SE116, UPPER 1.47 (Replaces Mercruiser Gen II)

Q: Is the SE116, UPPER 1.47 compatible with all Mercruiser lower units?

No, the SE116 Upper 1.47 is designed for Mercruiser Alpha One Gen II only. It is not compatible with Gen I or Bravo drives.

Q: How do I know if my current upper unit needs replacement?

Signs include noise under load, metal shavings in oil, and oil leakage. Have your drive inspected if these symptoms appear.

Q: How long does it take to install the SE116 Upper 1.47?

Installation typically takes 2–3 hours with proper tools. It is DIY-friendly for those with mechanical experience.

Q: Can I use the SE116 in saltwater conditions?

Yes, the SE116 is saltwater-safe. Always rinse and maintain the drive to extend its service life in marine environments.

Q: What warranty does the SE116 come with?

It includes a 3-year no-fault warranty, offering unmatched protection even in cases of user error.

Posted by

nikhil

On July 27, 2025

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SE116, UPPER 1.47 (Replaces Mercruiser Gen II) for marine

Introduction

When it comes to reliable marine propulsion, your boat’s sterndrive system is the backbone of performance. The SE116, UPPER 1.47 is a top-tier replacement for the legendary Mercruiser Alpha One Gen II, built for exceptional durability and power transmission. Designed with precision engineering and robust materials, this upper unit delivers unmatched efficiency and smooth operation, ensuring your time on the water is hassle-free. Whether you’re upgrading a worn-out component or building a new drive system, the SE116 Upper 1.47 is the smart choice for any marine engine enthusiast.

Specifically crafted for marine environments, this unit matches the OEM quality without the hefty price tag, making it one of the best SE116 upper marine options in the market.

SE116, UPPER 1.47 (Replaces Mercruiser Gen II) for Boats & Marine Engines

Overview / What Is SE116, UPPER 1.47?

The SE116, UPPER 1.47 is a direct aftermarket replacement unit for the Mercruiser Alpha One Gen II upper gearcase. It is used in boats and marine engines that require a gear ratio of 1.47:1, suitable for specific engine horsepower ranges and boat types. Manufactured by SEI (Sterndrive Engineering, Inc.), this unit ensures high compatibility with OEM specifications while offering better value for money.

This upper gear unit is primarily responsible for transmitting engine power to the lower gearcase, ensuring optimal propulsion and control. It features hardened gears, precision-fit components, and an anodized aluminum case designed to withstand the marine environment.

How to Install SE116 Upper 1.47 on Your Boat

Installing the SE116 upper marine gearcase is a straightforward task for experienced boat mechanics or DIY marine enthusiasts with the right tools. Here’s a simplified installation guide to help:

Ensure compatibility with your lower unit and engine setup (Alpha One Gen II only).
Drain old gear oil and disconnect the current upper unit.
Clean all sealing surfaces and inspect gaskets.
Install the SE116 Upper 1.47 with new gaskets and torque bolts as specified.
Refill with high-quality marine-grade gear oil.

Pro Tip: Use a pressure tester to ensure there are no leaks before first use. Always break-in the new upper with care.

Benefits of Using SE116 Upper 1.47 for Marine Engines

Choosing the SE116 Upper 1.47 means choosing performance, compatibility, and reliability. Here are some of the most important benefits boaters love:

OEM Compatibility: Seamless replacement for Mercruiser Alpha One Gen II.
Cost-Effective: High-performance alternative to Mercruiser at a fraction of the cost.
Durability: High-strength gears and marine-grade aluminum housing.
Warranty: Backed by SEI’s 3-year fault-free warranty.

Whether you’re planning long offshore trips or lake cruising, the SE116 is the perfect companion to boost your boat’s performance and reduce downtime.

Maintenance Tips

Keeping your SE116 upper marine drive in peak condition involves consistent inspection and routine maintenance. Follow these essential maintenance tips to ensure long service life:

Check and change gear oil every 100 hours or at least once per season.
Inspect upper seals and vent holes for water intrusion.
Grease all fittings and prop shaft regularly.
Flush with freshwater after every saltwater trip.
Store unit upright in off-season to avoid oil migration.

Note: Failure to follow break-in procedures can void warranties and damage internal gears. Always follow the manufacturer’s guide.

Expert Advice and Pro Recommendations

Marine technicians consistently recommend the SE116, UPPER 1.47 for both casual and professional use due to its reliability, easy installation, and high torque output. When choosing an upper drive unit, ensure your engine horsepower, gear ratio, and compatibility with lower unit match precisely.

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Common SE116 Troubleshooting and Fixes

Even the most durable marine parts may encounter wear and tear. Here are some common issues and fixes related to the SE116:

Noise under load: May indicate improper gear break-in. Drain oil and check for metal shavings.
Leaking oil: Check for failed gaskets or sealant misuse during installation.
Overheating: Likely caused by lack of oil or poor ventilation. Check oil levels and passage obstructions.

Using genuine marine-grade lubricants and performing routine inspections can help avoid these problems entirely.

SE116 Upper 1.47 Cost and Durability Analysis

The SE116 is not only affordable but built to last. Compared to OEM Mercruiser units, it costs up to 40% less while offering similar performance benchmarks. With an average lifespan of over 1,000 engine hours when maintained properly, it’s one of the best marine upper gearcase options available today.

Its anodized housing protects against corrosion and marine biofouling, while the stainless-steel gears resist wear under extreme torque conditions. It’s a long-term investment in your boat’s performance and reliability.

Detailed FAQ Section

1. Is the SE116, UPPER 1.47 compatible with all Mercruiser lower units?

No, the SE116 Upper 1.47 is specifically designed to fit Mercruiser Alpha One Gen II lower units. It is not compatible with Gen I or Bravo series units. Always check your existing unit’s serial number, gear ratio, and application requirements before purchase. Compatibility is critical to ensure seamless function and avoid premature wear or malfunction.

2. How do I know if my current upper unit needs replacement?

Signs include metal shavings in the gear oil, whining or grinding noise while accelerating, excessive play in the prop shaft, or oil leaking from the upper drive. If you’ve experienced poor performance or have difficulty maintaining power, it’s time to inspect the upper gearcase. A qualified marine mechanic can pressure test and diagnose internal gear or bearing wear. Replacing it with an SE116 upper marine unit restores full performance.

3. How long does it take to install the SE116 Upper 1.47?

Installation typically takes 2–3 hours for experienced marine technicians. DIY enthusiasts with moderate mechanical skills and the right tools can also perform the installation. Just make sure to follow proper torque specifications, use fresh gaskets, and refill the unit with high-grade gear oil. SEI provides a helpful video series that walks through the entire installation process step by step.

4. Can I use the SE116 in saltwater conditions?

Yes, the SE116 Upper 1.47 is engineered to withstand saltwater conditions. The unit is anodized for extra corrosion protection, and all components are marine-rated. However, it’s crucial to rinse your drive thoroughly with freshwater after each saltwater use and perform more frequent inspections. Saltwater environments are harsh on marine gear, so following a proactive maintenance routine is essential to maximize the unit’s lifespan.

5. What warranty does the SE116 come with?

The SE116 Upper 1.47 comes with an industry-leading 3-year, no-fault warranty from SEI. This means even if the damage results from user error or misuse, SEI will repair or replace the unit. Few marine part manufacturers offer such robust coverage. It’s a testament to the confidence they have in their engineering and manufacturing processes. Always retain your receipt and warranty documentation to ensure quick service if needed.

Conclusion

The SE116, UPPER 1.47 is a game-changer for marine enthusiasts seeking performance, reliability, and affordability. It’s a smart replacement for the Mercruiser Alpha One Gen II upper unit and comes with a solid warranty for peace of mind. With proper care and installation, it will power your adventures for years to come. From weekend fishing trips to offshore cruising, this upper gear unit is the dependable choice.

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For more helpful marine maintenance guides, check out our article on Amita 3 – Evinrude/Johnson (9.25 x 11″) Solas RH Propeller, 2111-093-11.