SKU: 37509561041

878408A1 Power Trim & Tilt O-Ring Repair Kit for Mercury V6 135-300HP | JLM Marine

$42.99 $47.77
Save 10%
No.2 Bestseller on lamcf.fr >

Pay in installments of $11.94 with ShopPay, AfterPay and Klarna

Shipping Estimate
USA
  • USA
  • CAN

Ships within 48 hours · Estimated delivery Aug 21 - Aug 26

Promo Codes Available:

For Your Every Summer RSVP, with Code: SUMMER15

Description

878408A1 Power Trim & Tilt O-Ring Repair Kit for Mercury V6 135-300HP | JLM MarinePower Trim & Tilt O Ring Repair Kit for Mercury V6 135 300HP This premium Power Trim & Tilt O Ring Repair Kit is engineered for Mercury and Mariner V6 outboard motors ranging from 135HP to 300HP (1998 and newer). It ensures reliable hydraulic sealing and prevents fluid leaks in your power trim cylinder, restoring smooth tilt and trim operation. This kit directly replaces OEM part numbers 878408A1, 878408A 1, 25 878408A1, and 8M0142341. Upgraded with

Power Trim & Tilt O-Ring Repair Kit for Mercury V6 135-300HP

This premium Power Trim & Tilt O-Ring Repair Kit is engineered for Mercury and Mariner V6 outboard motors ranging from 135HP to 300HP (1998 and newer). It ensures reliable hydraulic sealing and prevents fluid leaks in your power trim cylinder, restoring smooth tilt and trim operation.

This kit directly replaces OEM part numbers 878408A1, 878408A 1, 25-878408A1, and 8M0142341. Upgraded with high-grade Viton and Urethane seals, it provides a superior, long-lasting solution compared to standard factory seals that often degrade over time.

  • Comprehensive O-Ring kit for power trim and tilt cylinder rebuilds
  • Fits Mercury V6 135-300HP, Verado 4-Cyl, and Gen 3 engines (1998 & UP)
  • Manufactured with premium Viton and High-Grade Urethane for maximum durability

Part Number Cross-Reference

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

Brand Part Number
Mercury OEM 878408A1, 878408A 1, 878408A01, 25-878408A1
Mercury (Superseded) 855998A10, 855998A11, 8M0142341
Sierra Marine 18-2682 (Reference)
Aftermarket FSM030, FSM010, 811612A, 335-250, REC878408A1

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 / Series Rated HP Engine Type Year Range
Mercury / Mariner V6 Outboards 135 - 250 HP V6 2-Stroke / EFI 1998 and UP
Mercury Gen 3 Outboards 135 - 250 HP V6 2001 and UP
Mercury DFI / Optimax / Pro XS 135 - 300 HP 2.5L & 3.0L V6 2000 - 2018
Mercury Verado 135 - 200 HP 4-Cylinder 4-Stroke 2006 - 2014
Mercury Jet Drive 110 HP 6-Cylinder 2000 - 2005

Technical Specifications

Specification Value
OEM Number 878408A1
Replaces 878408A1, 25-878408A1, 855998A11, 8M0142341
Application Power Trim & Tilt Cylinder Seal Repair
Material Viton & High-Grade Urethane
Engine Configuration V6 / 4-Cyl Verado

Package Contents

This repair kit includes all necessary O-rings and seals to rebuild your power trim cylinder (Note: Contains seals for the cylinders only, not the entire assembly):

  • 26x Various O-Rings (Viton / Urethane)
  • 1x Trilobe Pin (OEM 821539)
  • 2x Poppet Assembly
  • 1x Valve Assembly
  • 1x Tilt Wiper Seal & 2x Wiper Seals
  • Manifold Screws & Filter Caps

Installation Guide

  1. Ensure the outboard motor is securely supported and the trim system is depressurized before beginning work.
  2. Remove the power trim and tilt assembly from the engine bracket following your Mercury service manual.
  3. Carefully disassemble the trim cylinders. Take note of the orientation of all internal components.
  4. Remove old seals, O-rings, and wipers. Clean all cylinder walls and grooves thoroughly with a lint-free cloth and appropriate solvent.
  5. Inspect the cylinder walls and rods for scoring, pitting, or corrosion. Replace hard parts if necessary.
  6. Install the new Viton and Urethane seals from the kit. Lightly lubricate all new O-rings with premium power trim fluid before installation to prevent tearing.
  7. Reassemble the cylinders and reinstall the trim unit onto the outboard.
  8. Fill the reservoir with the recommended Mercury Power Trim fluid, bleed the system of air by cycling it up and down several times, and check for leaks.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my Mercury engine?
A: Verify your engine is a V6 (135-250HP) from 1998 or newer, a 2.5L/3.0L DFI/Optimax, or a 4-Cylinder Verado (135-200HP). You can also cross-reference OEM part numbers 878408A1 or 25-878408A1.

Q: Why are my original trim seals leaking?
A: Factory OEM seals from certain eras are known to soften and degrade over 5-10 years of use in harsh marine environments. This kit uses upgraded Viton and Urethane materials designed to resist degradation and outlast the originals.

Q: Does this kit rebuild the entire trim and tilt unit?
A: No, this specific kit (878408A1) contains the O-rings and seals for the cylinders only. It does not contain all the O-rings for the entire valve body/manifold assembly.

Q: Is this an OEM or aftermarket part?
A: This listing is a premium aftermarket replacement part. We build to exceed OEM specifications using superior-grade Viton and Urethane 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: 37509561041

Discover Niche Categories That Outsell

Top-Converting Item to Boost Your Average Order

4.2 ★★★★★
Based on 20 reviews
Sort
Highest Rating
Newest First
Oldest First
Product Reviews
P
Verified Purchase
Peter D.
Draper, US
★★★★★ 5
"The" Standard for All-Weather Notebooks
Color: Black, Size: 3 Pack
This Rite In The Rain notebook is the leading brand for a reason. It works exactly as advertised, performing flawlessly in conditions where a normal notebook would be ruined. I’ve used alternative brands in the past and ran into issues with the paper or ink smudging, but I’ve had no such problems with this notebook. The weatherproof paper and sturdy cover ensure that your notes stay safe and legible, no matter the conditions.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on August 21, 2025
L
Verified Purchase
Laura Schluns
New York, US
★★★★★ 5
An Amazing product, that works
Color: Green, Size: 1 Pack
I bought the (Rite in the Rain - Green Tactical Note Book (All Weather) for my line of work with the sheriffs department. And when your note taking can be the difference between your job and keeping someone bad off the streets, it's important to ensure that your notes are going not only to last, but handle all situations (like weather). I recieved my notebook about 5 days ago, and decided to give it a try, First I noticed it looked and almost felt like ordinary paper, but with a more thick quality with it. I began to write simple phrases on the first page with a variety of writing utensils, I tried an ordinary pen, a pencil, a 0.5mm pen and pencil, ballpoint pens, and so on. Then I tore out the first page which was as easy if not easier than an ordinary notebook. I took it over to the sink area and began to run water on the paper, for about 2 minutes the water beaded off the paper with ease, i turned the water off and examined the paper, it was only wet on the surface, i wiped the excess water off and perfect, it felt like the original paper with no signs of any water damage. This is a great product for someone who may work in an outdoor environment or just near water I highly Recommend this product to anyone in the market for a notebook that not only has quality but is resistant to everyday situations, thanks (Rite in the Rain) for making a great product. If you have any questions or comments or conserns please use the comment section below, and I will answer as swiftly as I can Thanks.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 17, 2012
F
Verified Purchase
Fish
Grantham, US
★★★★★ 5
Good quality
Color: Tan, Size: 6 Pack
These are very good quality. The only notepad that can stand up to extreme conditions. The 4X6 is the perfect size for back pockets.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on August 12, 2025
J
Verified Purchase
Jwadswor
New York, US
★★★★★ 5
This is a Great Watch!
Color: Green, Style: Modern
Awesome watch!! I bought this watch three weeks ago, and I couldn't be more pleased. I needed a watch with a rubber strap. I work with natural stone, and the majority of the tools we use are water tools. I have never owned a watch with a rubber bracelet before this one, and I am very impressed with how comfortable and easy to keep clean it is. I also enjoy the green, orange and black color scheme. This watch has held up great! I shower with, swim, and work in this watch. I am very rough on this thing, and so far it has handled everything well. The solar feature works great! I received it with a full charge, and after the first day it dropped to medium. I placed it in a window seal for a few hours, and it has held a full charge ever since. I enjoy how lightweight and comfortable this watch is as well. It fits well on my medium sized wrist, it is not too big and bulky, but it is not a small watch either. The large numbers on the dial glow, and the digital screen has an illumination light. The digital display is kind of small, but the analog is very easy to read. The Arabic numerals are very large making them easy to read. This watch has all the great features you would want from a digital watch, with the style of an analog watch. All of the digital features are easy to use. I have always worn, and preferred an analog watch, so the : stopwatch, dual timers, and alarms have all been nice to have. The watch comes with a manual, but it is kind of small and hard to read. I would recommend going to Casio's web page where you can view, save, and print a much larger and easier to read version of the manual. The manual is easy to understand, and the watch is easy to program. This is my first Casio, and I could not be more pleased! I'm now thinking about investing in a G-Shock. The digital features on this watch have made me want one with a larger digital display, so I am wanting to buy a digital only watch. The GW6900-1 looks cool and is atomic and solar! It is also a good buy at around $79.00 on amazon right now. Check it out too, if you think you want a full screen digital instead, and don't mind spending a little extra cash.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 11, 2014
J
Verified Purchase
Joe Simpson
Lexington, US
★★★★★ 5
Not a G but just as good IMO
Color: Green, Style: Modern
Solar, mineral crystal, excellent color (mine is green) - almost the perfect watch. Big but light and comfortable. Good for old person eyes, easy to read. The digital window is hard for me to read but "its there". Its not officially a G-Shock but its touch, Solar and waterproof so I am just as happy and the price...$$ is right.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 9, 2025

recommand products

Peach and gold BANGLE SET
45.00
Coral BANGLE SET
45.00
Stade de Rugby Dax
23.00
Sunf 145/70-6 145/70X6 Atv Utv Tires 6 Pr Tubeless A014 [Set Of 2]
52.95
Saint-Tropez en famille
23.00