DORMAN OE SOLUTIONS 603-256 Coolant Reservoir Csw 11990632-101

( Brand: Dorman Oe Solutions ), ( Manufacturer Part Number: 603-256 ), ( Manufacturer Warranty: 1 Year ), ( Ipn: 11990632-101 ), ( California Prop 65 Warning: Prop65 Warning )

Review DORMAN OE SOLUTIONS Mercedes Coolant Reservoir fits ML350 ML500 GL320 GL450 GL550

The **Dorman 603-256 Coolant Reservoir** is a high-quality, direct-fit replacement part designed specifically for Mercedes-Benz models including the **ML350, ML500, GL320, GL450, GL550, and GL550 4matic**, ensuring optimal performance and reliability for these premium SUVs. Engineered to meet or exceed OEM specifications, this reservoir is crafted from durable, temperature-resistant materials that maintain structural integrity under the demanding conditions of modern engine cooling systems. Its sleek, black plastic construction not only blends seamlessly with the vehicle s under-hood aesthetics but also provides a secure, leak-proof fit, preventing coolant loss and potential overheating issues. The reservoir features a robust, threaded cap with a pressure relief valve, designed to regulate system pressure and prevent coolant evaporation while ensuring proper circulation through the engine bay. This component is a critical part of the vehicle s cooling system, helping to maintain optimal engine temperatures and extend the lifespan of the radiator, water pump, and hoses. Whether replacing a worn-out original part or upgrading for enhanced durability, the Dorman 603-256 offers a dependable, long-lasting solution that aligns with Mercedes-Benz s high-performance standards. Built to withstand the rigors of daily driving, frequent highway use, or towing demands, this reservoir is an essential component for owners seeking peace of mind and long-term reliability in their luxury vehicles.

### **Pros and Cons of buying a Dorman 603-256 Coolant Reservoir for Mercedes-Benz Models (ML350, ML500, GL320, GL450, GL550, GL550 4Matic)**

1. **Direct Fitment** The Dorman 603-256 is specifically designed as an OEM replacement for the coolant reservoir in the listed Mercedes-Benz models, ensuring compatibility without modifications.

2. **Quality Materials** Dorman is a well-known aftermarket brand that uses durable materials, reducing the risk of leaks or premature failure compared to cheaper generic alternatives.

3. **Easy Installation** The part is designed for straightforward replacement, requiring only basic tools and minimal mechanical skill. No special equipment or expertise is needed.

4. **Cost-Effective** Compared to purchasing an OEM (original equipment manufacturer) part directly from Mercedes-Benz, the Dorman reservoir is significantly cheaper while maintaining reliability.

5. **Warranty Coverage** Dorman parts often come with a manufacturer s warranty (typically 1 2 years), providing some protection against defects.

6. **Compatibility with Common Coolant Types** Works with Mercedes-approved coolant (e.g., Mercedes-Licensed Glysantin or Dex-Cool), ensuring proper system function.

7. **Prevents Cooling System Issues** A failing reservoir can lead to overheating or coolant loss; replacing it proactively avoids potential engine damage.

1. **Not OEM Quality** While functional, the Dorman part may not match the exact build quality, finish, or longevity of a genuine Mercedes-Benz reservoir. Some owners report slight differences in plastic rigidity or fit.

2. **Potential Fitment Variations** In rare cases, slight differences in mounting or hose connections may require minor adjustments, especially if the vehicle has been previously modified or if the reservoir was previously replaced.

3. **Limited Brand Recognition** Mercedes-Benz dealerships may not stock or recommend Dorman parts, which could be a concern for owners who prefer OEM or dealership-approved components.

4. **No Long-Term Data on Specific Models** While Dorman is reliable, long-term performance on these particular Mercedes models (especially the GL/ML series) may not have as extensive a track record as OEM parts.

5. **Price Sensitivity** Some buyers may perceive the Dorman part as "cheap" compared to OEM, though the price difference is usually negligible compared to the cost of engine repairs from coolant system failure.

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The **Dorman 603-256 coolant reservoir** is a **strong, cost-effective choice** for replacing the reservoir in your Mercedes-Benz ML350/ML500/GL320/GL450/GL550. It offers **direct fitment, durability, and ease of installation** while avoiding the higher cost of OEM parts. For most owners, the **pros outweigh the cons**, making it a practical and reliable upgrade.

However, if you prioritize **absolute OEM quality, warranty support from a dealership, or have concerns about long-term reliability**, purchasing an **authentic Mercedes-Benz replacement part** (e.g., from a dealer or authorized supplier) may be preferable though at a significantly higher cost.

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- **For most DIYers or budget-conscious buyers:** **Go with the Dorman 603-256.** It s a well-regarded aftermarket part that will serve the purpose without major drawbacks.

- **For owners seeking maximum reliability or warranty coverage:** **Opt for an OEM or dealership-approved replacement**, especially if you plan to keep the vehicle long-term.

- **Additional Tip:** Always **flush the cooling system** when replacing the reservoir to remove old coolant and contaminants, ensuring optimal performance of the new part.

A well-maintained cooling system is critical for Mercedes engines, and this reservoir is a **safe, affordable choice** to keep yours running smoothly.

Details:

Premium Parts: All parts are premium ISO/TS 16949 quality. Part Number:603-256. Warranty:1 Year. Condition: NEW.

This Engine Coolant Reservoir is manufactured and tested to the strictest OE car truck standards for unparalleled performance. Tested and Approved: Each part is run through rigorous testing before it leaves the factory. Brand:Dorman - OE Solutions. Technical Specifications: Part Type:Engine Coolant Reservoir.

Built for trouble-free ownership and 100% visually inspected quality tested, this Engine Coolant Reservoir is backed by our satisfaction guarantee.

part #: 603256 prices

• $50.00-$127.41

specifications ocoosys:

• for models: Ml350, Ml500, Gl320, Gl450, Gl550
• for makes: Mercedes
• brand: Dorman Oe Solutions
• mpn: 603-256
• manufacturer warranty: 1 Year
• ipn: 11990632-101
• california prop 65 warning: Prop65 Warning

offer ocoosys:

• quantity: 5
• sold: 0
• options: Ship-to-home
• availability: In Stock
• started: June 1, 2026

payments ocoosys:

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

general ocoosys:

• Car Truck Parts Accessories > Engine Cooling Components > Other Engine Cooling Components
• condition: New

shipping ocoosys:

• service: Standard, Expedited, Overnight
• cost: $0.00
• transit: 2-4 Days
• type: Fixed
• class: Standard, Expedited, One-day

returns ocoosys:

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

seller ocoosys:

• rating: 99.0%
• city: Hebron, Kentucky
• # reviews: 19764

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