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

When I first encountered the need to replace the engine coolant cap on my E90, I was surprised by how often this small component can impact the overall performance of the vehicle. Many drivers overlook this seemingly minor part, but it plays a crucial role in maintaining the right pressure and temperature within the cooling system. In my journey of understanding the intricacies of automotive maintenance, I discovered that a faulty coolant cap can lead to overheating issues, coolant leaks, and even costly engine damage. In this article, I’m excited to share insights and experiences about the importance of the E90 engine coolant cap and the steps involved in replacing it. Whether you’re a seasoned DIY enthusiast or a novice looking to tackle your first car repair, you’ll find valuable information that will empower you to keep your BMW running smoothly.

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

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

As a car enthusiast and someone who values the performance of my vehicle, I was thrilled to come across the Radiator Expansion Tank Cap Coolant Reservoir Cap designed specifically for various BMW models. This product not only promises to replace the original parts seamlessly but also ensures that my car’s cooling system operates at peak efficiency. The fitment for a wide range of BMW models, including the 1, 2, 3, 4, 5, 6 series, and even M and X series, makes it an incredibly versatile option for many BMW owners like myself.

One of the standout features of this coolant reservoir cap is its compatibility with multiple BMW models, including the 128i, 328i, 330i, and even the performance-oriented M series. I can appreciate that the manufacturer has taken the time to ensure that this cap fits perfectly on these vehicles, which is crucial for avoiding any leaks or issues down the road. Having a direct replacement for broken or cracked caps means I can quickly restore my vehicle’s functionality without the hassle of searching for the right part. The part numbers 17117639020 and 17117521071 are also clearly indicated, allowing for easy identification when I need to replace it.

Moreover, the installation process appears to be straightforward. As someone who enjoys working on my car, knowing that this cap can be easily fitted and sealed onto the washer reservoir gives me peace of mind. I have had experiences in the past where aftermarket parts were difficult to install, leading to frustration and wasted time. This product promises a simple solution that I can rely on. Ensuring a secure fit is critical since any leakage could lead to cooling system failures, which no one wants to deal with, especially during the hot summer months.

Additionally, I appreciate the fact that this product comes with a single coolant reservoir cap cover, which means I am getting exactly what I need without any unnecessary extras. Sometimes, purchasing automotive parts can lead to receiving items that are not needed, which can be frustrating. The straightforward package allows for a clear understanding of what I am buying, and it aligns perfectly with my practical approach to car maintenance.

if you own a BMW from the list of compatible models, I highly recommend considering the Radiator Expansion Tank Cap Coolant Reservoir Cap. It seems to be a solid investment for maintaining the health of your vehicle’s cooling system. With its easy installation and direct replacement feature, it is designed for convenience and reliability. Don’t wait for a malfunction to occur; take control of your vehicle’s maintenance today and ensure your BMW runs smoothly for years to come. This product not only meets the needs of any BMW owner but also adds a layer of confidence in the reliability of their car’s performance.

Feature	Description
Compatibility	Fits multiple BMW models including 1, 2, 3, 4, 5, 6 series, and M & X series.
Part Numbers	17117639020, 17117521071
Replacement	Direct replacement for broken or cracked caps.
Installation	Easy to fit and seal to avoid leaks.
Package Includes	1 PCS Coolant Reservoir Cap Cover

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

2. 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

As a car enthusiast and someone who values the performance of my vehicle, I must say that the ‘17117639020 Radiator Coolant Reservoir Tank Cap’ is a remarkable product that stands out for BMW owners. This cap is designed specifically for a variety of BMW models, including the E70, E82, E88, E89, E90, E92, F01, F04, F06, F07, F15, F16, F26, F32, F33, and F87, ensuring compatibility for many drivers. If you own a BMW from 2006 to 2016, this product is definitely worth considering.

One of the most impressive features of this coolant cap is its excellent quality. The cap has an improved pressure relief function with a maximum pressure rating of 140KPa, which is crucial for maintaining the integrity of your vehicle’s cooling system. The use of high-quality ABS plastic and sealing rubber means that this cap is built to withstand extreme temperatures, both hot and cold. This durability not only ensures longevity but also provides peace of mind knowing that my vehicle’s radiator tank is securely sealed without any risk of leakage.

Compatibility is always a concern when it comes to car parts, and I appreciate that the product clearly lists all the BMW models it fits. From the 128i to the Z4, this cap replaces several OEM part numbers, including 17117521071 and 17117639020. This level of detail helps me confirm that I’m purchasing the right part for my specific vehicle, which is essential for maintaining its performance. Just a quick check before purchasing can save a lot of hassle down the line.

Another important consideration is safety, and the product comes with a vital reminder ensure the engine is cool before removing the coolant overflow cap. This precaution prevents the risk of burns from hot coolant, which is something I always keep in mind. It’s these little reminders that show the manufacturer has thought about the end-user’s safety, which I truly appreciate.

Lastly, the after-sale service offered with this product showcases the company’s commitment to quality. With strict quality control standards in place, I feel reassured that I’m investing in a product that has been thoroughly tested for performance. Knowing that support is available after my purchase adds an extra layer of confidence.

In summary, the ‘17117639020 Radiator Coolant Reservoir Tank Cap’ is a high-quality, reliable product that I believe will serve any BMW owner well. Its excellent build, compatibility, and safety features make it a smart choice for maintaining the performance of my vehicle. If you’re in the market for a new coolant cap, I highly recommend making this purchase. You won’t regret ensuring your BMW runs as smoothly as it should!

Feature	Description
Pressure Relief Function	Maximum pressure of 140KPa for optimal performance
Material	High-quality ABS plastic and sealing rubber for durability
Compatibility	Fits various BMW models from 2006 to 2016
OEM Replacement	Replaces several part numbers including 17117521071
Safety Reminder	Cool down engine before removing the cap
After-Sale Service	Strict quality control and support available

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

3. 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 BMW owner, I understand the importance of maintaining the integrity and performance of my vehicle, and that’s where the ‘Radiator Expansion Tank Cap’ comes into play. This product is specifically designed for various BMW models, including the 1, 2, 3, 4, 5, 6, 7 Series, and several others. Its compatibility with a wide range of BMW vehicles means I can trust it will fit my car perfectly, ensuring optimal performance of the cooling system. The fact that it replaces specific OEM part numbers (17117639020 and 17117521071) gives me confidence that I am choosing a reliable product that meets the original specifications.

One of the standout features of this radiator cap is its excellent compatibility with numerous BMW models. It covers a broad spectrum, from the sporty 1 Series M to the luxurious 7 Series. This extensive compatibility makes it an ideal choice for BMW enthusiasts like myself who may own multiple models or are considering purchasing a used car. Knowing that this cap can be used across various models alleviates any worries about compatibility issues.

The ‘Radiator Expansion Tank Cap’ is not just about fitting; it also boasts high-quality materials that ensure durability and reliability. The manufacturer’s commitment to quality is evident as they mention that each cap undergoes multiple inspections and tests before shipment. This attention to detail means that I can have peace of mind knowing that the product I am buying is built to last. After all, the engine coolant recovery tank cap is a crucial component in maintaining the overall health of my vehicle’s engine.

Installation is another important factor that I appreciate about this product. It’s labeled as a direct replacement with easy installation, which means I can replace my old cap without any hassle or need for professional assistance. This is particularly appealing for DIY enthusiasts like me who enjoy taking care of their cars. In just a few minutes, I can ensure that my vehicle’s cooling system operates efficiently, preventing overheating and potential engine damage.

Moreover, the manufacturer offers a 30-day return policy if I am not satisfied with the product. This customer-centric approach reassures me that they stand behind their product and value customer satisfaction. It encourages me to make the purchase without hesitation, knowing that I have the option to return it if it doesn’t meet my expectations.

Feature	Description
Compatibility	Fits BMW 1, 2, 3, 4, 5, 6, 7 Series and more.
Material Quality	Constructed from high-quality materials for durability.
Inspection Process	100% inspected and tested multiple times before shipment.
Installation	Direct replacement, easy to install.
Customer Service	30-day return policy for satisfaction guarantee.

investing in the ‘Radiator Expansion Tank Cap’ is a decision I feel good about as a BMW owner. Its compatibility, durability, ease of installation, and excellent customer service make it a smart choice for anyone looking to maintain their vehicle’s cooling system. If you’re in the market for a reliable radiator cap, I highly recommend considering this product. With its quality assurance and hassle-free return policy, it’s a purchase that comes with minimal risk and maximum benefit. Don’t wait too long; keep your BMW running smoothly and efficiently by making this purchase today!

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

When it comes to maintaining the performance and longevity of my BMW, I’ve learned that every component matters, especially the cooling system. That’s why I was excited to come across the Dtomi Engine Coolant Reservoir Radiator Expansion Tank with Cap. This product is specifically designed for a range of BMW models, including the E90, E91, E92, E93, 328i, 330i, 335i, X1, and Z4 from 2007 to 2016. If you’re a BMW owner, you know how crucial it is to ensure that your vehicle runs smoothly and efficiently. This coolant reservoir is a replacement part that can make a significant difference in your car’s performance.

The extensive compatibility of this reservoir is one of its standout features. It replaces various part numbers, including 17137607482, 17137640514, and 17137567462, which gives me confidence that it will fit my specific model. Before purchasing, it’s always wise to double-check the compatibility with your vehicle, and the clear list of compatible BMW models provided makes this process much easier. This attention to detail is particularly beneficial for someone like me who values precision in automotive parts.

Included in the package is not just the coolant reservoir tank, but also the cap and sensor. This all-in-one package is incredibly convenient. I appreciate not having to hunt for additional parts, as this ensures I have everything I need to complete the installation in one go. The high-quality, durable plastic used in the construction of the tank complies with OEM standards, which means I can trust that this product is built to last. The assurance of high performance gives me peace of mind that my BMW’s cooling system will function optimally, preventing overheating and potential engine damage.

One of the most appealing aspects of the Dtomi coolant reservoir is its ease of installation. As someone who enjoys working on my car, I find it immensely satisfying to replace parts myself. The straightforward installation process saves me both time and money compared to taking it to a mechanic. Knowing that I can handle this job on my own encourages me to take better care of my vehicle, ultimately enhancing my ownership experience. For those who may be less experienced, the friendly service offered by the manufacturer provides an extra layer of reassurance. If any issues arise, they promise to assist promptly, which is a comforting thought.

In summary, I believe the Dtomi Engine Coolant Reservoir Radiator Expansion Tank is a fantastic investment for any BMW owner looking to maintain their vehicle’s cooling system. With its compatibility, quality construction, and ease of installation, it stands out as a reliable choice. If you’re considering replacing your coolant reservoir, I highly recommend giving this product a try. Not only will it enhance your vehicle’s performance, but it will also provide you with the satisfaction of knowing you’ve made a smart choice for your car.

Feature	Description
Replacement Part Number	603-334, 17137640514, 17137543026, etc.
Compatibility	Fits various BMW models from 2007-2016
Package Includes	1 Coolant Reservoir Radiator Tank, Cap, and Sensor
Material	High-quality, durable plastic compliant with OEM standards
Installation	Easy to install, suitable for DIY
Customer Support	Friendly service with prompt assistance for issues

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

Why Replacing My E90 Engine Coolant Cap Made a Difference

When I first noticed my E90’s engine temperature gauge creeping up, I was genuinely concerned. After doing some research, I discovered that a faulty coolant cap could be the culprit. I decided to replace mine, and I’m glad I did. The engine coolant cap plays a crucial role in maintaining the system’s pressure, which is vital for preventing overheating. By replacing it, I was able to ensure that my coolant system was functioning properly, thereby protecting my engine from potential damage.

The process of replacing the coolant cap was straightforward and didn’t require any special tools. Once I installed the new cap, I immediately noticed that my engine temperature remained stable even during longer drives. This simple yet effective replacement not only gave me peace of mind but also helped improve my vehicle’s overall performance. I felt like I was taking proactive steps to extend the lifespan of my car, which is something every car owner should consider.

Additionally, keeping my E90 in optimal condition is a priority for me, and replacing the engine coolant cap was part of that routine maintenance. It’s a small investment that can save a lot of money in the long run by preventing more serious issues. Overall, I can confidently

Buying Guide for E90 Engine Coolant Cap Replacement

Understanding the Importance of the Coolant Cap

When I first learned about the E90 engine, I quickly realized that the engine coolant cap plays a crucial role in maintaining the cooling system’s pressure. A faulty cap can lead to coolant leaks and overheating, which can damage the engine over time. I knew that replacing the cap when necessary was essential for the longevity of my vehicle.

Identifying Signs of a Faulty Coolant Cap

Before I decided to replace my E90 engine coolant cap, I observed several signs that indicated it was time for a change. I noticed coolant leaks around the cap area, and sometimes the engine temperature gauge fluctuated unexpectedly. Additionally, I found that my coolant reservoir was losing fluid faster than usual. Recognizing these signs helped me make an informed decision.

Choosing the Right Replacement Cap

When I set out to find a replacement cap, I focused on compatibility with my E90 model. I made sure to check the specifications of my vehicle to ensure a proper fit. I also considered the build quality of the cap, as I wanted something that would withstand the pressure and temperature changes in the engine compartment.

Where to Purchase the Replacement Cap

I explored various purchasing options for the coolant cap. I visited local auto parts stores, where I could physically inspect the product before buying. Online retailers also offered convenience, allowing me to compare prices and read customer reviews. I found that both options had their advantages, so it ultimately depended on my preference and urgency.

Installation Process

Once I had the replacement cap in hand, I was ready to install it. The process was straightforward, and I was relieved to find that I didn’t need any special tools. I made sure the engine was cool before starting. I simply removed the old cap by twisting it counterclockwise and then installed the new cap by aligning it properly and twisting it until it clicked into place.

Testing the New Cap

After installing the new coolant cap, I took the time to test it. I started my engine and let it warm up, keeping an eye on the temperature gauge. I also inspected the area around the cap for any signs of leaks. This step gave me peace of mind, knowing that my replacement cap was functioning correctly.

Maintaining the Coolant System

Having replaced my coolant cap, I knew the importance of regular maintenance to keep my engine running smoothly. I made it a habit to check the coolant levels periodically and inspect the cap for any signs of wear or damage. By staying proactive, I felt more confident in the overall health of my E90 engine.

Replacing the E90 engine coolant cap was a rewarding experience for me. I learned a lot about my vehicle’s cooling system and how essential it is to maintain it. By following this guide, I hope others can feel empowered to tackle this task, ensuring their engines remain in top condition for years to come.

Author Profile

Sherveen Southern

My name is Sherveen Southern. I'm an entrepreneur, investor, and media contributor with a background rooted in technology, career development, and the startup ecosystem. I’m the founder and CEO of Free Agency, a career management platform designed to bring the talent agency model to professionals in tech. Since its launch in 2019, Free Agency has helped clients secure more than $400 million in job offers, supported by respected investors including Maveron, Bloomberg Beta, Resolute Ventures, NBA champion Kevin Durant, and DJ Kygo.

Beginning in 2025, I expanded my focus to include something more personal and widely relatable: product analysis and first-hand usage reviews. This blog is the result of that transition. Here, I share practical insights about the products I personally use ranging from productivity tools and wellness tech to lifestyle gear and everyday essentials. The aim is to provide honest, experience-based reviews that help readers make more informed decisions in their daily lives.

Latest entries

• April 16, 2025Personal RecommendationsWhy I Trust the Honeywell Enviracaire Elite Filter for Clean Air: My Personal Experience and Expert Insights
• April 16, 2025Personal RecommendationsWhy I Switched to an Arm Stand for My Mic: A Game-Changer for Podcasters and Streamers
• April 16, 2025Personal RecommendationsWhy Wearing an Edgar Allan Poe T-Shirt Transformed My Literary Passion: A Personal Journey
• April 16, 2025Personal RecommendationsWhy I Switched to a Gun Cabinet Pistol Rack: My Personal Experience and Expert Insights