PORSCHE 99610400303 Left Cylinder Head 306-59495L 3.4 1/3

( Manufacturer Part Number: 99610400303 ), ( Ipn: 306-59495l ), ( Storage Location: X3c04 ), ( Note: Cylinder 1-3 ), ( Engine: 3.4 ), ( Oe/oem Part Number: 996-104-003-03; 996.104.003.03; 996 104 003 03 ), ( Placement On Vehicle: Left Driver ), ( Country Of Origin: Germany ), ( Type: Cylinder Head ), ( Brand Type: Genuine Oem ), ( Fitment Notes: Specializedgerman 2025 )

Review PORSCHE 3.4 Left Cylinder 1-3 Head Oem Used fits 911 1999–2001

The **Porsche 996 911 (99610400303) from the 1999 2001 model years** represents a rare and highly sought-after variant of the iconic 911, distinguished by its **3.4-liter flat-six engine** paired with a unique **left-side cylinder head configuration (cylinders 1-3)** a modification that sets it apart from the standard right-side head (cylinders 4-6) found in most 996 models. This engine variant, often referred to as the **"3.4L left-head"** or **"3.4L 996,"** was produced in limited quantities, primarily for homologation purposes and as a performance-oriented option for select customers. Under the hood, this engine features a **cast-iron block** with a **dry-sump lubrication system**, a **double overhead camshaft (DOHC)** design, and **four valves per cylinder**, delivering a smooth yet aggressive power delivery. With a **compression ratio of 10.5:1**, it produces approximately **300 horsepower** (depending on tuning and modifications) and **248 lb-ft of torque**, making it one of the most powerful naturally aspirated 911 engines of its era. The **left-side cylinder head** modification was likely implemented to balance weight distribution or address specific tuning requirements, though it also introduces a unique aesthetic and mechanical distinction.

Mechanically, the **3.4L engine** shares many components with the more common **3.6L 996 models**, including the same **9A1/9A2 transmission options** (manual or PDK-equivalent Tiptronic automatic) and **multi-link rear suspension**, but its larger displacement and revised internals such as a **stiffer crankshaft** and **reinforced connecting rods** allow for greater reliability when properly maintained. The **left-head configuration** also influences the engine s breathing characteristics, with the intake and exhaust manifolds routed differently, which can affect tuning potential and sound signature. This variant was often paired with the **996 s signature "9A2" chassis**, featuring a **monocoque construction**, **torsion beam rear axle**, and **adjustable dampers** for precise handling. The **3.4L left-head 911** was typically offered in **Cabriolet or Targa** body styles, though coupes were rare, adding to its exclusivity.

Externally, the **1999 2001 996 911** retains the **996 s signature design language**, including the **sharp, angular headlights**, **swept-back fenders**, and **sporty rear diffuser**, though it may feature subtle differences in badging or trim depending on the market. The **left-head engine bay** often reveals a slightly different valve cover design, with the **cylinder numbering** (1-3) clearly visible when the cover is removed, serving as a quick identifier for enthusiasts. Inside, the cabin remains true to Porsche s **minimalist, driver-focused philosophy**, with **recaro seats**, **wood or Alcantara trim options**, and **digital dash displays** (depending on the model year). The **3.4L variant** was often equipped with **higher-performance upgrades**, such as **stiffer suspension components**, **larger brake rotors**, and **adaptive dampers**, making it a standout even among 996 models.

One of the most compelling aspects of the **3.4L left-head 911** is its **tuning potential**. Due to its **cast-iron block** and **dry-sump system**, it can handle significant modifications, including **forged internals, high-flow heads, and aggressive camshafts**, allowing it to surpass **400 horsepower** with proper engineering. The **left-head configuration** also makes it a favorite among **homemade engine builders**, as the unique cylinder arrangement allows for creative modifications. However, it s worth noting that **finding genuine OEM parts** for this variant can be challenging, as production numbers were low, and many components were shared with other 996 models.

Today, the **1999 2001 3.4L left-head 911** is a **highly collectible and performance-oriented** Porsche, prized by both **restoration enthusiasts** and **track-focused drivers**. Its **rare engine variant**, **strong mechanical foundation**, and **tuning potential** make it a **standout in the 996 lineup**, offering a blend of **classic 911 charm** and **modern performance capabilities**. Whether used for **daily driving, track days, or as a project car**, this **left-head 3.4L 996** remains a **unique and powerful** representation of Porsche s engineering excellence from the late '90s.

### **Pros and Cons of Buying a 1999-2001 Porsche 996 (911, 3.4L, Left Cylinder 1-3 Head)**

#### **Pros**

1. **Classic 996 Design with Modern Appeal**

The 996 generation marked a shift from the boxy 993 to a more angular, aerodynamic design that remains recognizable and desirable. While some critics dislike its styling, it has a cult following, and well-maintained examples hold value.

2. **Improved Handling and Chassis**

The 996 introduced a more refined suspension setup compared to the 993, with better road manners and a more composed driving experience. The wider track and improved weight distribution make it more stable at high speeds.

3. **Reliable 3.4L Flat-Six Engine**

The M96 engine (3.4L, 325 hp in base models) is a robust powerplant when properly maintained. It s less prone to catastrophic failure compared to earlier 911 engines if serviced regularly. The left cylinder head (1-3) issue is a known concern, but if addressed early, it won t cause major problems.

4. **Good Performance for the Era**

The 3.4L engine provides strong acceleration (0-60 mph in 5.5 seconds in base models) and a linear power delivery. The manual transmission is engaging, and the PDK (in later models) offers a futuristic touch.

5. **Aftermarket Support**

The 996 has a strong aftermarket presence, with parts, upgrades, and tuning solutions widely available. Performance chips, exhaust systems, and suspension kits are common, allowing owners to tailor the car to their preferences.

6. **Potential for Restoration or Modification**

If you enjoy working on cars, the 996 offers a good project opportunity. Many owners strip, restore, or modify these cars, which can be rewarding. The base price is relatively affordable compared to later 997 models.

7. **Niche Market Appeal**

While not as sought-after as the 997 or 991, the 996 has a dedicated fanbase. Well-documented, low-mileage examples can be a good investment if you plan to hold onto it long-term.

---

#### **Cons**

1. **Left Cylinder Head (1-3) Issue**

The most critical problem with this engine variant is the **left cylinder head (1-3) cracking or warping**, often due to overheating or poor maintenance. Symptoms include:

- White smoke from the exhaust

- Coolant mixing with oil

- Loss of compression in cylinders 1-3

- Overheating

This is a **major concern** if the head is cracked, it requires a full rebuild or replacement, which can be expensive ( 3,000 6,000 depending on labor and parts).

2. **Electrical and Software Quirks**

- Faulty sensors (e.g., crankshaft, camshaft, or MAF sensors)

- Check engine lights (CEL) for minor issues like oxygen sensor failures

- Infotainment system (if equipped) can be glitchy or require updates

- Poor-quality wiring in some models (especially early 1999 2000)

3. **Rust and Corrosion**

Many 996s, especially in colder climates, suffer from rust in the wheel arches, subframe, and rear quarter panels. A thorough inspection is **essential** rust can lead to structural weakness and costly repairs.

4. **Transmission Issues (Manual and PDK)**

- **Manual transmissions** can develop rough shifting or synchro wear if not maintained.

- **PDK (2001 models)** is advanced but complex fluid changes are critical, and failures can be expensive.

- Early manuals (especially in 1999 2000) may have stiff or noisy clutches.

5. **Interior Quality and Comfort**

The 996 s interior is **basic by modern standards** hard plastics, poor sound insulation, and a stiff ride make long drives less enjoyable. Heating and cooling systems can be inefficient.

6. **Fuel Economy and Practicality**

The 3.4L engine is thirsty ( 12 14 MPG combined), and the car is narrow, making it less practical for daily use. The trunk is small, and rear visibility is poor.

7. **Depreciation and Market Value**

While not a "bad" car, the 996 does not hold value as well as later 911 models (997, 991). If you plan to sell later, expect lower resale value compared to a 997 or 991.

8. **Maintenance Costs**

- Timing belt replacement ( 1,000 1,500 every 60,000 80,000 miles)

- Spark plugs, coils, and sensors need attention

- Brake systems (especially rear calipers) can wear out quickly

- Suspension components (shocks, bushings) may need replacement

---

### **Key Considerations Before Buying**

1. **Left Cylinder Head Check**

- **Must verify the head is intact** request a **compression test** or **leak-down test** before purchasing.

- If the head is cracked, **budget for a rebuild** ( 3,000 6,000 ).

- Some owners opt for a **right cylinder head swap** (less common but possible).

2. **Service History**

- Look for **regular oil changes, timing belt replacements, and head gasket checks**.

- A car with **no service records** is a red flag.

3. **Rust Inspection**

- Check **wheel arches, subframe, rear quarter panels, and rocker panels** for rust.

- A **full undercarriage inspection** is ideal.

4. **Electrical System**

- Test all **sensors, lights, and electronics** common issues include faulty crankshaft sensors or CELs.

- If the car has **infotainment**, ensure it s functional.

5. **Transmission Condition**

- For manuals: Check for **smooth shifting, no grinding, and clutch condition**.

- For PDK: Verify **fluid levels and no warning lights**.

6. **Test Drive**

- Listen for **unusual noises** (knocking, rattling, or whining).

- Check for **vibration, poor steering response, or handling issues**.

- Test **brakes, suspension, and throttle response**.

---

### **Conclusion and Recommendation**

#### **Who Should Buy This Car?**

**You re a Porsche enthusiast who enjoys working on projects** and doesn t mind spending time restoring/modifying.

**You ve budgeted for potential major repairs** (especially the left cylinder head).

**You prefer a classic 996 design** over the 997 s more modern look.

**You plan to keep it long-term** (as a collector or project car).

**You find the 3.4L engine reliable enough** after proper maintenance.

#### **Who Should Avoid This Car?**

**You want a low-maintenance, daily driver** this is not a practical car.

**You can t afford unexpected repairs** (especially the left cylinder head).

**You dislike the 996 s styling** and prefer the 997 or 991.

**You re buying without a thorough inspection** always get a **pre-purchase inspection (PPI)** from a Porsche specialist.

#### **Final Recommendation**

If you **find a well-documented, low-mileage 996 3.4L with a confirmed intact left cylinder head**, it can be a **great project car or a fun daily driver** for an enthusiast. However, **expect to spend money on maintenance** this is not a "set-and-forget" Porsche.

**Best Alternative?**

- If you want a **more reliable 996**, consider a **3.6L (996.2, 2000 2004)** it s less prone to cylinder head issues.

- If you want a **more modern 911**, a **used 997 (2005 2012) or 991 (2012 2019)** may be a better long-term investment.

- If you re on a **tight budget**, a **993 (1995 1998) in good condition** could be a better value, despite its quirks.

Buy **only if you re prepared for potential repairs and enjoy the challenge**. Otherwise, consider a newer 911 model for better reliability and resale value. Always **inspect thoroughly** or have a mechanic do so before purchasing.

Details:

Most or all European electronic devices Stereo, ECU, Modules, etc. Need to be programmed. These items are not Plug and Play. All new fluids, gaskets, filters and seals must be used upon installation of all parts. These items need to be coded the vehicle they are being installed into.

Putting you back on the road is only half story. All maintenance procedures must be properly followed at intervals least as frequent recommended by the vehicle manufacturer. And with over ten thousand vehicles dismantled for parts, that goal is a reality. Manufacturer Part Number.

Storage Location: X3C04. Radio / Stereo. Doing the right thing for your vehicle, wallet, and environment. Chassis: 996.

Country/Region of Manufacture: Germany. From engines to emblems. We really do have it all. Giving you access to virtually every part on car.

Item Specifics. Electrical parts are not returnable if installed. Condition: Used. In addition, all applicable coolers, lines and filters must be flushed clean before installation to prevent contamination premature failure.

Please save all packaging materials and damaged goods before filing a claim. 1999 2001 Porsche 911 996 3.4 Left Cylinder 1-3 Head OEM Used: Brand. Most radios require a security code or password to unlock the unit for use. BMW Parts Porsche Audi Volkswagen Other Makes.

They require specific tools or information to program. Make: Porsche.

part #: 99610400303 prices

• $400.00-$2100.00

specifications cylinderheapar:

• for models: 911
• for makes: Porsche
• for years: 1999-2001
• mpn: 99610400303
• ipn: 306-59495l
• storage location: X3c04
• note: Cylinder 1-3
• engine: 3.4
• oe/oem part number: 996-104-003-03; 996.104.003.03; 996 104 003 03
• placement on vehicle: Left Driver
• country of origin: Germany
• type: Cylinder Head
• brand type: Genuine Oem
• fitment notes: Specializedgerman 2025

returns cylinderheapar:

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

general cylinderheapar:

• Car Truck Parts Accessories > Engines Engine Parts > Cylinder Heads
• condition: Used

offer cylinderheapar:

• options: Ship-to-home
• best offers: True
• quantity: 1
• started: February 9, 2026
• sold: 0
• availability: In Stock

shipping cylinderheapar:

• class: Standard
• type: Fixed
• carrier: USPS, UPS
• cost: $0.00
• transit: 3-10 Days
• service: USPS Ground Advantage, UPS Ground

payments cylinderheapar:

• money order
• check
• cash
• credit card: Mastercard
• other
• wallet: Apple-pay

seller cylinderheapar:

• rating: 99.9%
• city: Rancho Cordova, California
• # reviews: 74853

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