MERCEDES Front Crankshaft Seal Benz A0039970347

( Manufacturer Part Number: 0039970347 ), ( Part Type: Seal Crankshaft ), ( Items Included: Seal ), ( Customs And Taxes: No Customs Fees For Usa Customers ), ( Country Of Origin: Germany ), ( Reference Oe/oem Number: A0039970347 )

Review MERCEDES benz New S class Front Crankshaft Seal fits W126

The **Mercedes-Benz 0039970347 S-Class (W126) Front Crankshaft Seal (A0039970347)** is a precision-engineered component designed to maintain the integrity of the engine s front oil seal interface, ensuring long-term reliability and optimal performance in one of the most iconic luxury sedans of the late 20th century. Manufactured to Mercedes-Benz s exacting standards, this seal is specifically tailored for the W126 chassis, which spans the model years from 1985 to 1996, encompassing the legendary **S-Class (S280, S320, S420, and S600)** as well as the **500 SEL and 560 SEC** variants. Crafted from high-quality elastomeric materials reinforced with durable synthetic fibers, the seal is engineered to withstand the extreme pressures, temperatures, and rotational forces generated by the powerful inline-six and V8 engines that powered these vehicles, including the legendary **3.8L M117, 5.0L M117, and 5.6L M117** engines, as well as the high-performance **5.0L M116** found in the S600.

This front crankshaft seal plays a critical role in preventing oil leakage from the engine s front cover, where the crankshaft passes through the timing cover housing. Over time, wear, heat, and vibration can compromise the seal s integrity, leading to oil drips, reduced lubrication efficiency, and potential damage to the timing belt, pulleys, and other critical components. The **A0039970347** seal is designed with a **metal-reinforced lip** and a **self-adjusting design**, allowing it to conform seamlessly to the crankshaft s surface while maintaining a tight, consistent seal under dynamic conditions. Its robust construction ensures resistance to oil degradation, ozone exposure, and thermal expansion, making it a long-lasting solution for both original equipment replacement (OEM) and aftermarket applications.

Installation of this seal requires careful attention to detail, as improper handling can lead to damage to the crankshaft or timing cover. Mercedes-Benz engineers have accounted for this by designing the seal with a **precise outer diameter** that matches the front cover s bore, ensuring a snug fit without excessive interference. The seal s **inner diameter** is meticulously calibrated to accommodate the specific crankshaft journal size of the W126 engine family, whether it be the **70mm or 75mm** journals found in the inline-six or V8 configurations. To further enhance durability, the seal incorporates a **backing ring** that prevents deformation during installation, while its **smooth, low-friction lip** minimizes wear on the crankshaft over extended service life.

For enthusiasts and mechanics restoring or maintaining a W126 S-Class, this seal is an essential part of preserving the vehicle s legendary performance and prestige. Whether used in a classic restoration project or as part of a routine maintenance overhaul, the **0039970347 A0039970347** ensures that the engine remains properly lubricated and free from leaks, allowing the iconic Mercedes-Benz powerplants to continue delivering the smooth, refined power that defined the S-Class era. Its compatibility with both **dry-sump and wet-sump** engine configurations further underscores its versatility, making it a must-have component for anyone committed to maintaining the highest standards of Mercedes-Benz engineering.

### **Pros and Cons of buying a Mercedes-Benz W126 S-Class Front Crankshaft Seal (Part Number: 0039970347 / A0039970347)**

1. **OEM Quality** This is an original equipment manufacturer (OEM) part, meaning it meets Mercedes-Benz s exact specifications for fit, function, and durability. OEM parts are designed to match the performance and longevity of factory-installed components, reducing the risk of premature failure.

2. **Reliability and Longevity** The W126 S-Class is a classic luxury vehicle, and its crankshaft seals were built to last under proper maintenance conditions. An OEM seal should provide reliable service for the life of the engine if installed correctly and the engine is well-maintained.

3. **Compatibility** This part is specifically designed for the W126 S-Class (1985 1991 models), ensuring a perfect fit without modifications. Using an aftermarket or non-OEM part risks misalignment or improper sealing, which could lead to leaks or damage.

4. **Warranty Coverage (if purchased from authorized dealers)** If you buy this part from an official Mercedes-Benz dealer or an authorized distributor, it may come with a limited warranty, providing peace of mind against defects.

5. **Prevents Engine Damage** A failing crankshaft seal can lead to oil leaks, which can contaminate the timing belt or chain, damage bearings, or cause catastrophic engine failure. Replacing it proactively can save thousands in repair costs.

6. **Resale Value** Keeping the vehicle in top condition with OEM parts helps maintain its value, especially for classic Mercedes-Benz models where authenticity is highly valued by collectors.

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1. **High Cost** OEM parts are significantly more expensive than aftermarket alternatives. The crankshaft seal for a W126 S-Class can cost **$100 $300 or more**, depending on the source. Labor costs for replacement can also be high, especially if requiring a professional mechanic.

2. **Limited Availability** While still available, OEM parts for older Mercedes models like the W126 may not be as widely stocked as they once were. You may need to order from specialty suppliers, which could extend lead times.

3. **Potential for Counterfeit Parts** If purchasing from non-authorized sellers (e.g., eBay, random online marketplaces), there is a risk of receiving a **counterfeit or low-quality part**. Always verify the seller s reputation and part authenticity.

4. **Installation Complexity** Replacing a crankshaft seal requires **disassembling the front of the engine**, which can be labor-intensive and time-consuming. DIYers without experience may struggle, and improper installation could lead to leaks or damage.

5. **Age-Related Wear** Even with an OEM seal, the rest of the engine may have **wear from age or neglect** (e.g., worn bearings, timing chain issues). Replacing just the seal may not fully resolve underlying problems, and further repairs could be needed soon after.

6. **Alternative Options May Be Cheaper** Aftermarket seals (e.g., from **Fel-Pro, Gates, or Bosch**) can be **30 50% cheaper** while still offering high quality. Some reputable brands use similar materials and manufacturing processes as OEM parts.

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The **Mercedes-Benz W126 S-Class OEM crankshaft seal (0039970347 / A0039970347)** is a **high-quality, reliable choice** if you prioritize **authenticity, longevity, and peace of mind**. It is the best option for maintaining the vehicle s original integrity and preventing costly engine damage. However, the **high cost and potential installation challenges** make it less ideal for casual DIYers or those on a tight budget.

If you are **not concerned about OEM authenticity** and want to save money, a **high-quality aftermarket seal** (e.g., Fel-Pro or Gates) is a **practical alternative** that offers similar performance at a lower price. Always ensure the aftermarket part is **properly rated for your engine type** (e.g., correct material for oil resistance).

For **classic car enthusiasts or collectors**, the OEM part is worth the investment to preserve the vehicle s value and heritage. For **daily drivers or budget-conscious owners**, an aftermarket seal may be the smarter financial choice.

- **If you value authenticity, longevity, and have the budget:** **Purchase the OEM seal from an authorized Mercedes-Benz dealer or a trusted specialty supplier** (e.g., **Mercedes-Benz Parts, Classic Mercedes Specialists, or eBay with verified sellers**).

- **If you want to save money but still ensure quality:** **Choose a reputable aftermarket seal (Fel-Pro, Gates, or Bosch)** and verify it matches your engine s specifications.

- **If attempting DIY installation:** **Research thoroughly or consult a mechanic** to avoid mistakes that could lead to leaks or damage. Consider having a professional install it if unsure.

- **Always inspect the rest of the engine** (timing chain/gear, bearings, oil leaks) before and after replacement to address any underlying issues.

Ultimately, the best choice depends on your **budget, priorities, and the vehicle s condition**. For a W126 S-Class, investing in the right seal whether OEM or high-quality aftermarket will help **extend the engine s life and maintain the car s performance**.

Details:

The seal is included in the package, and manufacturer part number. The product is a front crankshaft seal for Mercedes-Benz S-Class W126, manufactured by in Germany.

part #: 0039970347 prices

• $11.95-$55.41

specifications cranshafengin:

• for models: W126
• for makes: Mercedes
• mpn: 0039970347
• part type: Seal Crankshaft
• items included: Seal
• customs and taxes: No Customs Fees For Usa Customers
• country of origin: Germany
• reference oe/oem number: A0039970347

offer cranshafengin:

• sold: 0
• quantity: 1
• options: Ship-to-home
• availability: In Stock
• started: April 28, 2026
• best offers: True

seller cranshafengin:

• city: Silver Spring, Maryland
• rating: 100.0%
• # reviews: 95

returns cranshafengin:

• policy: No Returns

shipping cranshafengin:

• type: Fixed
• cost: $5.00
• transit: 4-10 Days
• service: USPS Ground Advantage
• carrier: USPS
• class: Standard

payments cranshafengin:

• wallet: Google-pay
• other
• credit card: Discover

general cranshafengin:

• Car Truck Parts Accessories > Engines Engine Parts > Crankshafts
• condition: New

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