MARINER 38051T Outboard Plate Seal 37641 90HP 6-CYL T4

( Brand: Mariner ), ( Manufacturer Part Number: 38051T ), ( Part Type: Seal Plate ), ( Country Of Origin: United States )

Review MARINER 90hp 6-cyl Outboard Plate And Seal T4 fits 1984

The **Mariner 38051T 37641 1984 90 Horsepower 6-Cylinder Outboard Motor** is a classic example of Mercury Marine s legendary craftsmanship from the early 1980s, designed to deliver both power and reliability for serious anglers, boaters, and weekend adventurers. This model, part of Mercury s iconic 90 HP series, features a robust **6-cylinder, two-stroke engine** with a displacement of **37641 cubic centimeters**, producing a smooth yet punchy **90 horsepower** ideal for mid-sized boats ranging from 20 to 26 feet. The motor is built on a **T4 (Twin-4) chassis**, a hallmark of Mercury s engineering at the time, which balances performance with durability, making it a sought-after choice for those seeking a balance between power and efficiency.

One of the standout features of this outboard is its **direct-drive, single-reduction gearing**, which ensures strong acceleration and consistent torque without the complexity of multi-reduction systems. The **cast-aluminum lower unit** is designed for longevity, with a **sealed propeller shaft** and a **high-strength bronze propeller shaft nut** to prevent corrosion and ensure smooth operation. The **Mariner 38051T** also incorporates a **twin-screw cooling system**, which helps maintain optimal engine temperatures even under heavy loads, reducing the risk of overheating during extended runs. The **fuel-injected carburetion** (for the 1984 model year) enhances throttle response and fuel efficiency, providing a more refined power delivery compared to earlier carbureted designs.

For those who appreciate both performance and practicality, this outboard includes a **direct-drive, single-reduction gearing** system, which simplifies maintenance while delivering strong acceleration. The **cast-aluminum lower unit** is built to last, featuring a **sealed propeller shaft** and a **high-strength bronze propeller shaft nut** to resist corrosion and ensure smooth operation. The **Mariner 38051T** also incorporates a **twin-screw cooling system**, which helps regulate engine temperature even under heavy loads, reducing the risk of overheating during long runs. The **fuel-injected carburetion** (a refinement from the 1984 model year) improves throttle response and fuel economy, offering a more polished power delivery than earlier carbureted versions.

The **plate seal** (T4 designation) indicates a **twin-engine configuration**, where two separate 45 HP engines are paired in a single housing, sharing a common gearcase and steering mechanism. This setup was popular in the early 1980s for its reliability and ease of maintenance, as individual cylinders could be serviced without overhauling the entire motor. The **direct-drive system** eliminates the need for a complex transmission, reducing wear and tear while maintaining strong performance. The **cast-aluminum cowling** is both lightweight and durable, designed to withstand the rigors of saltwater environments, though owners should note that the **fiberglass-reinforced cowling** of later models offers even greater corrosion resistance.

Under the hood, the **6-cylinder, two-stroke engine** runs on a **single overhead camshaft (SOHC) design**, which, while not as advanced as modern multi-valve systems, delivers a robust and dependable power output. The **wet-sump lubrication system** ensures consistent oil flow, reducing friction and extending engine life, while the **pressure-lubricated main bearings** provide smooth operation under load. The **direct-drive propeller shaft** is housed in a **sealed lower unit**, minimizing water ingress and corrosion a critical feature for saltwater applications. The **Mariner 38051T** also includes a **manual choke system** and a **pull-start mechanism**, making it easy to start even after prolonged periods of inactivity.

For boaters who value both performance and simplicity, this outboard is a fantastic choice, offering **90 horsepower of reliable power** with minimal maintenance requirements. The **T4 twin-engine configuration** allows for easy servicing of individual cylinders, while the **direct-drive system** ensures strong acceleration without the complexity of modern multi-reduction gearboxes. The **cast-aluminum construction** is built to endure, though owners should be prepared for occasional **seal and gasket replacements** as the motor ages. With proper care, this **1984 Mercury Marine 90 HP 6-cylinder outboard** remains a fantastic option for those seeking a **proven, high-performance engine** that can handle everything from fishing trips to weekend cruises.

Whether used on a **20-foot center console, a 24-foot deck boat, or a mid-sized cabin cruiser**, this motor delivers **smooth, responsive power** with the classic Mercury reliability that has made it a favorite among boating enthusiasts. While modern outboards offer advanced electronics and fuel injection systems, the **Mariner 38051T** stands out for its **simplicity, durability, and the raw power of its 6-cylinder engine** making it a prized addition to any collection of vintage marine engines. For those who appreciate the **craftsmanship of an earlier era**, this outboard is a testament to Mercury s legacy of building motors that **last, perform, and inspire**.

### **Pros and Cons of Buying a 1984 Mercury 37641 90HP 6-Cylinder Outboard (Mariner 38051T, Plate Seal, T4)**

1. **Classic Reliability** Mercury 6-cylinder outboards from the early 1980s are known for durability, especially the 90HP model, which was a workhorse for its time. Many still run strong with proper maintenance.

2. **Lower Purchase Price** Compared to newer outboards, this model is significantly cheaper, making it an attractive option for budget-conscious buyers.

3. **Good for Small to Medium Boats** The 90HP engine is well-suited for boats in the 18 22-foot range, providing adequate power for cruising, fishing, or light planing.

4. **Parts Availability** While not as common as newer models, Mercury 6-cylinder parts (especially for the 90HP) are still available through marine dealers, salvage yards, and online marketplaces.

5. **Potential for Restoration** If the engine is in rough shape, a skilled mechanic may be able to restore it to good working condition, increasing its lifespan.

6. **Lower Fuel Consumption** Compared to modern high-performance outboards, this engine is more fuel-efficient, which can be beneficial for long trips.

7. **Mariner Series (38051T)** The Mariner trim suggests it was designed for fishing or cruising, meaning it may have features like a more robust lower unit or better cooling.

8. **Plate Seal (T4) Advantage** The plate seal (T4) indicates a more robust lower unit construction, which can be more durable than older gasket-style seals.

1. **Age and Wear** At nearly 40 years old, this engine will likely have significant wear, including piston rings, bearings, and internal seals. Expect high maintenance costs.

2. **Fuel System Issues** Older carbureted engines (this model is likely carbureted) are prone to clogged jets, worn diaphragms, and fuel pump failures. Modern fuel injection systems are far more reliable.

3. **Electrical Problems** Wiring, starter motors, and ignition systems from this era can be finicky, requiring frequent adjustments or replacements.

4. **Emissions and Modern Regulations** This engine does not meet modern emissions standards, meaning it cannot be used on many public waters without modifications (which may not be worth the effort).

5. **Limited Performance** Compared to modern outboards, this engine lacks power, efficiency, and modern features like electronic diagnostics, trim systems, and fuel injection.

6. **Rust and Corrosion** If the engine has been stored improperly, rust in the lower unit, exhaust, or fuel system could be a major issue.

7. **Difficulty Finding Skilled Mechanics** While Mercury outboards are classic, fewer mechanics specialize in older models, making repairs more challenging and expensive.

8. **Resale Value** Even if restored, this engine will not hold value well compared to newer or well-maintained older outboards.

9. **Potential for Hidden Damage** Without a thorough inspection (including a test run), there could be internal damage (bent rods, cracked pistons, or worn crankshafts) that would require expensive repairs.

10. **Environmental Concerns** Older two-stroke outboards (if this is one) are known for poor fuel efficiency and higher emissions, which may not align with modern environmental standards.

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### **Conclusion and Recommendation**

This **1984 Mercury 37641 90HP 6-cylinder outboard** is a **project engine** rather than a turnkey solution. It could be a **great find for someone with mechanical skills, patience, and a low budget**, particularly if:

- You plan to **restore it yourself** or have a trusted mechanic do so.

- You need a **budget outboard for a small boat** where performance isn t critical.

- You re okay with **higher maintenance costs** and potential downtime.

- You don t mind **older technology** and are not concerned about emissions compliance.

However, if you re looking for a **reliable, low-maintenance engine** that will last for years with minimal hassle, this is **not the best choice**. Modern **4-stroke outboards** (even older but well-maintained ones) or **rebuilt classic outboards** would be far more practical.

- You have **mechanical experience** or access to a **trusted mechanic** who can assess and restore it properly.

- You re **prepared for high maintenance costs** (expect to spend **$1,500 $3,000 ** on a full rebuild if needed).

- You **don t need high performance** and are okay with an older, less efficient engine.

- You **plan to use it sparingly** (e.g., occasional fishing trips rather than frequent boating).

- You want a **plug-and-play engine** with minimal upkeep.

- You need **modern reliability, fuel efficiency, or emissions compliance**.

- You re not comfortable with **older mechanical systems** (carburetors, manual adjustments, etc.).

- You re looking for **long-term value** this engine will not appreciate in worth.

- A **rebuilt 1990s early 2000s Mercury 90HP 4-stroke** (more reliable, better fuel economy).

- A **used 4-stroke outboard** (e.g., Yamaha, Suzuki, or Evinrude) from the **2000s onward** for better performance and lower long-term costs.

- A **smaller, modern 4-stroke** (e.g., 60 80HP) if you don t need the full 90HP.

If you proceed with this purchase, **inspect it thoroughly** (or have a professional do so) before buying, and **budget for a full rebuild** if it s in poor condition. Otherwise, you may end up with a **money pit** rather than a reliable engine.

Details:

Recombine shipping on multiple items. Parts off of a 1984 Mariner 90hp inline 6-cylinder Tower Power, 2-stroke, freshwater outboard motor, model 7090624, serial 6436752, long shaft for 20 transoms, motor had low compression. Just because the part looks right does not mean that Otis. Pleasured entire listing before buying or purchasing item.

Mariner Gray. They will however be in functioning and usable condition. We operate in Central Standard Time. Keeping mind that if the listing is for a used part, it used part, so there may be some minor cosmetic damage scratches/scuffs.

part #: 38051t price

• $14.99

specifications ouboaen:

• for years: 1984
• brand: Mariner
• mpn: 38051t
• part type: Seal Plate
• country of origin: United States

seller ouboaen:

• # reviews: 6415
• rating: 99.9%
• city: Melrose, Minnesota

returns ouboaen:

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

general ouboaen:

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

payments ouboaen:

• other
• wallet: Paypal
• credit card: Discover

offer ouboaen:

• availability: In Stock
• started: June 1, 2026
• sold: 0
• quantity: 1
• options: Ship-to-home

shipping ouboaen:

• transit: 3-7 Days
• cost: $0.00
• class: Standard
• type: Fixed
• service: Standard

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