MMX
MMX BMW & MINI 90mm Billet Coolant Expansion Tank Cap
BACKORDER - AVAILABLE
Pay later options
Spread the cost of your order. Choose your provider at checkout — nothing to set up here.
KLARNA FINANCE
Part 1: How it works
Shop now. Pay later with Klarna.
Please spend responsibly. Borrowing more than you can afford could seriously affect your financial status. Make sure you can afford to make your monthly repayments on time.
Step 1: Add products to your cart and select “Klarna” when you check out
Step 2: Enter a few personal details and you’ll know instantly if you’re approved
Step 3: Klarna will send you an email confirmation and reminders when it’s time to pay and you can manage your orders and payments in the Klarna app.
Part 2: Payments information
Pay in 30 days
Make your purchase today so you can try before you buy. Only pay for what you keep. Pay up to 30 days later. No interest. No fees. No impact to your credit score.
Paying after delivery allows you to try before you buy and is the easiest way to shop online.
- Complete the payment in full after purchase at no added cost.
- Report returns directly in our app and only pay for the items that you keep.
- Not making your payment on time could affect your ability to use Klarna in the future.
- Debt collection agencies are used as a last resort
You must be 18+ and a UK resident to be eligible for this credit offer. Pay Later Terms and Conditions
Pay in 3 interest-free instalments
Spread the cost of your purchase into 3 interest-free instalments. The first payment is made at point of purchase, with remaining instalments scheduled automatically every 30 days. No interest or fees. Select the Klarna option and enter your debit or credit card information. To check your eligibility, Klarna will perform a soft search with a credit reference agency. This will not affect your credit score.
No interest. No fees. No impact to your credit score.
- A new way to pay that's an alternative to a credit card.
- 3 instalments gives you flexibility to shop without interest or hidden fees. - Not making your payment on time could affect your ability to use Klarna in the future.
- Debt collection agencies are used as a last resort.
You must be 18+ and a UK resident to be eligible for this credit offer. Pay in 3 Terms and Conditions
Part 3: About Klarna
Pay online or in the app
Review your latest purchases and make payments in the Klarna app or online.
● Download the Klarna app: https://www.klarna.com/app
● Log in online: https://app.klarna.com/login
● Chat with customer service: https://www.klarna.com/uk/customer-service/
Safe and secure
With Klarna, you are always covered through Klarna’s Buyer Protection policy. Modern safeguards protect your information to prevent unauthorized purchases.Frequently asked questions
Visit our FAQ (https://www.klarna.com/uk/customer-service/) page to find out more about using Klarna.About Klarna
At Klarna, we have a relentless focus on creating the best shopping experience in the world. We believe payments are so much more than just a way to send money. That’s why our smooth checkout options give you more time and control so you can focus on the things you love.● More than 90 million shoppers are using Klarna.
● 200,000 retailers are working with us worldwide.
● We’re one Europe’s largest banks and we’ve been powering online checkouts for over 15 years.
Please spend responsibly. Borrowing more than you can afford could seriously affect your financial status. Make sure you can afford to make your monthly repayments on time.
R44 Performance Ltd. is not a lender and acts only as an introducer. The credit product is provided by Klarna Bank AB (publ). Credit is only available to permanent UK residents aged 18 and over, depending on their status. Terms and conditions apply. Please note that Pay in 30 days and Pay in 3 instalments are not regulated by the FCA.
Choose options
BACKORDER - AVAILABLE
Pay later options
Spread the cost of your order. Choose your provider at checkout — nothing to set up here.
KLARNA FINANCE
Part 1: How it works
Shop now. Pay later with Klarna.
Please spend responsibly. Borrowing more than you can afford could seriously affect your financial status. Make sure you can afford to make your monthly repayments on time.
Step 1: Add products to your cart and select “Klarna” when you check out
Step 2: Enter a few personal details and you’ll know instantly if you’re approved
Step 3: Klarna will send you an email confirmation and reminders when it’s time to pay and you can manage your orders and payments in the Klarna app.
Part 2: Payments information
Pay in 30 days
Make your purchase today so you can try before you buy. Only pay for what you keep. Pay up to 30 days later. No interest. No fees. No impact to your credit score.
Paying after delivery allows you to try before you buy and is the easiest way to shop online.
- Complete the payment in full after purchase at no added cost.
- Report returns directly in our app and only pay for the items that you keep.
- Not making your payment on time could affect your ability to use Klarna in the future.
- Debt collection agencies are used as a last resort
You must be 18+ and a UK resident to be eligible for this credit offer. Pay Later Terms and Conditions
Pay in 3 interest-free instalments
Spread the cost of your purchase into 3 interest-free instalments. The first payment is made at point of purchase, with remaining instalments scheduled automatically every 30 days. No interest or fees. Select the Klarna option and enter your debit or credit card information. To check your eligibility, Klarna will perform a soft search with a credit reference agency. This will not affect your credit score.
No interest. No fees. No impact to your credit score.
- A new way to pay that's an alternative to a credit card.
- 3 instalments gives you flexibility to shop without interest or hidden fees. - Not making your payment on time could affect your ability to use Klarna in the future.
- Debt collection agencies are used as a last resort.
You must be 18+ and a UK resident to be eligible for this credit offer. Pay in 3 Terms and Conditions
Part 3: About Klarna
Pay online or in the app
Review your latest purchases and make payments in the Klarna app or online.
● Download the Klarna app: https://www.klarna.com/app
● Log in online: https://app.klarna.com/login
● Chat with customer service: https://www.klarna.com/uk/customer-service/
Safe and secure
With Klarna, you are always covered through Klarna’s Buyer Protection policy. Modern safeguards protect your information to prevent unauthorized purchases.Frequently asked questions
Visit our FAQ (https://www.klarna.com/uk/customer-service/) page to find out more about using Klarna.About Klarna
At Klarna, we have a relentless focus on creating the best shopping experience in the world. We believe payments are so much more than just a way to send money. That’s why our smooth checkout options give you more time and control so you can focus on the things you love.● More than 90 million shoppers are using Klarna.
● 200,000 retailers are working with us worldwide.
● We’re one Europe’s largest banks and we’ve been powering online checkouts for over 15 years.
Please spend responsibly. Borrowing more than you can afford could seriously affect your financial status. Make sure you can afford to make your monthly repayments on time.
R44 Performance Ltd. is not a lender and acts only as an introducer. The credit product is provided by Klarna Bank AB (publ). Credit is only available to permanent UK residents aged 18 and over, depending on their status. Terms and conditions apply. Please note that Pay in 30 days and Pay in 3 instalments are not regulated by the FCA.
BACKORDER - AVAILABLE
Pay later options
Spread the cost of your order. Choose your provider at checkout — nothing to set up here.
KLARNA FINANCE
Part 1: How it works
Shop now. Pay later with Klarna.
Please spend responsibly. Borrowing more than you can afford could seriously affect your financial status. Make sure you can afford to make your monthly repayments on time.
Step 1: Add products to your cart and select “Klarna” when you check out
Step 2: Enter a few personal details and you’ll know instantly if you’re approved
Step 3: Klarna will send you an email confirmation and reminders when it’s time to pay and you can manage your orders and payments in the Klarna app.
Part 2: Payments information
Pay in 30 days
Make your purchase today so you can try before you buy. Only pay for what you keep. Pay up to 30 days later. No interest. No fees. No impact to your credit score.
Paying after delivery allows you to try before you buy and is the easiest way to shop online.
- Complete the payment in full after purchase at no added cost.
- Report returns directly in our app and only pay for the items that you keep.
- Not making your payment on time could affect your ability to use Klarna in the future.
- Debt collection agencies are used as a last resort
You must be 18+ and a UK resident to be eligible for this credit offer. Pay Later Terms and Conditions
Pay in 3 interest-free instalments
Spread the cost of your purchase into 3 interest-free instalments. The first payment is made at point of purchase, with remaining instalments scheduled automatically every 30 days. No interest or fees. Select the Klarna option and enter your debit or credit card information. To check your eligibility, Klarna will perform a soft search with a credit reference agency. This will not affect your credit score.
No interest. No fees. No impact to your credit score.
- A new way to pay that's an alternative to a credit card.
- 3 instalments gives you flexibility to shop without interest or hidden fees. - Not making your payment on time could affect your ability to use Klarna in the future.
- Debt collection agencies are used as a last resort.
You must be 18+ and a UK resident to be eligible for this credit offer. Pay in 3 Terms and Conditions
Part 3: About Klarna
Pay online or in the app
Review your latest purchases and make payments in the Klarna app or online.
● Download the Klarna app: https://www.klarna.com/app
● Log in online: https://app.klarna.com/login
● Chat with customer service: https://www.klarna.com/uk/customer-service/
Safe and secure
With Klarna, you are always covered through Klarna’s Buyer Protection policy. Modern safeguards protect your information to prevent unauthorized purchases.Frequently asked questions
Visit our FAQ (https://www.klarna.com/uk/customer-service/) page to find out more about using Klarna.About Klarna
At Klarna, we have a relentless focus on creating the best shopping experience in the world. We believe payments are so much more than just a way to send money. That’s why our smooth checkout options give you more time and control so you can focus on the things you love.● More than 90 million shoppers are using Klarna.
● 200,000 retailers are working with us worldwide.
● We’re one Europe’s largest banks and we’ve been powering online checkouts for over 15 years.
Please spend responsibly. Borrowing more than you can afford could seriously affect your financial status. Make sure you can afford to make your monthly repayments on time.
R44 Performance Ltd. is not a lender and acts only as an introducer. The credit product is provided by Klarna Bank AB (publ). Credit is only available to permanent UK residents aged 18 and over, depending on their status. Terms and conditions apply. Please note that Pay in 30 days and Pay in 3 instalments are not regulated by the FCA.
The MMX 90mm Billet Coolant Expansion Cap is the larger of the two MMX coolant cap sizes, designed in the UK and machined from a solid billet of aluminium. It is a direct replacement for BMW and MINI models running OE part number 17 11 7 639 021, and takes the place of the factory cap rather than sitting over it.
Match The Cap Diameter, Not The Model
BMW fits both a 60mm and a 90mm expansion tank cap across its range, and the two are not interchangeable. Reading the number moulded into the existing cap is the only reliable check. This MMX cap covers OE 17 11 7 639 021; the smaller 60mm fitment is available as a separate MMX part.
Pressure Retained, Finish Improved
The expansion tank cap holds the cooling system at its designed pressure, so it has a job to do beyond appearance. Rather than a cover, MMX machines a full replacement that seals correctly while removing the discoloured plastic item that stands out in an otherwise finished engine bay.
Key Features
- CNC-machined in the UK from solid billet aluminium
- Direct replacement for OE part number 17 11 7 639 021
- 90mm expansion tank fitment
- Not an adhesive cover – the factory cap is replaced outright
- Anodised finish for lasting corrosion resistance
- Fully reversible – the OEM cap can be refitted at any time
Specifications
- Part Number: MMR03-1502
- Replaces OE: 17 11 7 639 021
- Diameter: 90mm
- Material: Billet aluminium, anodised
Compatibility
- BMW and MINI models fitted with the 90mm expansion tank cap, OE 17 11 7 639 021
- Always confirm the part number on the existing cap before ordering
Frequently Asked Questions
How is 90mm confirmed against 60mm?
Read the part number on the factory cap. 17 11 7 639 021 is the 90mm cap; 17 11 7 639 024 is the 60mm version, for which MMX offers a separate part.
Can the cap be fitted with the engine hot?
No. A cooling system should only be opened when fully cold, exactly as with the factory cap.
Why Choose An MMX Billet Cap?
A billet coolant cap is a small change that lifts the whole engine bay, and MMX builds it as a working pressure component rather than a decorative shell. R44 Performance stocks the complete MMX under-bonnet range.
Unless explicitly stated otherwise, all products sold by R44 Performance Limited are designated RACE ONLY and are solely for competition or off-road use limited to racing formally sanctioned by a recognized racing organization. Any other use, including recreational off-road use, may violate local, state, and Federal laws. R44 Performance Limited does not implicitly or explicitly confirm the legality of using any products it sells on public roads; that is entirely the responsibility of the consumer.
It is the responsibility of the customer to check with all federal, state local and environmental laws before ordering and installing a product. R44 Performance Limited is not responsible for any fees, fines or costs that a customer may incur as a result of failing to check with federal, state, local or environmental laws before ordering and installing a product.
We get a large number of custom orders and requests everyday, so as a result it is not always possible for us to keep every item in stock at all times in our warehouse. If you require the item urgently please contact our sales team here to check the stock before you make your purchase.
We totally understand if you're not certain a part will be compatible with your car, so we highly recommend contacting us here with your query. Our friendly sales team will then be in touch to confirm if this part is the correct part you are looking for.
All in stock products ship the same day if ordered before 2pm GMT
For out of stock items we will contact you with an estimated wait time if not otherwise specified above.
We offer worldwide shipping on all products. If upon receiving your product you wish to return; we offer a 30-day returns policy. For our in-depth returns information please follow the link. "R44 Returns Policy
All of our products come with a standard warranty of 1-3 years. This is dependant on the type of product however. For more details please see our warranty page here.
PLEASE NOTE
- Orders with both in-stock and backorder or out-of-stock products will be dispatched once all products are available to ship together.
- Contact our sales team if you want your parts fitted to your vehicle at our London workshop.
- Shipping estimates are based on courier delivery times and don't include time to despatch from our warehouse.