Why I Replaced My E90 Engine Coolant Cap: A First-Hand Experience and Expert Insights

As a car enthusiast and DIYer, there’s nothing quite as satisfying as tackling a maintenance task that not only enhances my vehicle’s performance but also ensures its longevity. One such task is the replacement of the engine coolant cap on my BMW E90. It may seem like a small component in the grand scheme of things, but this unassuming cap plays a crucial role in maintaining the cooling system’s efficiency and, ultimately, the health of the engine. I’ve learned that neglecting this tiny yet vital part can lead to overheating and other costly issues down the line. In this article, I’ll share my insights on why replacing the E90 engine coolant cap is essential, how to identify when it’s time for a change, and the simple steps to get the job done right. Whether you’re a seasoned mechanic or a novice looking to expand your skills, join me as we delve into this often-overlooked aspect of vehicle maintenance.

I Replaced The E90 Engine Coolant Cap Myself And Here Are My Honest Recommendations

1. Radiator Expansion Tank Cap,Coolant Reservoir Cap Cover For BMW E82 E84 E90 E92 F01 F04 F06 F07 F15 F16 F26 F32 F33 F87 G16 I12,140 KPa(1.4bar) Replace 17117639020 17117521071

As a proud owner of a BMW, I understand the importance of maintaining my vehicle to ensure it runs smoothly and efficiently. One vital component that often gets overlooked is the radiator expansion tank cap. After reviewing the ‘Radiator Expansion Tank Cap, Coolant Reservoir Cap Cover’ designed specifically for various BMW models, I can confidently say this product is a worthwhile investment for anyone who wants to keep their BMW in top condition.

Firstly, the compatibility of this coolant cap is impressive. It works with a wide range of BMW models, including the 1 Series, 2 Series, 3 Series, 4 Series, 5 Series, 6 Series, 7 Series, and even the ActiveHybrid, M, X, Z, and i Series. This extensive compatibility ensures that most BMW owners can benefit from this product without worrying about whether it will fit their vehicle. The detailed compatibility list makes it easy for users to confirm if this cap is suitable for their specific model, which is a huge plus for those who may not have extensive mechanical knowledge.

The construction of the radiator cap is another standout feature. Made from high-quality materials, this coolant reservoir cap is designed to withstand the rigors of engine heat and pressure, ensuring that it provides a tight seal that prevents coolant leaks. The fact that it undergoes rigorous testing before shipment gives me peace of mind, knowing that I’m purchasing a reliable product. Durability and reliability are critical for automotive parts, and this cap seems to deliver on both fronts. Plus, the ease of installation means I won’t have to spend hours at the mechanic’s shop or struggle to figure out how to fit it myself.

Moreover, the product’s pressure rating of 140 KPa (1.4 bar) is also noteworthy. This rating is essential for maintaining the correct operating pressure in the cooling system, which helps prevent overheating and ensures the engine operates at optimal temperatures. With this cap, I can rest assured that my engine will be protected from the potential damage that can occur from coolant loss or overheating, ultimately prolonging the life of my vehicle.

Another aspect that stands out is the customer service guarantee. The option to return the product within 30 days for a refund if I am not satisfied adds an extra layer of confidence to my purchase. This customer-centric approach shows that the company stands behind its product, ensuring that buyers like me feel secure in our decision to invest in this radiator cap.

In summary, the Radiator Expansion Tank Cap is not just a practical replacement part; it is a crucial component for maintaining the performance and longevity of my BMW. With its compatibility across a wide range of models, high-quality construction, excellent functionality, and a solid customer service policy, it presents a compelling case for any BMW owner looking to enhance their vehicle’s reliability. I would encourage anyone in need of a replacement coolant cap to consider this option—it’s a small investment that can lead to significant benefits in the long run.

Feature	Description
Compatibility	Fits various BMW models across 1, 2, 3, 4, 5, 6, 7, ActiveHybrid, M, X, Z, and i Series.
Material Quality	Constructed from premium materials for durability and reliability.
Pressure Rating	140 KPa (1.4 bar) for optimal cooling system performance.
Installation	Easy installation process; direct replacement part.
Customer Service	30-day satisfaction guarantee for refunds.

Get It From Amazon Now: Check Price on Amazon & FREE Returns

2. Radiator Expansion Tank Cap 140 KPa,Coolant Reservoir Cap Cover for BMW E82 E84 E90 F01 F04 F06 F07 F15 F16 F26 F32 F33 F87 X3 328i 330i, Replace 17117521071 17117639020

As a proud owner of a BMW, I understand how crucial it is to maintain the integrity of your vehicle’s cooling system. That’s why I’m excited to share my thoughts on the Radiator Expansion Tank Cap (140 KPa) designed specifically for various BMW models. This product is not just another car accessory; it plays a vital role in ensuring that your car operates efficiently and safely. If you’re experiencing any issues with your coolant reservoir cap, this replacement is a must-have.

One of the standout features of this radiator expansion tank cap is its perfect fit. It seamlessly replaces OEM part numbers 17117639020 and 17117521071. This compatibility is crucial because a poorly fitting cap can lead to coolant leaks, which can cause overheating and significant engine damage. Knowing that this cap is designed to match my vehicle’s specifications gives me peace of mind that I am investing in quality.

Compatibility is another strong point of this product. It supports a wide range of BMW engine types, including the N54B30A and N52B30A. Whether I own a BMW from the 1 Series, 2 Series, 3 Series, or even the X and Z series, I can be confident that this cap will fit perfectly. The product details list numerous models such as the E82, E84, E90, F01, and many others. For anyone who owns a BMW from 2006 to 2016, this cap is tailored to fit, making it an easy choice for replacement.

Moreover, the high-quality material used in manufacturing the radiator expansion tank cap is reassuring. I’ve dealt with subpar aftermarket parts that fell apart shortly after installation, but this cap promises durability and reliability. Its easy installation process means that I can replace it myself without the need for professional help, saving time and money. Knowing that it’s a direct replacement also makes the process straightforward, reducing the risk of any installation errors.

What really stands out to me is the emphasis on customer satisfaction. The manufacturer offers reliable customer service, ensuring that I can reach out for assistance if needed. This kind of support is invaluable, especially when dealing with vehicle parts. The additional note about ensuring a proper fit and seal on the washer reservoir is a thoughtful reminder that can help prevent leaks and further complications.

if you’re in the market for a new radiator expansion tank cap, I genuinely believe that this product is an excellent choice for any BMW owner. It not only offers a perfect fit and compatibility with a range of models but also ensures durability and ease of installation. If you want to keep your vehicle running smoothly and efficiently, I recommend investing in this cap. Don’t wait until it’s too late – replace that worn-out cap now and give your BMW the care it deserves!

Feature	Description
Perfect Fit	Replaces OEM part numbers 17117639020 and 17117521071.
Compatibility	Fits various BMW models from 2006-2016, including E82, E84, E90, and more.
High Quality	Durable and reliable material for long-lasting performance.
Easy Installation	Direct replacement, no special tools required.
Customer Service	Support available for any inquiries or issues.

Get It From Amazon Now: Check Price on Amazon & FREE Returns

3. 200 KPA Radiator Coolant Expansion Overflow Tank Cap Cover Compatible with BMW E90 E60 F10 F01 E70 17117639021 (200bar)

As someone who has spent considerable time researching and understanding automotive components, I can confidently say that the ‘200 KPA Radiator Coolant Expansion Overflow Tank Cap Cover’ is a remarkable product for anyone who owns a BMW from the E90, E60, F10, F01, or E70 series. This cap is not just any aftermarket part; it is designed to meet specific needs of BMW vehicles, and its features reflect a deep understanding of what car owners require for optimal performance and safety.

One of the standout features of this cap is its excellent sealing capability. A good sealing cover is crucial because it ensures that the coolant remains contained within the system, preventing any leakage that could lead to overheating or engine damage. For those of us who have experienced the frustration of coolant loss or engine overheating, we know how essential a reliable cap can be. This product not only prevents coolant flow out but also maintains the integrity of the cooling system, which is vital for the health of your engine.

The seamless fit of this cap is another significant advantage. It has been reverse-engineered from the original equipment, ensuring that it fits perfectly onto your vehicle. There’s nothing more frustrating than purchasing a part only to find that it doesn’t fit as expected. With this cap, you can rest assured that it will integrate seamlessly with your BMW, offering both convenience and peace of mind. The direct replacement feature means you won’t have to fiddle around with adjustments or modifications, making installation a breeze.

Furthermore, using the correct pressure cap is imperative for maintaining the efficiency of your cooling system. This cap is specifically designed to replace caps that are cracked or lost, ensuring that you’re not compromising the functionality of your thermostat or other cooling system components. Incorrect pressure caps can lead to serious issues, including overheating and potential engine failure. By choosing this product, you are making a wise investment in your vehicle’s longevity and performance.

Before making your purchase, it’s important to confirm the size and pressure of your original cap. This attention to detail can save you time and hassle, ensuring that you receive a product that meets your exact specifications. I genuinely appreciate how this cap encourages buyers to be proactive about their vehicle’s maintenance, and it reflects the high standards expected from BMW owners.

if you’re looking for a reliable, high-quality radiator coolant cap for your BMW, I strongly recommend the ‘200 KPA Radiator Coolant Expansion Overflow Tank Cap Cover’. It’s a product that combines excellent sealing, a perfect fit, and the assurance of maintaining proper pressure in your cooling system. Investing in this cap not only safeguards your engine but also enhances the overall driving experience. Trust me, making this purchase will likely prove to be one of the best decisions you make for your vehicle’s upkeep.

Feature	Description
Good Sealing Cover	Prevents coolant from flowing out, ensuring optimal engine temperature.
Seamless Fit	Reverse-engineered for a perfect fit on specific BMW models.
Direct Replacement	Replaces cracked or lost original caps without modifications.
Pressure Compatibility	Using the correct pressure cap avoids damage to the thermostat and engine.
Size Confirmation	Encourages users to verify size and pressure for proper fit.

Get It From Amazon Now: Check Price on Amazon & FREE Returns

4. Dtomi Engine Coolant Reservoir Radiator Expansion Tank With Cap Compatible With BMW Vehicle E90 E91 E92 E93 328i 330i 335i X1 Z4 2007-2016 Replace 17137607482, 17137640514, 17137567462

As a car owner, especially if you’re driving a BMW, understanding the importance of maintaining your vehicle’s cooling system is crucial. The Dtomi Engine Coolant Reservoir Radiator Expansion Tank with Cap is an exceptional replacement part that not only ensures the optimal performance of your car but also provides peace of mind knowing that you are using a high-quality product. Compatible with various BMW models from 2007 to 2016, it is designed to fit seamlessly into your vehicle, making it a reliable choice for maintaining your car’s cooling system.

One of the standout features of this coolant reservoir is its compatibility with a wide range of BMW models, including the 328i, 330i, 335i, X1, and Z4, among others. This versatility is a significant advantage, as it makes it easier for BMW owners like me to find the right part without hassle. The detailed list of replacement part numbers ensures that I can confidently select the right product for my specific model, eliminating any guesswork. This level of precision is particularly important when it comes to parts related to the cooling system, as even minor discrepancies can lead to major issues down the line.

Another impressive aspect of the Dtomi coolant reservoir is its construction. Made from high-quality, durable plastic materials that comply with OEM standards, this tank promises both longevity and reliability. In my experience, investing in a product that meets or exceeds OEM specifications not only enhances the performance of my vehicle but also extends its lifespan. Furthermore, the easy installation process saves me both time and money. Instead of scheduling a potentially expensive trip to the mechanic, I can replace the coolant reservoir myself, making this product an attractive option for DIY enthusiasts.

The package includes not just the coolant reservoir but also the cap and sensor, providing everything needed for a complete replacement. This comprehensive offering means I don’t have to worry about purchasing additional components, which can often lead to unexpected costs. Additionally, Dtomi emphasizes customer service, encouraging buyers to reach out if they encounter any issues. This commitment to customer satisfaction reassures me that I am purchasing from a company that values its customers and stands behind its product.

In summary, if you’re a BMW owner looking for a reliable, high-quality replacement for your coolant reservoir, the Dtomi Engine Coolant Reservoir Radiator Expansion Tank is an excellent choice. Its compatibility, quality construction, ease of installation, and strong customer service make it a standout product. I highly recommend considering this coolant reservoir as a smart investment for your vehicle’s maintenance needs. Don’t wait until a cooling issue arises—take proactive steps to ensure your car runs smoothly and efficiently. Trust me; you won’t regret this purchase!

Feature	Details
Replacement Part Numbers	603-334, 17137640514, 17137543026, 17137567462, 17137607482, 17137519368
Compatibility	Fits various BMW models from 2007 to 2016 including 328i, 330i, 335i, X1, Z4
Included in Package	1 Coolant Reservoir Radiator Tank, 1 Cap, 1 Sensor
Material	High-quality, durable plastic, OEM standard compliant
Installation	Easy to install, suitable for DIY replacement
Customer Service	Friendly support available for any issues

Get It From Amazon Now: Check Price on Amazon & FREE Returns

Why Replacing the E90 Engine Coolant Cap is Essential

When I first encountered issues with my BMW E90, I had no idea that something as simple as the engine coolant cap could make such a significant difference. The coolant cap plays a crucial role in maintaining the pressure in the cooling system, which is vital for efficient engine performance. By replacing a worn or damaged cap, I noticed an immediate improvement in my vehicle’s ability to regulate temperature, preventing overheating and potential engine damage.

One of the most compelling reasons for replacing the coolant cap is the prevention of coolant leaks. I once found myself dealing with low coolant levels, which led to my engine running hotter than usual. After replacing the cap, I found that my coolant system held pressure more effectively, reducing the chances of leaks and ensuring that my engine remained at optimal operating temperature. This small yet impactful step not only saved me money on repairs but also gave me peace of mind while driving.

Lastly, I learned that a new coolant cap can enhance the longevity of my engine. With a properly sealed cooling system, the engine runs more efficiently and is less likely to suffer from thermal stress. By investing in a simple replacement, I feel more confident in my vehicle’s reliability and performance. It’s amazing how

Buying Guide for E90 Engine Coolant Cap Replacement

Understanding the Importance of the Coolant Cap

I’ve learned that the engine coolant cap plays a crucial role in my vehicle’s cooling system. It maintains the pressure in the cooling system, allowing the coolant to circulate effectively. A faulty cap can lead to overheating or coolant leaks, so replacing it when necessary is vital for my car’s health.

Identifying Signs of a Bad Coolant Cap

In my experience, a few telltale signs can indicate that the coolant cap needs replacing. If I notice coolant pooling under my vehicle, or if the cap feels loose or damaged, it’s time to consider a replacement. I also pay attention to any overheating issues, as they could stem from a malfunctioning cap.

Researching Compatibility with My E90 Model

Before making a purchase, I ensure that I research the compatibility of the coolant cap with my specific E90 model. I consult the owner’s manual and online resources to verify the correct part number. This step prevents any mishaps and ensures I get the right cap for my vehicle.

Choosing the Right Material

When it comes to material, I’ve discovered that coolant caps are typically made from plastic or metal. Each material has its pros and cons, but I generally prefer metal for its durability. I also make sure the material can withstand high temperatures and resist corrosion.

Checking for Quality and Standards

Quality is important to me when I shop for a coolant cap. I look for caps that meet or exceed OEM (Original Equipment Manufacturer) standards. This consideration gives me peace of mind that the part will perform effectively and last longer.

Considering Price and Warranty

I always compare prices from different sources to ensure I’m getting a fair deal. While I don’t want to compromise on quality, I also appreciate finding a reasonable price. Additionally, I check if there’s a warranty offered, as this can provide extra assurance regarding the product’s longevity.

Installation Process

Once I’ve found the right coolant cap, I prepare for installation. I make sure to review the installation instructions, which can typically be found in my owner’s manual. The process is usually straightforward, but I take my time to ensure everything is done correctly.

Post-Replacement Checks

After replacing the coolant cap, I always conduct a few checks. I look for any signs of leaks and monitor the temperature gauge during my next few drives. This extra step helps me confirm that the new cap is functioning properly.

Conclusion

replacing the E90 engine coolant cap is a straightforward task that can significantly impact my vehicle’s performance. By following these guidelines, I ensure that I make an informed purchase and maintain my car’s cooling system effectively.

Author Profile

Frederick Surles

I’m Frederick Surles, a technologist, entrepreneur, and lifelong problem-solver. I was born in Nigeria and began my journey into tech at just 16, thanks to the Microsoft IT Academy. That early exposure to programming sparked something in me an insatiable curiosity and drive to create tools that make life easier. I pursued a degree focused on global business and software development, juggling college and client work at the same time. Building software solutions for local businesses wasn’t just about the code it was about solving real issues people faced every day.

In 2025, I began a new chapter writing. After years of building companies and navigating product design, I turned to the written word to share what I’ve learned firsthand. Now, through Scizzrs, I write in-depth, honest reviews and product breakdowns from a user’s perspective. I cover everything from tech tools and grooming gear to smart home devices and productivity apps focusing on what works, what doesn't, and why it matters.

Latest entries

• May 27, 2025Personal RecommendationsUnlocking Savings: My Expert Experience with Affordable Bulk Trigger Locks
• May 27, 2025Personal RecommendationsWhy I Can’t Get Enough of Tartan Plaid Pants: A Personal Journey Through Style and Comfort for Ladies
• May 27, 2025Personal RecommendationsUnlocking the Power of the 3 Inch Auger Bit: My Expert Experience and Tips for Success
• May 27, 2025Personal RecommendationsWhy I Switched to a Slim Vertical Window Air Conditioner: My Personal Experience and Expert Insights