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

As a car enthusiast and a proud owner of a BMW E90, I’ve come to appreciate the intricate dance of engineering that keeps our vehicles running smoothly. One of the unsung heroes in this finely-tuned machinery is the engine coolant cap—a seemingly simple component that plays a crucial role in maintaining optimal engine temperatures. Over time, however, wear and tear can take their toll, leading to leaks or pressure issues that could spell trouble for our beloved rides. In this article, I’ll share my insights and experiences on the importance of replacing the E90 engine coolant cap, ensuring that our engines remain in peak condition. Whether you’re a seasoned DIY mechanic or a curious newcomer, understanding this essential maintenance task can help you keep your BMW performing at its best and extend its lifespan on the road. Join me as we delve into the world of coolant caps and discover why a small replacement can make a big difference.

I Replaced The E90 Engine Coolant Cap And Share 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

As a car enthusiast and an owner of a BMW, I understand the importance of maintaining our vehicles in optimal condition. That’s why I was particularly impressed when I came across the 17117639020 Radiator Coolant Reservoir Tank Cap. This product is designed specifically for various BMW models, including the E70, E82, E88, E89, E90, E92, F01, F04, F06, F07, F15, F16, F26, F32, F33, and F87. With its maximum pressure of 140KPa, it promises to enhance the performance of your vehicle’s cooling system significantly. Let’s dive into the features and why I believe this coolant cap is an essential upgrade for any BMW owner.

First and foremost, the excellent quality of this coolant cap cannot be overstated. Made from high-quality ABS plastic and sealing rubber, it is designed to withstand both extreme cold and heat. This durability is crucial for car parts that face such harsh conditions regularly. I appreciate that the manufacturer has improved the pressure relief function, ensuring that the cap maintains the necessary pressure without risking leaks. The high-quality sealing rubber gaskets provide a tight seal, which means that I can trust this product to keep the radiator tank closed and prevent any leakage. This quality assurance is something I always look for in automotive parts.

Another key feature is its compatibility with a wide range of BMW models, particularly those manufactured between 2006 and 2015. As someone who values precision and fit, I find it reassuring that the product description encourages potential buyers to confirm compatibility before purchase. This level of attention to detail is critical; after all, an improperly fitting cap could lead to significant issues. It’s worth taking a moment to check if your BMW is on the compatibility list, as this part can fit numerous popular models.

The product also lists specific replacement numbers, making it easier to verify that I am purchasing the correct cap. This feature is particularly helpful for those who may not be familiar with automotive parts and references. The reference part numbers include 17-11-7-639-020, 17117639020, 17117521071, and others, ensuring that I can quickly and accurately identify the right part for my vehicle. This transparency is a big plus in my book, as it reduces the chances of making an incorrect purchase.

It’s also important to note the safety precautions provided in the product description. The reminder to allow the engine to cool down before removing the coolant overflow cap is a crucial safety tip that can prevent severe burns from hot coolant. This level of consideration for user safety shows that the manufacturer cares about their customers and is committed to providing a safe experience while using their products.

Finally, I was pleased to see that the product comes with an after-sale service commitment. The mention of strict quality control standards reassures me that the manufacturer stands behind their product. In my experience, having reliable customer service can make all the difference when dealing with automotive parts, as issues can sometimes arise after installation.

Feature	Description
Quality	High-quality ABS plastic and sealing rubber, resistant to cold and heat.
Pressure Relief	Enhanced pressure relief function with a maximum pressure of 140KPa.
Compatibility	Fits a wide range of BMW models from 2006 to 2015.
Replacement Numbers	Includes multiple part numbers for easy verification.
Safety Precautions	Important tips to prevent burns when removing the cap.
After-Sale Service	Strict quality control and customer service commitment.

the 17117639020 Radiator Coolant Reservoir Tank Cap is not just another car accessory; it’s a vital component that ensures the longevity and efficiency of my BMW’s cooling system. With its excellent quality, compatibility, and safety features, I feel confident that this product will serve me well. If you’re a BMW owner, I highly recommend considering this coolant cap for your vehicle. It’s a small investment that can lead to significant benefits in terms of performance and peace of mind. Don’t hesitate to make this upgrade; your car will thank you!

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

2. 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 a BMW owner, I understand the importance of maintaining the integrity and performance of my vehicle. That’s why I am excited to talk about the ComfyBuy Expansion Tank Cap 17117521071. This product is not just a simple cap; it’s a crucial component that ensures the proper functioning of the coolant system in various BMW models. If you’re a BMW owner like me, you know that even the smallest details matter when it comes to performance and reliability.

One of the standout features of this expansion tank cap is its OEM-quality engineering. It is precisely designed to meet or even exceed OEM specifications. This means that it fits perfectly and creates a secure, leak-free seal for your BMW’s coolant reservoir. I can’t stress enough how vital it is to have a reliable cap; a poorly fitting cap can lead to coolant leaks, which can cause significant damage to your engine over time. Knowing that this cap is designed to keep my coolant system sealed gives me peace of mind.

Moreover, the ComfyBuy Expansion Tank Cap is compatible with a wide range of BMW models, including the 3 Series (E46), 5 Series (E39, E60), X3 (E83), X5 (E53), Z4 (E85, E86), and more. This versatility is a huge plus for BMW owners, as it eliminates the hassle of searching for specific parts for different models. It’s essential to check your vehicle’s part number for fitment, but the broad compatibility means that many owners can benefit from this product.

Durability is another significant aspect of this expansion tank cap. Made from high-quality reinforced plastic, it is designed to withstand extreme temperatures and the pressure of the coolant system. I’ve had my fair share of caps cracking or leaking due to heat exposure, and it’s always a frustrating experience. With this cap, I can trust that it will hold up under pressure, preventing any unwanted leaks that could lead to overheating and costly repairs.

Additionally, this cap plays a critical role in maintaining proper pressure within the cooling system. By preventing coolant evaporation and potential engine overheating, it helps to keep my engine running smoothly and efficiently. As someone who values performance, having a reliable cap that contributes to the overall health of my engine is a must.

Installation is straightforward and user-friendly. I appreciate products that save me time and effort, and this expansion tank cap is no exception. It offers a hassle-free installation process; all I need to do is remove the old cap and replace it with this high-quality alternative without any modifications. This ease of use is particularly beneficial for those of us who prefer to handle maintenance tasks ourselves.

Feature	Description
OEM Quality	Meets or exceeds OEM specifications for secure, leak-free seal.
Compatibility	Fits multiple BMW models; check part number for fitment.
Durability	Reinforced plastic construction withstands high temperatures and pressure.
Prevention	Maintains proper pressure, preventing coolant evaporation and overheating.
Easy Installation	Direct replacement; no modifications needed for installation.

the ComfyBuy Expansion Tank Cap 17117521071 is an excellent investment for any BMW owner looking to maintain their vehicle’s performance and reliability. With its OEM-quality construction, compatibility with multiple models, durable materials, and ease of installation, this cap is a practical choice that can prevent costly engine issues down the line. I highly recommend considering this product if you’re in need of a replacement cap. It’s a small investment that can make a significant difference in the longevity and efficiency of your BMW’s coolant system. Don’t wait until it’s too late—upgrade your expansion tank cap today!

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

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

When I first came across the ‘Radiator Expansion Tank Cap 140 KPa’, I immediately recognized its importance for BMW owners. This product is not just another car accessory; it’s a crucial component that ensures the proper functioning of your vehicle’s cooling system. If you own a BMW model ranging from the E82 to the F16 series, this radiator cap is designed specifically for you, offering a perfect fit that guarantees optimal performance. Replacing part numbers such as 17117639020 and 17117521071, I found this cap to be a reliable solution for maintaining the integrity of my car’s coolant system.

The compatibility of this expansion tank cap is impressive. It supports various engine types, including N54B30A and N52B30A, making it a versatile choice for a wide range of BMW models. I appreciate that it fits cars from the 1, 2, 3, 4, 5, 6, 7, X, and Z series, which means that many BMW enthusiasts like myself can benefit from this product. The detail provided about compatibility with specific models, such as the 328i, 330i, and various X1 models, gives me confidence in its applicability. Ensuring that I select the right part for my vehicle is crucial, and the clear information allows me to do just that.

One of the standout features of this radiator expansion tank cap is its high quality. Constructed from durable materials, it promises reliability and longevity, which is essential when considering the stresses placed on a vehicle’s cooling system. I find it reassuring that the cap is designed for easy installation, as I prefer to handle minor repairs myself when possible. The direct replacement nature of this product means that I won’t have to worry about complex modifications or additional parts, simplifying the repair process.

Furthermore, the customer service aspect of this product is commendable. The assurance that the company is committed to keeping customers satisfied is a significant factor for me when making a purchase. Knowing that I can reach out for assistance if I encounter any issues gives me peace of mind. Additionally, the note advising that the cap must be fitted and sealed properly to avoid leaks is a thoughtful reminder, as it emphasizes the importance of installation integrity.

I believe that the ‘Radiator Expansion Tank Cap 140 KPa’ is an excellent investment for any BMW owner. With its perfect fit, compatibility across multiple models, and high-quality construction, it addresses a vital need in vehicle maintenance. The ease of installation and commitment to customer satisfaction further solidify my belief that this product is worth purchasing. If you’re looking to maintain your BMW’s performance and prevent potential overheating issues, I wholeheartedly recommend you consider this radiator cap. It’s a small investment that can have a significant impact on your vehicle’s longevity and reliability.

Feature	Description
Perfect Fit	Replaces OEM part numbers 17117639020, 17117521071
Compatibility	Compatible with various BMW models, including 1, 2, 3, 4, 5, 6, 7, X, Z series
High Quality	Durable material for reliability and longevity
Easy Installation	Direct replacement with no complex modifications required
Customer Service	Commitment to customer satisfaction with support available

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

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 someone who values the importance of maintaining my vehicle, I found the 200 KPA Radiator Coolant Expansion Overflow Tank Cap Cover particularly noteworthy. This product is designed specifically for BMW models like the E90, E60, F10, F01, and E70, making it a perfect fit for those who own these vehicles. The model number, 17117639021, is crucial for ensuring compatibility, and I appreciate that the manufacturer has taken the time to focus on providing a product that meets the original specifications. The quality of this cap could be a game-changer for anyone seeking to enhance their car’s performance and longevity.

One of the standout features of this radiator cap is its excellent sealing capability. This means that it prevents coolant from leaking out, which is vital for maintaining the correct operating temperature of your engine. A good sealing cover can significantly reduce the risk of overheating, which can lead to costly repairs down the road. For someone like me, who values reliability in a vehicle, this feature alone makes the cap worth considering. I know that I can drive with peace of mind, knowing my coolant system is secure.

Additionally, this cap is engineered to fit seamlessly, as it has been reverse-engineered from the original equipment. This attention to detail ensures that the cap fits perfectly, without any gaps or issues that could lead to leaks. As a car owner, I’ve experienced the frustration of ill-fitting parts, and I appreciate that this product promises a direct replacement for any cracked or lost original cap. This eliminates the guesswork involved in finding the right part and gives me confidence that I’m making a smart choice.

Another critical point to note is that using caps with different pressure ratings can damage the thermostat, which is a vital component of the cooling system. The 200 KPA rating is specifically designed to match the original specifications, so I know I am getting a product that works in harmony with the rest of my car’s cooling system. It emphasizes the importance of double-checking the size and pressure of the original cap before making a purchase, which is a wise reminder to all BMW owners. It’s a simple step that can save a lot of hassle later on.

Overall, I feel that the 200 KPA Radiator Coolant Expansion Overflow Tank Cap Cover is an excellent investment for BMW owners. The combination of good sealing, a seamless fit, and the assurance of direct replacement makes it a product that not only enhances my vehicle’s performance but also gives me peace of mind. If you are looking for a reliable and high-quality cap that will serve its purpose effectively, I strongly recommend considering this one. It’s not just a purchase; it’s a step towards ensuring the longevity and efficiency of your engine.

Feature	Description
Sealing Capability	Excellent sealing to prevent coolant leakage.
Seamless Fit	Reverse-engineered for a perfect fit with no gaps.
Direct Replacement	Replaces cracked or lost original caps easily.
Pressure Rating	200 KPA, ensuring compatibility with the cooling system.
Compatibility	Designed for BMW E90, E60, F10, F01, and E70 models.

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 that my BMW E90 was experiencing fluctuating temperature readings, I didn’t think much of it. However, after doing some research, I learned that a malfunctioning coolant cap could be the culprit. Replacing the coolant cap turned out to be a simple but effective solution that not only improved my car’s performance but also gave me peace of mind.

One of the main reasons I decided to replace the coolant cap was to maintain the proper pressure in the cooling system. A faulty cap can lead to coolant leaks and decreased pressure, which in turn can cause my engine to overheat. After installing a new cap, I noticed that the temperature gauge stabilized, and I no longer had to worry about overheating during my drives.

Additionally, I found that replacing the coolant cap is a cost-effective maintenance step. It’s a small investment compared to the potential expenses of engine damage caused by overheating or coolant leaks. Knowing that I was taking proactive measures to keep my vehicle in good condition made me feel more confident on the road. Overall, replacing the E90 engine coolant cap was a straightforward fix that significantly improved my driving experience.

E90 Engine Coolant Cap Replacement: My Buying Guide

When I first noticed issues with my E90’s engine coolant system, I realized that replacing the coolant cap was essential for maintaining optimal engine performance. Over the years, I’ve learned a few key factors to consider when it comes to choosing the right coolant cap for my vehicle. Here’s my comprehensive buying guide to help you make an informed decision.

Understanding the Importance of the Coolant Cap

I quickly discovered that the coolant cap plays a vital role in maintaining the pressure in the cooling system. A faulty cap can lead to coolant loss and overheating, which can cause severe engine damage. It’s crucial to ensure the cap is functioning properly to keep my engine running smoothly.

Checking Compatibility with My E90 Model

Before making a purchase, I always verify that the coolant cap is compatible with my specific E90 model. Different models may require different caps, so I pay close attention to the manufacturer’s specifications. This step has saved me from buying the wrong part multiple times.

Material and Build Quality

In my experience, the material and build quality of the coolant cap significantly affect its longevity. I tend to look for caps made from durable materials, as they’re less likely to warp or degrade over time. Ensuring a solid build gives me confidence that the cap will withstand high temperatures and pressure.

Pressure Rating Considerations

I learned that coolant caps come with different pressure ratings, and selecting the right one is critical. The pressure rating should match the specifications of my E90 to prevent any cooling system issues. I make sure to consult my owner’s manual or do some research to find the correct pressure rating.

Ease of Installation

One aspect I appreciate about coolant cap replacements is how straightforward the installation process is. I always look for caps that are easy to install without requiring special tools. This saves me time and hassle, allowing me to get back on the road quickly.

Price Range and Warranty

When it comes to pricing, I’ve found that coolant caps can vary significantly. I typically set a budget but also consider the value of investing in a quality part. Additionally, I always check if there’s a warranty available. A warranty provides me with peace of mind knowing that I’m covered in case of any defects.

Customer Reviews and Feedback

Reading customer reviews has been immensely helpful for me. I pay attention to feedback regarding performance and durability, as it can provide insights into how well a particular cap has worked for others. This helps me make a more informed choice based on real user experiences.

Where to Purchase

I have found that there are various places to purchase coolant caps, including local auto parts stores and online retailers. I prefer to compare prices and availability from multiple sources to ensure I’m getting the best deal. Sometimes, local stores also offer the advantage of immediate availability.

Final Thoughts

Replacing the coolant cap on my E90 has made a noticeable difference in my engine’s performance. By considering compatibility, material quality, pressure ratings, and customer feedback, I feel confident in my purchase decisions. I hope this guide helps you find the right coolant cap for your vehicle, ensuring a smooth and efficient driving experience.

Author Profile

Tonquise Frederick

My name is Tonquise Frederick, though many know me simply as TQ. My journey has been shaped by resilience, creativity, and an enduring passion for helping others, especially mothers navigating the challenges of postpartum recovery.

Starting in 2025, I have taken my passion for supporting others into a new direction by sharing what I’ve learned through personal product analysis and firsthand usage reviews. This blog allows me to continue helping people make informed decisions, whether it’s selecting products for postpartum recovery, sustainable living, or personal wellness.

Latest entries

• June 24, 2025Personal RecommendationsTransforming My Ride: Why I Switched to a 2.5-Inch to 3-Inch Exhaust Adapter and You Should Too!
• June 24, 2025Personal RecommendationsWhy I Switched to a 32 Oz Food Container: My Personal Experience and Expert Insights
• June 24, 2025Personal RecommendationsWhy Heated Ski Glove Liners Changed My Winter Adventures: An Expert’s Firsthand Experience
• June 24, 2025Personal RecommendationsHow I Improved Home Safety: My Expert Experience with Stair Tread Non Slip Solutions