BUICK 407.GM4121 Gx Automatic Transmission Torque Converter Encoregx

( Model: ENCOREGX ), ( Part Type: Torque Transmission Converter ), ( Conditions Options: 4, 1.3, At, Awd ), ( Genuine Oem: Yes ), ( Ipn: 407.gm4121 ), ( Year: 2021 ), ( Manufacturer Warranty: 60 Day ), ( Partout Id: A-121725763 )

Review BUICK Gx Automatic Transmission Torque Converter fits ENCORE 2020–2023

The **Buick 407 V8 Engine (GM4121) with Encore GX Automatic Transmission and Torque Converter** represents a refined fusion of power, precision, and modern automotive engineering, designed to deliver an exhilarating yet smooth driving experience for discerning enthusiasts and performance-oriented drivers. This high-performance powerplant, a direct evolution of Buick s legendary V8 lineup, embodies cutting-edge technology while maintaining the brand s signature blend of luxury and mechanical prowess. The **407 cubic-inch (7.0L) naturally aspirated V8** is a masterpiece of engineering, featuring a compact, lightweight design that maximizes torque delivery and efficiency without sacrificing the raw, throaty growl that V8 enthusiasts crave. With a **compression ratio of 10.5:1**, this engine achieves an impressive **400 horsepower** and **430 lb-ft of torque**, figures that are both substantial and well-balanced, ensuring a responsive yet controlled drive from idle to redline. The **direct-injection fuel system** enhances efficiency and performance, while the **high-flow intake and exhaust manifolds** optimize airflow for peak power output, making it a standout choice for those seeking a balance between daily drivability and spirited acceleration.

At the heart of this engine s seamless integration lies the **Encore GX 8-speed automatic transmission**, a sophisticated and highly refined powertrain solution engineered by General Motors to deliver effortless shifts, improved fuel economy, and enhanced durability. This transmission is a testament to modern transmission technology, featuring **dual-clutch and wet-summed torque converter technology** that ensures rapid, near-instantaneous gear changes while minimizing wear and tear. The **torque converter**, specifically designed for the 407 V8, is a **GM4121 Encore GX unit**, optimized for the engine s torque output, providing a smooth and progressive lock-up for improved efficiency and a more engaging driving experience. The transmission s **adaptive shift logic** learns driver preferences over time, anticipating gear changes to optimize performance, whether cruising on the highway or navigating tight city streets. Additionally, the **Encore GX s advanced cooling system** and **robust construction** contribute to longevity, making it a reliable companion for both daily commuters and weekend track adventurers.

The **407 V8 s architecture** is a study in modern engineering, incorporating **forged crankshaft, high-strength connecting rods, and a robust cylinder block** to withstand the demands of high-performance driving. The **variable valve timing (VVT)** system on both the intake and exhaust camshafts dynamically adjusts valve lift and timing to maximize efficiency and power across the entire RPM range, ensuring that the engine operates at its peak regardless of driving conditions. The **high-flow cylinder heads**, featuring **four valves per cylinder**, promote superior combustion and airflow, while the **reinforced oil pump and cooling system** guarantee consistent lubrication and thermal management, even under heavy loads. This attention to detail extends to the **exhaust system**, which is designed to channel exhaust gases efficiently while contributing to the engine s signature deep, resonant growl a hallmark of Buick s V8 heritage.

For those seeking a complete performance package, the **407 V8 with Encore GX transmission and torque converter** is a compelling choice, offering a harmonious blend of power, refinement, and adaptability. Whether integrated into a **Buick Envision, Buick Enclave, or other GM full-size SUVs**, this powertrain delivers a driving experience that is both thrilling and comfortable. The **torque converter s smooth engagement** and the transmission s **precise shift quality** ensure that power is delivered with minimal hesitation, while the engine s **wide power band** provides effortless acceleration without sacrificing fuel efficiency. This combination makes it an ideal candidate for those who appreciate the best of both worlds: the raw excitement of a V8 and the practicality of modern automatic transmission technology. With its **durable construction, advanced features, and Buick s signature attention to detail**, this powertrain is not just a component it s a statement of automotive excellence.

### **Pros and Cons of Buying a 2020 2023 Buick Enclave with the GM 4L65-E (4121) Automatic Transmission and Torque Converter**

The **2020 2023 Buick Enclave** is a midsize luxury SUV powered by a **3.6L V6 engine** paired with a **GM 4L65-E (also known as the 4121) 6-speed automatic transmission** and a **torque converter**. This powertrain combination is reliable but has some trade-offs. Below is a detailed breakdown of its advantages and disadvantages.

---

### **Pros**

1. **Proven Reliability of the 3.6L V6 Engine**

- The **3.6L V6 (LFX engine)** is a well-established GM powertrain, used in multiple models (Enclave, Regal, Traverse) since the early 2010s. It is known for durability when maintained properly.

- Produces **288 300 hp and 268 lb-ft of torque**, providing strong performance for a midsize SUV.

- Fewer issues compared to some newer turbocharged engines, making it a safer long-term choice.

2. **Strong Transmission (4L65-E / 4121)**

- The **4L65-E is a robust 6-speed automatic** with a **torque converter**, designed for heavy-duty applications (originally used in trucks and larger SUVs).

- Handles the V6 s power well, with smooth shifts when properly serviced.

- More durable than some modern "easy-shift" transmissions, meaning fewer electronic failures.

3. **Good Fuel Economy for a V6 SUV**

- Expect **18 20 MPG city / 25 27 MPG highway** (varies slightly by year and trim).

- Better than many turbocharged V6s or diesel alternatives in this class.

4. **Luxury & Comfort Features**

- The Enclave offers a **spacious, upscale interior** with premium materials (depending on trim).

- Standard features include **heated/ventilated seats, Bose audio, and advanced safety tech** (like forward collision warning and blind-spot monitoring).

- Comfortable ride quality, suitable for highway driving.

5. **Lower Maintenance Costs Compared to Some Competitors**

- The V6 and transmission are **less expensive to repair** than turbocharged engines or complex hybrid systems.

- No forced induction means fewer issues with carbon buildup or turbo failures.

6. **Good Resale Value**

- Buicks hold their value reasonably well, especially compared to some luxury brands.

- The Enclave remains a **practical luxury SUV**, appealing to buyers who want comfort without extreme luxury pricing.

7. **Torque Converter Advantages**

- The **torque converter** provides **better towing capacity** (up to **3,500 lbs** when properly equipped) compared to some CVT-based SUVs.

- More torque delivery at low RPMs, improving acceleration in stop-and-go traffic.

---

### **Cons**

1. **Transmission & Torque Converter Weaknesses**

- The **4L65-E is notorious for torque converter failures**, especially in high-mileage examples.

- **Common issues:** Slipping, overheating, or complete converter failure (often requiring a **$1,500 $2,500 replacement**).

- **Symptoms:** Rough shifting, delayed engagement, or a "whining" noise under load.

- **Fluid changes are critical** many owners neglect this, leading to premature failure.

- **Band wear** can cause **jerky shifts or failure to engage gears** over time.

2. **Poor Fuel Economy for a V6**

- While decent for a non-turbo V6, it **lags behind turbocharged or hybrid competitors** (e.g., Toyota Highlander Hybrid gets 30 MPG combined).

- If fuel efficiency is a priority, a **turbocharged V6 (like in the 2020 Enclave with the LTG engine)** or a hybrid would be better.

3. **Outdated Tech Compared to Competitors**

- The **infotainment system (Uconnect 4 or 5)** is **laggy and less intuitive** than rivals like Ford s SYNC 4 or GM s newer Uconnect 5 (which still has issues).

- **No wireless Apple CarPlay/Android Auto** until 2023 (some trims).

- **Regenerative braking is weak**, meaning the hybrid Enclave still gets **similar MPG** in real-world driving.

4. **Rust & Body Quality Concerns**

- GM has had **rust issues** in some Enclave models, particularly in **roof rails, wheel wells, and undercarriage**.

- **Check for rust** before buying, especially in snowy/salty regions.

- Some owners report **excessive road noise** due to thin body panels.

5. **Engine & Transmission Noise**

- The **3.6L V6 can be noisy** at highway speeds (some describe it as "loud").

- The **transmission can make clunking noises** if fluid is old or bands are worn.

- **Torque converter whine** is a common complaint in high-mileage examples.

6. **Limited Towing & Off-Road Capability**

- While it can tow **up to 3,500 lbs**, it lacks **proper towing packages** (unlike some GMC/Yukon models).

- **No true off-road mode** stuck with basic traction control.

- **Suspension is firm but not aggressive**, making it less capable than a Jeep or Ford Edge ST.

7. **Resale Depreciation**

- Buicks **depreciate faster than luxury brands** (Lexus, Acura, Cadillac).

- The **Enclave is not as desirable** as a Toyota Highlander or Honda Pilot, meaning lower long-term value.

8. **Maintenance Costs Can Add Up**

- While parts are affordable, **transmission and converter replacements are expensive**.

- **Timing chain wear** (a known issue in some GM V6s) can lead to **engine damage if ignored**.

- **Oil leaks** from valve cover gaskets or oil filter housing gaskets are common.

---

### **Key Considerations Before Buying**

1. **Transmission & Converter Health**

- **Always check service records** was the **transmission fluid changed at 60K 90K miles**? (It should be **every 60K miles** for this transmission.)

- **Listen for whining or slipping** these are **red flags**.

- **Get a pre-purchase inspection** focusing on the **torque converter and transmission mounts**.

2. **Engine Condition**

- **Listen for ticking or knocking** (could indicate timing chain wear).

- **Check for oil leaks** (valve cover, oil filter housing).

- **Test drive at highway speeds** excessive vibration or noise may indicate **engine or suspension issues**.

3. **Rust Inspection**

- **Check undercarriage, wheel wells, and rocker panels** for rust.

- **Look for paint delamination** (bubbling) on the roof and doors.

4. **Alternatives to Consider**

- **Toyota Highlander Hybrid** (better MPG, more reliable long-term).

- **Honda Pilot** (more refined, better resale value).

- **Ford Edge ST** (if you want more power and tech).

- **Chevy Tahoe/GMC Yukon** (if towing is a priority).

---

### **Final Recommendation**

You **prioritize reliability over cutting-edge tech** and can **budget for potential transmission/converter repairs**.

You **need a spacious, comfortable SUV** for daily driving and light towing.

You **find a well-maintained example** (proper fluid changes, no rust, no transmission symptoms).

You **don t mind a slightly older infotainment system** and prefer a **traditional automatic transmission** over a CVT.

You **live in a mild climate** (less risk of rust-related issues).

You **can t afford a $1,500 transmission/converter repair** if needed.

You **need excellent fuel economy** a hybrid or turbocharged model would be better.

You **find excessive rust or neglect in the vehicle s history**.

You **want the latest tech** the Enclave s infotainment is outdated compared to competitors.

You **plan to tow heavily** consider a **GMC Yukon or Ford Expedition** for better towing packages.

- **Buy from a reputable dealer or private seller with full service records.**

- **Get a pre-purchase inspection** (especially for transmission and rust).

- **Budget for potential transmission fluid changes** (every 60K miles).

- **Consider a 2022 2023 model** (they have **minor updates**, including

Details:

It is stored in doors and ready to be shipped. Donor Vehicle - 2021 ENCOREGX. Stock Number - 2601. 4 ,1.3,AT,AWD.

Torque converter.

specifications torquconv:

• for models: Encore
• for makes: Buick
• for years: 2020-2023
• model: Encoregx
• part type: Torque Transmission Converter
• conditions options: 4, 1.3, At, Awd
• genuine oem: Yes
• ipn: 407.gm4121
• year: 2021
• manufacturer warranty: 60 Day
• partout id: A-121725763

payments torquconv:

• wallet: Paypal
• credit card: Diners-club
• other

returns torquconv:

• paid by: Buyer
• time: 60 Days
• policy: Returns Accepted

general torquconv:

• Car Truck Parts Accessories > Transmission Drivetrain > Torque Converters
• condition: Used

seller torquconv:

• city: Sauk Centre, Minnesota
• rating: 99.7%
• # reviews: 28781

offer torquconv:

• options: Ship-to-home
• started: April 7, 2026
• best offers: True
• availability: In Stock
• quantity: 1
• sold: 0

shipping torquconv:

• cost: $0.00
• service: UPS Ground
• transit: 2-4 Days
• type: Fixed
• carrier: UPS
• class: Standard

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