How I Successfully Replaced My E90 Engine Coolant Cap: A Step-by-Step Guide from My Personal Experience

When I first encountered issues with my BMW E90, the little things like the engine coolant cap seemed insignificant—just a minor detail in the grand scheme of car maintenance. However, I quickly learned that this unassuming component plays a crucial role in the overall health of my vehicle’s cooling system. The engine coolant cap not only helps maintain the proper pressure within the cooling system but also prevents coolant loss and potential overheating. In this article, I’m excited to share my journey of replacing the E90 engine coolant cap, highlighting the importance of this often-overlooked part and offering insights into why keeping it in top condition can save you from costly repairs down the road. Whether you’re a seasoned DIYer or just starting out on your automotive maintenance journey, understanding the nuances of this replacement can empower you to take better care of your beloved ride.

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

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 I first came across the ‘17117639020 Radiator Coolant Reservoir Tank Cap,’ I was impressed by its thoughtful design and robust features, especially for BMW owners. This product is specifically engineered to fit a wide range of BMW models from 2006 to 2016, including popular ones like the 328i, 335i, and Z4. If you own a BMW in this range, you’ll understand how crucial it is to maintain the integrity of your vehicle’s cooling system, and this cap plays a vital role in that.

The first thing that stands out to me is the excellent quality of materials used in this coolant cap. It boasts a maximum pressure relief function of 140KPa, which is essential for preventing overheating and maintaining optimal engine performance. The use of high-quality ABS plastic and sealing rubber means that this cap is not only durable but also resistant to both cold and heat. This resilience ensures that it will withstand the varying temperatures that your engine experiences without compromising its performance. The high-quality sealing rubber gaskets further enhance its capability to provide a tight seal, effectively preventing any leakage from your radiator tank. This is a critical feature that can save you from costly coolant loss and potential engine damage.

Compatibility is another strong point of this product. The fact that it fits various BMW models from 2008 to 2013, including the 128i, 135i, 328i, and many more, means that it caters to a significant number of BMW enthusiasts. It’s crucial to check the compatibility before purchase, and the product description provides a clear list to help confirm that this cap will fit your vehicle perfectly. This attention to detail is something I appreciate as a user, as it minimizes the chances of ordering the wrong part.

Moreover, it’s essential to mention the importance of following safety guidelines when handling this cap. The instructions to allow the engine to cool down before removing the coolant overflow cap are not just suggestions; they are vital safety precautions. Ignoring this can lead to severe burns from hot coolant, something no car owner wants to experience. This aspect of the product shows that the manufacturer cares about the safety of its users, which is a significant plus in my book.

Lastly, the commitment to quality is further emphasized by the after-sale service provided. With strict quality control standards in place, I feel reassured about the product’s performance. If any issues arise, knowing that there is dedicated support available can make a considerable difference, especially for someone who may not be a car expert.

the ‘17117639020 Radiator Coolant Reservoir Tank Cap’ is an outstanding choice for BMW owners looking for a reliable and high-quality replacement part. Its excellent construction, compatibility with a range of models, and user safety considerations make it a compelling option. If you’re currently facing issues with your coolant cap or simply want to ensure your vehicle runs smoothly, I would strongly recommend considering this product. It’s a small investment for the peace of mind it brings, especially when it comes to the health of your engine.

Feature	Description
Maximum Pressure Relief	140KPa for preventing overheating
Material	High-quality ABS plastic and sealing rubber
Compatibility	Fits various BMW models from 2006-2016
Safety Precaution	Allow engine to cool before removal
After-sale Service	Strict quality control and dedicated support

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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

When it comes to maintaining the performance and longevity of my BMW, I’ve come to appreciate the importance of quality parts. One product that stands out in this regard is the ‘Radiator Expansion Tank Cap, Coolant Reservoir Cap Cover’ designed for a wide range of BMW models including the E82, E84, E90, E92, F01, F04, F06, F07, F15, F16, F26, F32, F33, F87, G16, and I12. This product is not just a replacement part; it’s a commitment to ensuring that my vehicle runs smoothly and efficiently, providing peace of mind every time I hit the road.

One of the most compelling aspects of this coolant cap is its compatibility with numerous BMW models. Whether I own a 1 Series M from 2011, a 3 Series from 2006 to 2017, or a 5 Series from 2012 to 2016, this cap fits seamlessly. The extensive compatibility list means that I don’t need to worry about whether this product will work with my specific vehicle model. Instead, I can focus on the essential aspects of my car’s maintenance without the hassle of searching for multiple parts.

The features of this radiator expansion tank cap are impressive. It boasts a pressure rating of 140 KPa (1.4 bar), which is vital for maintaining the appropriate pressure in the cooling system. This ensures that the engine coolant is effectively circulated, preventing overheating and potential engine damage. The high-quality materials used in its construction contribute to its durability and reliability, allowing me to trust that this cap will perform well under pressure and last for the long haul.

Another significant benefit is the meticulous inspection process that each cap undergoes before shipment. Knowing that the product has been tested multiple times gives me confidence in its performance. It’s reassuring to know that the coolant reservoir cap I am purchasing has passed stringent quality checks, reducing the risk of future issues and enhancing my overall driving experience.

Furthermore, the installation process is straightforward, making it accessible even for those who might not consider themselves mechanically inclined. I appreciate that I can easily replace the cap without needing professional assistance, saving time and money. This ease of installation is particularly beneficial for someone like me who values efficiency in vehicle maintenance.

Customer service also plays an essential role in my purchasing decisions. The promise of a 30-day refund policy if I am not satisfied adds another layer of confidence. It shows the manufacturer’s commitment to quality and customer satisfaction, which is something I always look for when buying automotive parts.

the ‘Radiator Expansion Tank Cap’ is an excellent investment for any BMW owner. Its compatibility with numerous models, high-quality construction, and ease of installation make it a standout option in the market. If you’re looking to maintain your BMW’s performance and ensure its longevity, I strongly encourage you to consider this coolant cap. It’s not just a purchase; it’s a proactive step towards enhancing your vehicle’s reliability and efficiency.

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 coolant system performance.
Quality Assurance	100% inspected and tested for durability and reliability.
Installation	Direct replacement with easy installation process.
Customer Satisfaction	30-day refund policy if not satisfied.

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3. Radiator Expansion Tank Cap Coolant Reservoir Cap For BMW 328i 2007-2016 330i 2016-2018 Replace 17117639020 17117521071

As a BMW enthusiast and owner, I understand the importance of maintaining my vehicle in peak condition. One crucial component that often gets overlooked is the radiator expansion tank cap, especially for models like the BMW 328i from 2007-2016 and 330i from 2016-2018. The ‘Radiator Expansion Tank Cap Coolant Reservoir Cap’ is not just a replacement part; it’s a vital element that ensures the coolant system operates effectively, preventing overheating and ensuring that my engine runs smoothly.

What truly stands out about this product is its compatibility with a wide range of BMW models. This expansion tank cap fits various series, including the 1, 2, 3, 4, 5, 6, M, and X series. Whether I own a sporty 135i E82 or a robust X3, I can be confident that this cap will fit seamlessly. This versatility is a significant plus for anyone who may own multiple BMWs or is considering a future purchase. The detailed compatibility list makes it easy to verify that I am choosing the right part for my vehicle, eliminating any guesswork.

The part number is another reassuring factor for me; with references like 17117639020 and 17117521071, I can easily cross-check and ensure that I am purchasing the correct replacement for my specific model. In a world where online shopping can sometimes lead to errors in part selection, having a clear part number helps me make an informed decision, reducing the risk of buying the wrong product.

One of the most compelling features of this coolant reservoir cap is its design for direct replacement. Unlike generic parts that may require adjustments or modifications, this cap is a straightforward swap for the original broken or cracked parts. It’s a simple solution that saves time and effort—something I always appreciate, especially if I am trying to maintain my vehicle’s performance without unnecessary hassle. Just a quick installation, and I can have peace of mind knowing my coolant system is sealed properly, preventing any leaks that could lead to costly repairs down the line.

In addition, the package includes one coolant reservoir cap cover, meaning I get exactly what I need without any unnecessary extras. This straightforward approach aligns with my preferences as a consumer who values efficiency and practicality. Given that the cap plays a crucial role in the overall health of my vehicle’s engine, investing in a quality replacement is not just wise but essential.

if you’re a BMW owner like me, this Radiator Expansion Tank Cap is a must-have. It not only ensures that your cooling system functions properly but also offers compatibility across various models, making it a versatile choice. With its direct replacement capability and clear part numbers, I genuinely feel confident in recommending this product. Don’t wait until a small issue escalates into a major problem—consider making this investment for your BMW today!

Feature	Description
Compatibility	Fits various BMW models including 1, 2, 3, 4, 5, 6, M, and X series.
Part Numbers	17117639020, 17117521071, 17-11-7-639-020.
Replacement Type	Direct replacement for original broken or cracked parts.
Package Contents	1 PCS Coolant Reservoir Cap Cover.

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4. 200 KPA Radiator Coolant Expansion Overflow Tank Cap Cover Compatible with BMW E90 E60 F10 F01 E70 17117639021 (200bar)

As a car enthusiast and a BMW owner, I understand the importance of maintaining the integrity of my vehicle’s cooling system. One crucial component that often gets overlooked is the radiator coolant expansion overflow tank cap. That’s why I’m excited to share my analysis of the ‘200 KPA Radiator Coolant Expansion Overflow Tank Cap Cover’, which is compatible with various BMW models including the E90, E60, F10, F01, and E70. This product not only offers great functionality but also ensures that I can maintain the performance and efficiency of my engine.

The standout feature of this coolant cap is its excellent sealing capability. With a good sealing cover, I can rest assured that my coolant will remain contained within the system. This is particularly important because any coolant loss can lead to overheating, which could cause serious damage to the engine over time. By preventing coolant from leaking out, this cap helps to maintain the optimal temperature and performance of my BMW, ultimately prolonging its lifespan.

Additionally, the seamless fit of this cap is another major advantage. It has been reverse-engineered from the original equipment, which means it fits perfectly on my BMW without any hassle. I appreciate how easy it is to install and replace the old, cracked, or lost cap with this direct replacement. It’s reassuring to know that I’m not just slapping on a generic cap, but one that has been specifically designed for my vehicle model. This attention to detail ensures that I can enjoy peace of mind knowing that every part of my car is functioning as it should.

Another critical point to consider is the pressure compatibility of this coolant cap. Using caps with different pressure ratings can lead to damage, particularly to the thermostat. I find it incredibly important to confirm the size and pressure of the original cap before making a purchase, and this product clearly emphasizes that point. By ensuring I use the correct cap, I can avoid unnecessary repairs and keep my vehicle running smoothly.

the ‘200 KPA Radiator Coolant Expansion Overflow Tank Cap Cover’ is an essential purchase for any BMW owner who values performance and reliability. With its excellent sealing ability, perfect fit, and direct replacement capability, it stands out as a top choice for maintaining my cooling system. If you’re in need of a new coolant cap, I highly recommend investing in this product. It not only meets all my expectations but also gives me the confidence that I am taking the right steps to protect my vehicle. Don’t wait until you experience a coolant leak; secure your engine’s health today by choosing this reliable cap!

Feature	Description
Good Sealing	Prevents coolant from leaking, maintaining optimal engine temperature.
Seamless Fit	Reverse-engineered design for perfect compatibility with BMW models.
Direct Replacement	Replaces cracked or lost original caps easily.
Pressure Compatibility	Designed to prevent thermostat damage; confirm size and pressure before purchase.

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Why Replacing My E90 Engine Coolant Cap Made a Difference

When I first noticed my BMW E90 overheating during my daily commute, I was unsure where to start troubleshooting. After a bit of research, I discovered that a faulty engine coolant cap could be the culprit. Replacing the cap turned out to be a simple yet effective solution that helped me maintain my vehicle’s performance.

One of the primary reasons I decided to replace the coolant cap was to ensure the cooling system was functioning optimally. A worn or damaged cap can lead to coolant leaks and pressure loss, which can cause the engine to overheat. After swapping out the old cap for a new one, I noticed a significant improvement in my car’s cooling efficiency. I felt a sense of relief knowing that I was preventing potential damage to my engine, which could have resulted in costly repairs down the line.

Additionally, the replacement process was incredibly straightforward and affordable. I managed to do it myself, which not only saved me money but also gave me a sense of accomplishment. Now, I feel more confident in my ability to handle basic car maintenance, and I have peace of mind knowing that my E90 is less likely to experience cooling issues. Overall, replacing the engine coolant cap was a

Buying Guide for E90 Engine Coolant Cap Replacement

Understanding the Importance of the Coolant Cap

When I first learned about the engine coolant cap, I didn’t realize just how crucial it is for my vehicle’s cooling system. The cap maintains the pressure in the cooling system, preventing coolant from boiling over and ensuring efficient engine performance. If my cap is damaged or not functioning properly, it could lead to overheating and serious engine damage.

Identifying the Need for Replacement

I started noticing a few signs that indicated it was time to replace my coolant cap. First, I observed coolant leaks around the cap area. I also experienced fluctuating temperature readings on my dashboard, which made me concerned. If you encounter similar issues, it might be a good idea to check your coolant cap.

Researching Compatibility

Before purchasing a new coolant cap, I made sure to research compatibility with my specific E90 model. Each model may have different specifications, so I paid attention to details such as the year, make, and engine type. This step helped me avoid any mismatched parts.

Checking the Material and Quality

I learned that the material of the coolant cap can significantly impact its performance. Many caps are made from plastic or rubber. When I was looking, I focused on durability and heat resistance because the cap needs to withstand high temperatures. I also checked for reviews to gauge the quality from other users’ experiences.

Assessing Price Range

While searching for a replacement cap, I noticed a range of prices. I took my time to compare options, keeping in mind that the cheapest option may not always be the best. I considered the balance between quality and price, making sure to select a cap that fit my budget without compromising on reliability.

Understanding Installation Requirements

Installing a new coolant cap is typically a straightforward process, but I wanted to be sure I was prepared. I checked online for any specific installation instructions or tips. I found that having the right tools handy could make the process much smoother.

Buying from Reputable Sources

To avoid any issues, I chose to purchase my coolant cap from reputable sources. I looked for authorized dealers or well-reviewed online retailers. This gave me peace of mind knowing that I was getting a quality product that matched my vehicle’s requirements.

Final Checks Before Purchase

Before finalizing my purchase, I made a checklist to ensure everything was in order. I confirmed the part number, double-checked compatibility, and reviewed return policies just in case. This preparation helped me feel confident about my decision.

Replacing the engine coolant cap on my E90 was a proactive step in maintaining my vehicle. By following these guidelines, I ensured that I made an informed decision that would keep my engine running smoothly. If you’re in a similar position, I hope my experience helps guide you through the process of finding the right coolant cap replacement.

Author Profile

Tom Davis

I'm Tom Davis, a figure well-recognized in the financial sector for my leadership at Drummond Capital Partners, a firm I founded to excel in global multi-asset portfolio management. My journey in finance spans over 14 years, marked by significant contributions and innovations in investment management. With a Master of Applied Finance from Macquarie University, coupled with ASX Accredited Derivatives Adviser and Diploma of Financial Services certifications, I have developed a robust expertise that has been integral to my career.

Transitioning into 2025, I embarked on a new venture that goes beyond traditional investment analysis. Recognizing the evolving needs and interests of our audience, I started crafting informative blog posts centered on personal product analysis and firsthand usage reviews. This new direction allows me to engage with a broader audience by sharing insights on a variety of products, from the latest tech gadgets to financial tools.

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