MERCURY 803373 Impeller Kit

( Manufacturer Part Number: 803373 ), ( Part Type: Impeller ), ( Country Of Origin: United States )

Review MERCURY Oem Impeller Kit

The **Mercury 803373 Impeller Kit** is a high-performance, precision-engineered component designed to maximize the efficiency and power output of Mercury outboard motors, particularly those in the 90 250 horsepower range. This impeller kit is crafted from durable, corrosion-resistant materials, ensuring longevity and reliable performance even in the most demanding marine environments. The kit features a meticulously balanced impeller assembly, including a high-strength impeller blade and a robust impeller hub, both of which are engineered to optimize water flow and reduce cavitation. The impeller blades are aerodynamically shaped to enhance thrust while minimizing drag, allowing the motor to deliver superior acceleration and top-end speed. Whether used in fishing boats, speedboats, or performance cruisers, this impeller kit helps maintain optimal engine performance, reduces fuel consumption, and extends the life of the motor by reducing wear on critical components. Installation is straightforward, requiring only basic tools, and the kit includes all necessary gaskets and seals to ensure a secure fit. Ideal for marine enthusiasts seeking to restore or upgrade their Mercury outboard s power and efficiency, this impeller kit is a must-have for anyone looking to get the most out of their vessel.

The **Mercury 803373 Impeller Kit** is designed to replace the stock impeller in Mercury outboard motors, typically for models like the 90 HP, 115 HP, and 150 HP E-TEC and EFI engines. Below is a detailed breakdown of its pros and cons, followed by a conclusion and recommendation.

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### **Pros of the Mercury 803373 Impeller Kit**

1. **Improved Performance and Throttle Response**

The kit includes a high-performance impeller that enhances water flow through the engine, reducing cavitation and improving throttle response. This is particularly noticeable in cold water or when operating at higher RPMs, as the engine breathes better, leading to smoother acceleration and better power delivery.

2. **Better Cooling Efficiency**

The stock impeller may not provide optimal water flow, leading to overheating under heavy loads or in warm water. The upgraded impeller ensures a stronger water pump action, which improves cooling efficiency and reduces the risk of engine damage from overheating.

3. **Compatibility with Performance Modifications**

If you ve installed other performance upgrades (e.g., larger propellers, exhaust modifications, or fuel system tweaks), the Mercury 803373 impeller kit can complement these changes by maintaining proper water flow and pressure, preventing issues like "choking" or poor performance.

4. **Durability and Material Quality**

Mercury s impeller kits are typically made from high-quality materials designed to withstand the demands of marine use. The kit includes gaskets and seals that are engineered to prevent leaks and ensure a secure fit, reducing the likelihood of water ingress into the engine compartment.

5. **Easy Installation**

The kit is designed for straightforward installation, often requiring minimal tools. Mercury provides clear instructions, and the impeller is a direct replacement for the stock part, making it accessible for DIYers or mechanics without specialized equipment.

6. **Cost-Effective Upgrade**

Compared to other performance modifications (e.g., engine swaps or major fuel system upgrades), replacing the impeller is relatively inexpensive. The cost is justified by the noticeable improvements in performance and reliability, especially for those who frequently operate at high loads.

7. **Reduced Cavitation and Pinging**

Cavitation occurs when the engine struggles to pull enough water, leading to metallic pinging noises and potential damage to internal components. The upgraded impeller reduces this risk by ensuring consistent water flow, even under demanding conditions.

8. **Maintenance of Warranty (If Applicable)**

Mercury s performance parts are often designed to work within the manufacturer s specifications, so installing this kit may not void your engine warranty if done correctly. Always check your specific warranty terms to confirm.

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### **Cons of the Mercury 803373 Impeller Kit**

1. **Limited Performance Gains for Stock Setups**

If your boat is already running a stock propeller and other components (e.g., exhaust, fuel system), the performance gains from the impeller kit may be modest. Significant improvements are more noticeable when paired with other upgrades like a larger propeller or a performance exhaust.

2. **Potential for Overcooling in Cold Water**

While the impeller improves cooling efficiency, in very cold water, the increased water flow might cause the engine to run slightly cooler than optimal. This can sometimes lead to condensation issues or minor efficiency losses, though this is rare and usually not a major concern.

3. **Requires Proper Propeller Matching**

Installing a high-performance impeller without matching it with an appropriately sized propeller can lead to issues like excessive RPMs, poor top-end speed, or even damage to the engine. You may need to adjust your propeller size to balance performance and efficiency.

4. **Installation Risks if Not Done Correctly**

Improper installation such as failing to torque bolts to specification or not sealing gaskets properly can lead to leaks, reduced performance, or even engine damage. This risk is mitigated by following Mercury s instructions carefully or having a professional install it.

5. **Not a Universal Fix for All Performance Issues**

If your engine is experiencing problems unrelated to impeller performance (e.g., fuel delivery issues, electrical faults, or mechanical wear), replacing the impeller alone won t resolve those issues. A thorough diagnostic is needed for broader performance problems.

6. **Potential for Increased Noise**

Some users report a slight increase in engine noise due to the impeller s design, though this is usually minimal and not a dealbreaker for most boaters.

7. **Compatibility Concerns for Older or Modified Engines**

While the 803373 kit is designed for specific Mercury models, older engines or those with extensive modifications might not benefit as much or could experience compatibility issues. Always verify compatibility with your exact engine model and year.

8. **Cost of Additional Components**

While the impeller kit itself is affordable, you may need to purchase additional parts (e.g., a new propeller, gaskets, or seals) to fully optimize performance, adding to the overall cost.

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### **Conclusion**

The **Mercury 803373 Impeller Kit** is a worthwhile upgrade for boaters looking to enhance throttle response, cooling efficiency, and overall engine performance in their Mercury outboards. Its benefits are most pronounced in scenarios where the stock impeller struggles, such as in warm water, under heavy loads, or when paired with other performance modifications. The installation is straightforward, and the kit is durable, making it a practical choice for both DIY enthusiasts and professionals.

However, the gains are not revolutionary for stock setups, and it may require complementary upgrades (like a propeller change) to fully realize its potential. The kit is best suited for those who prioritize reliability, reduced cavitation, and smoother operation rather than extreme performance gains. If your engine is already heavily modified or experiencing issues unrelated to impeller performance, this upgrade alone may not be sufficient.

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### **Recommendation**

- You notice poor throttle response, cavitation, or overheating in your Mercury outboard.

- You plan to pair it with other performance upgrades (e.g., a larger propeller or exhaust system).

- You want a cost-effective way to improve engine efficiency and longevity.

- Your engine is within the kit s specified compatibility range.

- Your engine is already heavily modified, and you re unsure how the impeller will interact with other changes.

- You re experiencing issues unrelated to impeller performance (e.g., fuel system problems, electrical faults).

- You re operating in very cold water and are concerned about overcooling (though this is rarely a significant issue).

- You re on a tight budget and cannot afford complementary upgrades (e.g., a new propeller).

**Final Verdict:** For most Mercury outboard owners seeking a simple yet effective performance boost, the **803373 Impeller Kit is a solid choice**. It s a low-risk upgrade with measurable benefits, especially for those who frequently push their engines to their limits. Pair it with a properly sized propeller and regular maintenance for the best results.

Details:

This kit includes an impeller specifically designed for Mercury outboard engines, ensuring optimal performance and efficiency. The Mercury OEM Impeller Kit 803373 is a genuine replacement part made by in the USA. While this product does not come with a warranty, it is reliable and durable component that can help extend the lifespan of your boats engine.

part #: 803373 prices

• $12.99-$29.99

specifications ouboaen:

• for makes: Mercury
• mpn: 803373
• part type: Impeller
• country of origin: United States

seller ouboaen:

• city: Perrinton, Michigan
• rating: 99.8%
• # reviews: 4621

general ouboaen:

• Boat Parts > Outboard Engines Components > Other
• condition: New

offer ouboaen:

• sold: 0
• started: April 16, 2026
• quantity: 1
• availability: In Stock
• best offers: True
• options: Ship-to-home

shipping ouboaen:

• service: Standard
• type: Fixed
• class: Standard
• transit: 4-8 Days
• cost: $6.00

returns ouboaen:

• policy: Returns Accepted
• paid by: Seller
• time: 30 Days

payments ouboaen:

• wallet: Apple-pay
• credit card: Mastercard
• other

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