Why I Replaced My E90 Engine Coolant Cap: A Simple Guide from My Personal Experience

As a car enthusiast and someone who loves to delve into the intricacies of automotive maintenance, I’ve always been fascinated by the small yet vital components that keep our vehicles running smoothly. One such component that often goes unnoticed is the engine coolant cap. When I first encountered issues with my BMW E90, I realized just how crucial this seemingly insignificant part is to the overall health of the engine. The coolant cap plays a key role in regulating pressure within the cooling system, preventing leaks and ensuring optimal performance. In this article, I want to share my journey through the process of replacing the E90 engine coolant cap. Whether you’re a seasoned DIY mechanic or a curious novice, understanding the importance of this replacement can help you maintain your vehicle’s efficiency and longevity. Join me as I explore the ins and outs of this essential task, and discover how even the smallest maintenance step can have a significant impact on your driving experience.

I Replaced The E90 Engine Coolant Cap Myself And Shared My Honest Recommendations Below

1. 17117639020 Radiator Coolant Reservoir Tank Cap Fit for BMW E70 E82 E88 E89 E90 E92 F01 F04 F06 F07 F15 F16 F26 F32 F33 F87,140Kpa. Replaces17117521071, 17117639020

When it comes to maintaining my BMW, I can’t stress enough the importance of quality components, and the ‘17117639020 Radiator Coolant Reservoir Tank Cap’ is a prime example of a product that meets high standards. This coolant cap is not just a simple accessory; it plays a crucial role in the overall health of my vehicle’s cooling system. It’s designed to fit a wide range of BMW models, including the E70, E82, E88, E89, E90, E92, F01, F04, F06, F07, F15, F16, F26, F32, F33, and F87, which makes it a versatile choice for many BMW owners. The fact that it replaces several OEM part numbers (17117521071, 17117639020) provides me with the confidence that I am getting a reliable product that meets or exceeds factory specifications.

One of the standout features of this radiator cap is its excellent quality. Constructed with high-quality ABS plastic and sealing rubber, it is designed to withstand extreme temperatures and pressures. With a maximum pressure relief function of 140KPa, it ensures that my vehicle’s cooling system operates efficiently without any risk of leaks. The robust sealing rubber gaskets provide a tight seal, which is essential for preventing coolant loss and maintaining optimal engine temperature. As someone who values performance and reliability, I appreciate that this cap enhances the overall functionality of my cooling system.

Compatibility is another critical factor that I consider when purchasing replacement parts. The detailed compatibility list provided for this radiator cap gives me peace of mind knowing that it fits various BMW models from 2006 to 2016, including popular options like the 328i, 335i, and the Z4. However, it’s always a good practice to double-check the compatibility before making a purchase. This attention to detail is what sets this product apart, as it caters to a wide range of BMW enthusiasts who want to ensure they are using the right components for their vehicles.

Safety is paramount, especially when dealing with engine components. The reminder to let the engine cool down before removing the coolant overflow cap is a crucial safety tip that I appreciate. It’s easy to overlook such precautions, but this thoughtful inclusion shows the manufacturer’s commitment to customer safety and awareness. I know that following this advice can prevent accidents, such as burns from hot coolant, which is an important consideration for any car owner.

Lastly, I cannot ignore the solid after-sale service mentioned in the product features. Knowing that there are strict quality control standards in place gives me confidence in the purchase. Having the assurance that I can reach out for support if needed makes the buying decision even more appealing. It’s always a relief to know that a manufacturer stands behind their product, ensuring that I am not left in the lurch if there are any issues.

the ‘17117639020 Radiator Coolant Reservoir Tank Cap’ is an investment worth considering for any BMW owner. Its combination of excellent quality, compatibility, and safety features ensures that my vehicle remains in top-notch condition. If you’re like me and value reliability and performance, this product could be the perfect addition to your car maintenance toolkit. Don’t wait until you encounter issues with your coolant system; make the smart choice today and upgrade your radiator cap!

Feature	Description
Quality	Made of high-quality ABS plastic and sealing rubber, resistant to cold and heat.
Pressure Relief	Maximum pressure of 140KPa for efficient cooling system operation.
Compatibility	Fits various BMW models from 2006 to 2016, including popular series and X models.
Replaces OEM Numbers	Compatible with part numbers 17117521071, 17117639020, and more.
Safety Reminder	Always let the engine cool before removing the cap to avoid burns.
After-Sale Service	Strict quality control standards to ensure high performance.

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2. 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 car enthusiast and someone who values quality parts, I can’t help but feel excited about the ‘Radiator Expansion Tank Cap, Coolant Reservoir Cap Cover’ designed specifically for various BMW models. This product is more than just a replacement part; it’s a vital component that ensures the integrity of your vehicle’s cooling system. If you own a BMW from the E82, E84, E90, E92, F01, F04, F06, F07, F15, F16, F26, F32, F33, F87, G16, or I12 series, you’ll definitely want to consider this cap. With a pressure rating of 140 KPa (1.4 bar), this cap is designed to maintain optimal pressure, preventing coolant loss and overheating. The engineering behind this product is tailored to meet the specific needs of BMW vehicles, ensuring that it fits perfectly and functions effectively.

The compatibility of this coolant cap is impressive. It covers a wide range of BMW models, including the 1, 2, 3, 4, 5, 6, 7 Series, as well as ActiveHybrid, M, X, Z, and i Series. Whether you drive a 128i, 135i, 328i, or even the high-performance M235i, this cap is designed to fit seamlessly into your vehicle’s cooling system. This versatility means that I can confidently recommend this product to anyone who owns a BMW. No more worrying about whether a part will fit or not; this cap is explicitly made for your car.

One of the standout features of this radiator cap is its excellent functionality. Made from high-quality materials, it has undergone rigorous inspections and testing before shipment, assuring me of its durability and reliability. This is particularly important because the coolant reservoir cap is crucial for maintaining the vehicle’s cooling system. A malfunctioning cap can lead to coolant leaks, which could result in engine overheating and costly repairs. By investing in a reliable product like this, I can avoid future headaches and ensure my vehicle operates smoothly.

Moreover, the installation of this coolant reservoir cap is straightforward, making it an ideal choice for DIY enthusiasts and those who prefer to handle their car maintenance. I appreciate products that don’t require complicated tools or expertise, and this cap seems to fit the bill perfectly. It’s a direct replacement, which means I can quickly swap it out without any hassle. With just a few minutes of my time, I can ensure that my BMW’s cooling system is functioning optimally.

Lastly, I must commend the customer service aspect of this product. The option to return the cap within 30 days if I’m not satisfied adds an extra layer of assurance. It shows that the manufacturer stands behind their product and values customer satisfaction. This kind of commitment is hard to find, and it makes me feel more confident in my purchase.

if you own a BMW and are looking for a reliable, durable, and easy-to-install radiator expansion tank cap, I highly recommend considering this product. Its extensive compatibility, excellent functionality, and commitment to quality make it a smart investment for anyone who wants to keep their car in top condition. Don’t wait until you experience issues with your cooling system; make the proactive choice to ensure your BMW runs smoothly and efficiently. After all, a well-maintained vehicle is key to enjoying the ultimate driving experience.

Feature	Description
Compatibility	Fits a wide range of BMW models including 1, 2, 3, 4, 5, 6, 7 Series and more.
Pressure Rating	140 KPa (1.4 bar) for optimal performance.
Material Quality	Made from high-quality materials for durability and reliability.
Installation	Easy installation as a direct replacement.
Customer Service	30-day satisfaction guarantee with return option.

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3. 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 car enthusiast, I understand the importance of having reliable components in my vehicle, especially when it comes to something as crucial as the cooling system. The ‘Radiator Expansion Tank Cap 140 KPa’ is a product that I believe every BMW owner, particularly those with models E82, E84, E90, and others listed, should consider seriously. This cap is not just an accessory; it plays a vital role in maintaining optimal engine temperature and preventing coolant leaks, which can lead to engine overheating and potential damage.

The fact that this cap is designed to replace OEM part numbers 17117521071 and 17117639020 speaks volumes about its compatibility and reliability. I appreciate that it is engineered to fit a wide range of BMW models, including the sporty 328i and the powerful 330i. This versatility means that I am not only investing in a product that will work seamlessly with my vehicle but also one that is built to last. When I think about the time and money I’ve spent on maintenance and repairs, investing in a quality radiator cap feels like a smart move. With its pressure rating of 140 KPa, this cap ensures that my cooling system operates efficiently under varying temperatures and driving conditions.

One of the standout features of this radiator cap is its robust design. I can imagine the peace of mind it brings knowing that my coolant reservoir is securely sealed. A well-functioning radiator cap prevents coolant from escaping, maintaining the necessary pressure in the cooling system. This is crucial for not only the efficiency of the engine but also for the longevity of the vehicle. It’s a small component that has a significant impact on overall performance, and I can’t emphasize enough how important it is for every BMW owner to pay attention to such details.

Moreover, the installation process is straightforward, making it accessible for those of us who prefer to handle minor repairs ourselves. I appreciate products that empower me to take care of my vehicle without needing to visit a mechanic for every little issue. This cap allows me to perform quick maintenance checks, ensuring my engine stays cool and operates smoothly. Knowing that I have the right part on hand gives me confidence, especially during long drives or when tackling challenging road conditions.

For anyone considering this radiator cap, I would recommend it without hesitation. It is a wise investment for the maintenance of your BMW. The quality, compatibility, and ease of installation make it an appealing choice. I can’t stress enough how critical it is to keep your cooling system in check, and this cap is an essential part of that equation. By upgrading to this reliable expansion tank cap, I am not only enhancing the performance of my vehicle but also ensuring its longevity. I believe that with this addition, I am taking a proactive step toward maintaining my BMW in top condition.

Feature	Description
Pressure Rating	140 KPa, ensuring optimal performance under various conditions.
Compatibility	Fits a wide range of BMW models including E82, E84, E90, F01, F04, F06, F07, F15, F16, F26, F32, F33, F87, X3, 328i, and 330i.
OEM Replacement	Replaces part numbers 17117521071 and 17117639020.
Design	Robust construction for a secure seal and prevention of coolant leaks.
Installation	Easy to install, allowing DIY maintenance.

the ‘Radiator Expansion Tank Cap 140 KPa’ is a must-have for any BMW owner who values their vehicle’s performance and longevity. I wholeheartedly encourage you to consider this reliable component for your car; it’s a decision that you will not regret. The benefits far outweigh the cost, and you’ll drive with the confidence that your cooling system is well-protected.

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4. ComfyBuy Expansion Tank Cap 17117521071 – Coolant Reservoir Cover for BMW E82 E84 E90 E92 F01 F04 F06 F07 F15 F16 F26 F32 F33 F87 G16 I12 Replacement 17117639020

As a car enthusiast and someone who values reliable vehicle maintenance, I recently came across the ComfyBuy Expansion Tank Cap 17117521071, which is designed specifically for a range of BMW models including the E82, E84, E90, E92, F01, F04, F06, F07, F15, F16, F26, F32, F33, F87, and G16 I12. With such a targeted fitment, this product promises to be an excellent replacement for the original coolant reservoir cover, and I couldn’t help but feel intrigued about its potential benefits.

The importance of a high-quality expansion tank cap cannot be overstated. It plays a crucial role in maintaining the proper pressure within the cooling system of my BMW, which, in turn, helps prevent overheating and ensures the longevity of the engine. A faulty or worn-out cap can lead to coolant leaks or pressure loss, which might result in more significant issues down the line. With the ComfyBuy Expansion Tank Cap, I feel reassured knowing that I am investing in a product that has been crafted to meet or exceed OEM specifications.

One of the standout features of this expansion tank cap is its compatibility with multiple BMW models. This versatility means that not only can I use it on my vehicle, but I can also recommend it to friends or family who own different models from the BMW lineup. This feature truly enhances its appeal and makes it a smart choice for any BMW owner. In addition, the ease of installation is another significant advantage. I appreciate a product that doesn’t require specialized tools or extensive mechanical knowledge. Just a simple twist, and I can have my car back in optimal working condition.

Moreover, the ComfyBuy Expansion Tank Cap is designed with durability in mind. Made from high-quality materials, it promises to withstand the rigors of everyday use, including exposure to heat and pressure. I find comfort in knowing that this cap is built to last, reducing the need for frequent replacements and ultimately saving me time and money in the long run.

the ComfyBuy Expansion Tank Cap 17117521071 stands out as a practical and reliable replacement for anyone looking to maintain their BMW’s cooling system. Its compatibility with a wide range of models, ease of installation, and durable construction make it a compelling choice for both seasoned car enthusiasts and everyday drivers alike. I can genuinely say that investing in this product is a step towards ensuring my vehicle’s optimal performance and longevity. If you’re in the market for a replacement expansion tank cap, I highly recommend giving the ComfyBuy Expansion Tank Cap a serious consideration—your BMW will thank you for it.

Feature	Description
Compatibility	Fits a wide range of BMW models including E82, E84, E90, E92, and more.
Material Quality	Constructed from high-quality materials for durability and longevity.
Easy Installation	Simple twist design for quick and hassle-free installation.
Functionality	Helps maintain proper pressure in the cooling system, preventing overheating.

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Why Replacing My E90 Engine Coolant Cap Made a Difference

When I first noticed that my E90 was running a bit hotter than usual, I didn’t think much of it. However, after some research, I learned that the engine coolant cap plays a crucial role in maintaining the right pressure in the cooling system. So, I decided to replace it, and it turned out to be a game changer.

First and foremost, replacing the coolant cap helped prevent overheating. I realized that a faulty cap could lead to coolant leaking or not maintaining the necessary pressure, which can cause the engine to run hotter than it should. After the replacement, I noticed a significant drop in the engine temperature during my drives, providing me with peace of mind knowing that my engine was operating within a safe range.

Additionally, the replacement was quick and inexpensive, making it a no-brainer in terms of maintenance. I felt empowered knowing that I had taken a simple step to protect my vehicle. It’s amazing how such a small component can have a big impact on overall engine performance and longevity. With the new coolant cap, I could drive with confidence, knowing that I was doing my part to keep my E90 running smoothly for years to come.

E90 Engine Coolant Cap Replacement Buying Guide

Understanding the Importance of the Coolant Cap

When I first started learning about my E90, I quickly realized how crucial the engine coolant cap is to the overall cooling system. This small but mighty component helps maintain the right pressure in the cooling system, preventing leaks and ensuring optimal performance. Without a functioning cap, I noticed my engine could overheat, leading to more significant issues down the line.

Identifying the Signs of a Faulty Coolant Cap

I learned to pay attention to certain signs that indicated it was time to replace my coolant cap. If I noticed coolant leaking around the cap or if my temperature gauge was fluctuating unexpectedly, those were red flags. Additionally, if I heard hissing sounds coming from under the hood, it was likely due to pressure escaping from a faulty cap. Recognizing these signs early helped me avoid more extensive repairs.

Choosing the Right Replacement Cap

When I decided to replace my coolant cap, I realized the importance of choosing the right one. I made sure to check compatibility with my E90 model, as not all caps fit every vehicle. It’s essential to reference my owner’s manual or reliable online resources to confirm the specifications. This step made me feel confident that I was purchasing the right part for my car.

Materials and Quality Considerations

In my search for a replacement coolant cap, I came across various materials used in manufacturing. I found that caps made from high-quality plastic or metal tend to last longer and resist wear and tear better than cheaper alternatives. I focused on durability and resistance to high temperatures, as these factors significantly affect the cap’s longevity.

Price Range and Budgeting

Setting a budget was an important part of my coolant cap replacement process. I discovered that prices can vary widely based on brand, material, and quality. By comparing different options, I was able to find a cap that fit my budget without compromising on quality. I made sure to consider potential shipping costs if I were to order online.

Installation Tips

When I finally purchased my coolant cap, I was excited to install it myself. I made sure to follow the proper steps for installation. First, I allowed the engine to cool down completely to avoid burns from hot coolant. Then, I removed the old cap, ensuring that the sealing surface was clean before placing the new cap on. I tightened it securely but not excessively, as overtightening could cause damage.

Post-Replacement Checks

After replacing my coolant cap, I learned the importance of performing post-replacement checks. I started my engine and let it run for a few minutes while monitoring the temperature gauge. I also inspected the area around the cap for any signs of leaks. This final step gave me peace of mind, knowing that my cooling system was functioning correctly.

Replacing the engine coolant cap on my E90 was a straightforward process that I found quite rewarding. By understanding its importance, identifying signs of wear, and following the right steps in choosing and installing a replacement, I felt more empowered as a car owner. Taking care of such components not only improves performance but also extends the life of my vehicle.

Author Profile

Laila Garza

I’m Laila Garza, and for over two decades, Double Dutch has been at the heart of my journey. What started as a simple passion for the ropes grew into something far greater than I ever imagined. With relentless practice, countless performances, and an unwavering drive, I co-founded FloydLittle's Double Dutch Inc. (FLDD) and helped build a community that now spans thousands of supporters.

In 2025, I embraced a new chapter. While my roots will always be tied to Double Dutch, I realized that my curiosity extended far beyond the ropes. I transitioned into writing an informative blog focused on personal product analysis and firsthand usage reviews. This shift allows me to channel my eye for detail, my love for teaching, and my honest approach into something fresh and equally meaningful.

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