Replacing My E90 Engine Coolant Cap: A Step-by-Step Guide from My Personal Experience

As a car enthusiast, I’ve always believed that the heart of any vehicle lies not just in its engine, but in the intricate systems that keep it running smoothly. One of these unsung heroes is the engine coolant cap, a seemingly simple component that plays a crucial role in maintaining optimal engine temperature. When I first encountered issues with my E90’s cooling system, I was surprised to learn how vital this little cap is for preventing leaks and ensuring proper pressure. In this article, I’ll share my journey of replacing the engine coolant cap on my E90, exploring the importance of this task and the steps I took to ensure my car remained in peak condition. Whether you’re a seasoned mechanic or a curious novice, understanding the significance of the engine coolant cap can empower you to take better care of your ride.

I Replaced The E90 Engine Coolant Cap Myself And I’m Sharing My Honest Recommendations Below

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

I am excited to share my analysis of the “Radiator Expansion Tank Cap Coolant Reservoir Cap” specifically designed for BMW 328i models from 2007 to 2016, as well as the 330i from 2016 to 2018. This product is essential for any BMW owner looking to maintain the integrity and performance of their vehicle’s cooling system. The part number, 17117639020 and 17117521071, suggests that this cap is a direct replacement for those original parts that may have become cracked or damaged over time. Ensuring that you have a reliable coolant reservoir cap is crucial for the overall health of your vehicle, and this product is an excellent choice for achieving that goal.

One of the most compelling features of this coolant reservoir cap is its compatibility with a wide range of BMW models. It fits various 1, 2, 3, and 4 Series cars, including the 128i, 135i, 228i, 320i, 328d, 328i, 330i, 335d, 335i, 428i, 430i, 435i, and 440i, among others. Furthermore, it also accommodates certain 5 and 6 Series models, as well as M and X Series vehicles. This extensive compatibility means that if you own a BMW from the specified range, you can trust this cap will fit perfectly, making it a versatile solution for many BMW drivers.

When considering the importance of a well-functioning coolant reservoir cap, it’s worth noting that a faulty cap can lead to coolant leaks, which may result in engine overheating and other serious issues. By opting for this replacement cap, I am not just ensuring that my vehicle remains in top condition, but I am also potentially saving myself from costly repairs down the line. The product guarantees a direct replacement of original broken or cracked parts, which means that I can easily install it without any additional modifications. Just make sure to fit and seal it properly to avoid any leaks.

Additionally, the package includes one coolant reservoir cap cover, making it a straightforward purchase for anyone in need of this essential component. The simplicity of the product design, combined with its effectiveness, gives me peace of mind knowing that I am investing in a high-quality part that will perform reliably.

Feature	Description
Compatibility	Fits a wide range of BMW models including 1, 2, 3, 4, 5, 6, M, and X Series.
Part Number	17117639020, 17117521071
Replacement	Direct replacement for original parts, easy installation.
Package Includes	1 PCS Coolant Reservoir Cap Cover

if you’re looking to enhance the performance of your BMW’s cooling system, I highly recommend considering the “Radiator Expansion Tank Cap Coolant Reservoir Cap.” Its broad compatibility, ease of installation, and direct replacement capabilities make it a smart choice for any BMW owner. Investing in this product not only contributes to the longevity of your vehicle but also helps ensure a smoother and more reliable driving experience. Don’t wait until a small issue becomes a big problem; make the smart decision to replace your coolant reservoir cap today!

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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 reliability of my BMW, I recognize the importance of each component, no matter how small it may seem. One such crucial part that often gets overlooked is the radiator expansion tank cap, specifically the ‘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.’ This cap serves a vital function in ensuring that my engine’s cooling system operates efficiently and effectively, making it a smart investment for any BMW owner.

The features of this coolant cap are impressive and tailored to a wide range of BMW models, including 1, 2, 3, 4, 5, 6, 7 Series, as well as various ActiveHybrid, M, X, Z, and i Series vehicles. Its compatibility with multiple models means that I can have peace of mind knowing that it is designed to fit perfectly with my car, ensuring optimal performance. The extensive list of compatible models (from 2005 to 2017) really showcases its versatility, making it suitable for many BMW enthusiasts like myself.

One of the standout aspects of this product is its excellent functionality. The cap is made from high-quality materials, which is essential for longevity and reliability. I appreciate that it has undergone rigorous testing and inspection before shipment, ensuring that it meets high standards. This level of quality control gives me confidence that I am purchasing a durable product that will stand the test of time and help prevent any coolant leaks that could lead to engine overheating.

Installation is another area where this cap shines. It’s designed as a direct replacement, which means I won’t need to struggle with complicated installations. I can easily replace my old, worn-out cap with this new one without requiring professional help, saving me time and money in the process. For someone like me who values efficiency, this feature is a significant advantage.

Furthermore, the customer service associated with this product adds an extra layer of assurance. The return policy allows me to return the cap within 30 days if I’m not satisfied, which reflects the manufacturer’s confidence in their product and gives me peace of mind when making my purchase. I believe that having such a policy is a testament to the quality and reliability of the cap.

the ‘Radiator Expansion Tank Cap, Coolant Reservoir Cap Cover’ is an excellent investment for any BMW owner looking to maintain the integrity of their vehicle’s cooling system. Its compatibility with a broad range of models, high-quality materials, easy installation, and solid customer service make it a product I would highly recommend. If you own a BMW, I genuinely believe that this cap is an essential component you shouldn’t overlook. Investing in this cap today not only protects your engine but also enhances your driving experience in the long run. Don’t wait until it’s too late—ensure your BMW runs smoothly by making this smart purchase!

Feature	Description
Compatibility	Fits multiple BMW models from 2005 to 2017 across various series.
Material Quality	Made from high-quality materials for durability and reliability.
Installation	Direct replacement for easy, hassle-free installation.
Quality Assurance	100% inspected and tested before shipment.
Customer Service	30-day return policy for unsatisfied customers.

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

As I delve into the specifics of the ‘200 KPA Radiator Coolant Expansion Overflow Tank Cap Cover’, I can’t help but appreciate the thoughtful engineering behind this product. This cap cover is designed specifically for compatibility with various BMW models, including the E90, E60, F10, F01, and E70. This means that if you own any of these vehicles, you can rest assured that this cap will fit perfectly, ensuring optimal performance and reliability. The specificity of the product is a significant plus for anyone who understands the importance of having the right components in their vehicle.

One of the standout features of this cap cover is its impressive 200 KPA (or 200 bar) rating. This high-pressure tolerance means that it can withstand intense conditions without failing. If you’re like me and enjoy driving your BMW with confidence, this cap ensures that your cooling system remains sealed and effective, even under high temperatures and pressures. This is crucial for maintaining engine health and performance, as any leak could lead to overheating, which is something every car owner dreads.

Moreover, the quality of the materials used in constructing this cap is noteworthy. A well-manufactured cap will resist wear and tear much better than cheaper alternatives. Investing in a quality cap like this one can save you from costly repairs down the line. I personally believe that spending a little more on quality can pay off immensely in the long run. It not only enhances the performance of my vehicle but also gives me peace of mind knowing that I have a reliable part installed.

Additionally, the ease of installation is a significant factor to consider. I appreciate that I can easily replace the cap without needing specialized tools or professional help. This is great news for DIY enthusiasts like me who enjoy taking care of their vehicles independently. A simple cap replacement can be an empowering task, and with this product, it’s a straightforward process that requires minimal effort.

For anyone considering this product, I believe it is a wise investment. The combination of high pressure tolerance, compatibility with popular BMW models, quality materials, and easy installation makes this cap cover a standout choice. It offers a blend of reliability and performance enhancement that is hard to beat. If you want to ensure that your BMW runs smoothly and efficiently, this cap is something I highly recommend. It’s a small part that plays a big role in your vehicle’s overall health and functionality.

Feature	Description
Pressure Rating	200 KPA (200 bar) for high-pressure tolerance
Compatibility	Fits BMW E90, E60, F10, F01, E70 models
Material Quality	Durable materials that resist wear and tear
Installation	Easy DIY installation without special tools

if you’re looking for a reliable, high-quality cap for your BMW, the ‘200 KPA Radiator Coolant Expansion Overflow Tank Cap Cover’ is an excellent choice. I truly believe that this product will enhance your vehicle’s performance and longevity, making it a smart addition to your car maintenance toolkit. Don’t hesitate—consider investing in this cap today for a better driving experience tomorrow!

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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 enthusiast and someone who values the performance and longevity of my vehicle, I recently came across the Dtomi Engine Coolant Reservoir Radiator Expansion Tank. This product is specifically designed to be compatible with a range of BMW models from 2007 to 2016, including popular series like the E90, E91, E92, and E93, as well as the X1 and Z4. Given that BMWs are known for their precision engineering and high performance, it’s critical to choose replacement parts that match these standards, and I believe this coolant reservoir does just that.

One of the standout features of the Dtomi coolant reservoir is its wide range of compatibility with various BMW models. The product boasts a comprehensive list of compatible vehicles, including the 328i, 330i, 335i, and several variants of the 1 Series and 3 Series. This extensive compatibility not only makes it a versatile choice for many BMW owners but also ensures that I can confidently recommend it to friends or family who may own different models. The replacement part numbers listed—603-334, 17137640514, 17137543026, and others—allow for easy cross-referencing, making the purchasing decision straightforward.

The quality of materials used in the construction of the Dtomi coolant reservoir is another aspect that I find impressive. Made from high-quality, durable plastic, the tank complies with OEM standards. This means that it’s built to withstand the rigors of engine heat and pressure, ensuring that it will perform reliably over time. The promise of high performance and durability gives me peace of mind, knowing that I’m investing in a product that won’t let me down when I need it the most.

Installation is often a concern for many DIY enthusiasts, and I appreciate that the Dtomi coolant reservoir is designed with ease of installation in mind. Being able to replace this part myself not only saves money on labor costs but also allows me to take pride in maintaining my vehicle. The straightforward installation process means that even those who may not be particularly mechanically inclined can handle it with a bit of guidance.

Additionally, the package includes not just the coolant reservoir but also the cap and sensor, which are essential components for ensuring the proper functioning of the cooling system. This all-in-one package is convenient and eliminates the hassle of sourcing additional parts separately.

Lastly, I want to highlight the friendly customer service that Dtomi offers. They encourage buyers to reach out if they encounter any issues with the product, which speaks volumes about their commitment to customer satisfaction. This level of support makes me feel more secure in my purchase, knowing that assistance is readily available if needed.

Feature	Description
Compatibility	Fits various BMW models (E90, E91, E92, E93, X1, Z4) from 2007-2016
Material	High-quality, durable plastic that meets OEM standards
Installation	Easy to install, suitable for DIY replacements
Included Items	Coolant Reservoir, Cap, and Sensor
Customer Service	Support available for any product-related issues

if you’re a BMW owner looking for a reliable, high-quality replacement coolant reservoir, I genuinely believe that the Dtomi Engine Coolant Reservoir Radiator Expansion Tank is a solid investment. With its compatibility, durability, ease of installation, and excellent customer service, it stands out as a smart choice. Don’t hesitate to consider this product for your vehicle; it could be the key to maintaining your BMW’s performance and extending its lifespan.

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E90 Engine Coolant Cap Replacement: A Personal Experience

When I first noticed that my E90’s engine coolant cap was worn and not sealing properly, I didn’t think much of it. However, after a few weeks of driving, I began to experience overheating issues. That’s when I realized that replacing the coolant cap could significantly improve my vehicle’s performance. A well-functioning coolant cap maintains the proper pressure in the cooling system, which is essential for preventing coolant from boiling over and ensuring that the engine operates at an optimal temperature.

After replacing the cap, I noticed an immediate improvement. The engine temperature stabilized, and I no longer had to worry about overheating during my daily commutes. It felt reassuring to know that my car was running efficiently and that I had taken a simple yet effective step toward maintaining its health. Additionally, a new coolant cap prevents coolant leaks, which not only helps with performance but also saves me from potential costly repairs down the road.

Ultimately, replacing the engine coolant cap was a small investment that yielded significant benefits. It gave me peace of mind, knowing that I was proactively maintaining my vehicle’s cooling system. If you’re experiencing similar issues or just want to ensure your E90 runs smoothly, I highly recommend considering a coolant cap replacement.

E90 Engine Coolant Cap Replacement Buying Guide

Understanding the Importance of the Coolant Cap

As I’ve come to learn, the engine coolant cap plays a crucial role in the cooling system of my E90. It helps maintain the pressure in the cooling system, preventing coolant from boiling and ensuring optimal engine temperature. If my cap is damaged or not sealing properly, it can lead to overheating and possible engine damage.

Signs That Indicate a Need for Replacement

During my time with the E90, I noticed several signs that indicated it was time to replace the coolant cap. If I see coolant leaking around the cap or notice a hissing sound when I open it, those are clear red flags. Additionally, if the dashboard warning light for overheating appears, I always check the coolant cap first.

Choosing the Right Replacement Cap

When it comes to selecting a replacement coolant cap, I prioritize compatibility with my E90 model. I always check the specifications to ensure I’m getting the right fit. I also consider the material of the cap; some are made of plastic while others may feature more durable materials. A sturdy cap gives me peace of mind.

Where to Purchase

I’ve found that I have several options for purchasing a new coolant cap. Local auto parts stores often have what I need, and I appreciate being able to inspect the product before buying. Online retailers also provide convenience and sometimes better prices, but I make sure to read reviews and confirm the part number matches my vehicle.

Installation Process

Replacing the coolant cap is straightforward, and I’ve done it myself a few times. I always begin by ensuring the engine is cool to prevent burns. After removing the old cap, I clean the area to remove any debris. Installing the new cap is as simple as twisting it on until I hear a click. It’s satisfying to know I’ve taken care of my car.

Maintenance Tips

To prolong the life of my new coolant cap, I keep an eye on the condition of the cooling system. I regularly check the coolant level and inspect the cap for any signs of wear or damage. If I notice any changes in performance or temperature, I don’t hesitate to investigate further.

In my experience, replacing the engine coolant cap on my E90 has been a manageable task that significantly contributes to the overall health of my vehicle. By understanding its importance and following the right steps for replacement, I can ensure my engine runs smoothly and efficiently.

Author Profile

Dana Weaver

Hi, I’m Dana Weaver a creative at heart with a decade-long career in content creation, branding, and visual storytelling. Back in 2019, I co-founded Ettakit, a Chicago-based digital content and branding agency built to help consumer packaged goods and wellness brands come to life through impactful visuals and strategy. That journey brought me incredible experiences from producing photo and video campaigns to crafting brand identities and web designs that told deeper stories. Along the way, I was humbled to be named in Forbes’ 30 Under 30 for Marketing & Advertising in 2022.

Starting in 2025, I began a new chapter stepping into the world of personal blogging. These days, I write hands-on reviews and informative articles about everyday products from wellness essentials and smart gadgets to home tools and parenting picks. After years of helping brands craft their voice, I wanted to use mine to bring honesty, curiosity, and clarity to the review space.

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