, and visible cracking or deterioration of the impeller vanes upon inspection.

How often should I replace my water pump impeller?
For preventative maintenance, it is recommended to replace your impeller every 1-2 years or every 100-200 hours of operation, depending on usage conditions (e.g., saltwater vs. freshwater). Always consult your engine's service manual for specific intervals.

Does this kit include the water pump housing?
No, this is a basic repair kit that does not include the metal water pump housing. This kit matches Sierra 18-3429. If your housing is scored, warped, or cracked, you should purchase and install a new one separately. The kit that includes a housing is typically equivalent to Sierra 18-3408.

OEM vs. Aftermarket?
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.

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

What is your warranty and return policy?
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: 91825021372

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Jessika
Carnegie, US
★★★★★ 4
Definitely worth the read!
Format: Kindle
After taking a deep breath and taking in that wicked twist of an ending, I have finally composed myself. My first thought when I started this book was that I love Reyna's character. I was intrigued by her connection with her familiar and the Ruin that is plaguing her land. It came as no surprise that she took her sister's place in an attempt to protect her. When they reach the Air Court everything slows down. This is where it was iffy for me. First of all, I like multiple POV's in books however 7 is a bit much. It starts to interrupt the story line. I felt like I was finally making progress connecting with one character, then it was switched to another person. I felt they all had necessary or pertinent information but not necessarily were they all POV worthy. The only other thing that annoyed me was that Reyna constantly was " trapped." She would rush off without thinking, only to need rescuing. She is brilliant in a fight, but she really doesn't think through anything. Lorcan is amazing. I know he might be on the "bad" list, but his background is so interesting. Eislyn(Reyna's sister) is really so sweet, but calculating. I enjoyed her and Thane's dialogue. The author did an amazing job with the imagery in this book. Everything was so detailed it was easy to fall into the scene. I love unexpected twists and while part of the ending I expected, I wasn't expecting how it took place. All in all, I found it very entertaining and I am very invested in continuing this series. Favorite quotes: "The truth may be twisted but never false." "Who was she if she was not the enemy of the Air Court? What was her purpose of she no longer has that?" "In a war-torn land, love was always a lie."
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 4, 2020
K
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KAB
West Palm Beach, US
★★★★★ 5
Great Read!!! Great story!!!
Format: Kindle
The series is long, but Ms. Wolfhart does a fantastic job of weaving this tale while bringing so much to the characters. Surprises and plot twists along the way to keep you intrigued. There is some graphic sex, but is no way the focal point. Grammar was excellent (a rare find with a lot of self publishers) with only a few noted errors. I rarely give 4 stars, let alone 5.
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Reviewed in the United States on April 30, 2021
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Elisa
Pawtucket, US
★★★★★ 3
Sadly, DNF
Format: Kindle
I read this thru KU. I LOVED the synopsis. And then I began reading... and it was a DNF at 68% after picking it up and putting it down several times because I really loved the main female character. *****SPOILERS***** Pros: The world is unique, intriguing and fun. The primary female character is bad-a** but not a b*tech or a mary sue. The primary female has depth. I really want to know what happens to her even tho it's been weeks and I don't remember her name. The villains to the point I read are pretty good -- an ever present threat of mysterious and possibly many culprits. Cons: Way, way too many points of view. I stopped counting at 7. It's the prime reason why I don't care about most of the characters or remember their names even when I like them. There's just too many points of view so almost none of the characters have enough book space for the author to properly develop them. This literally killed the book for me. Actually it killed my desire to read. For weeks. The main male is more villain than hero. He agreed to marry the main female then locks her up & eschews her for her sister, all while bad mouthing her as unfit to rule when he never spent any time with her getting to know her. He is actually unfit to rule as he is blind to the woes of his own kingdom and starts off a peace mission to secure a ceasefire through marriage by murdering an inn full of people in her country for no real reason. Plus, he constantly makes promises he does not keep. And it's gross of him to pine for the sister behind the main female's back. ***** As much as I really wanted to see what happened to the main female character, it wasn't enough for me to keep trying to slog thru this book. There was a lot of potential here that just fell short. Hence, 3 stars.
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Reviewed in the United States on June 19, 2021
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MaryBeth K
Birmingham, US
★★★★★ 5
Fae Courts with High Intrigue
Format: Kindle
This book is one that just builds and builds and then surprises you to no end. You may think you know the villains and then you are jolted in another direction. Princess Reyna is a real gem, strong of character, a fierce fighter, and loyal to her family and kingdom. Just when you think she and Lorcan, well you know, the plot is flipped. Can't wait to see where this goes in book two.
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Reviewed in the United States on July 7, 2023
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Kindle Customer Maureen
Boise, US
★★★★★ 4
Slow, sorry but good
Format: Kindle
This was a slow moving book. Lots of character pov chapters, lots of superfluous descriptions and endless courtly appearances stalled this book to start. Once you get into the heart of the story, it takes off. Before you know it the book is done. My favorite character is Reyna. She is so strong. She is true to herself. She gets into a lot of trouble with her headstrong ways but it's entertaining. I have high hopes for Lorcan. He is honorable to a fault. Thane had turned out to be better than I thought but i still don't like him. Eislin is useless. Great plot twists at the end. I'm looking forward too book 2.
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Reviewed in the United States on June 6, 2020

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