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BMW Cooling System Parts & Accessories for BMW X Series F39 (2018+)

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The cooling system is arguably the weakest point in numerous BMWs. If you drive an aging BMW or plan on taking your car to the track like we do, we recommend beefing up your cooling system before going to the track. Generally, the main components in your cooling system that are prone to failure include the following: expansion tank, factory hoses, water pump, thermostat, fan (especially if your vehicle comes factory with a clutch fan), and radiator. Factory BMW expansion tanks are plastic and prone to either breaking off at connection points or combusting. As factory rubber hoses age they either crack or break over time - we offer silicone cooling hose upgrades for most applications to avoid future failures. If you have an older vehicle, your water pump likely comes from the factory with a plastic impeller - we offer upgraded water pumps with metal impellers that are far more reliable. Newer model BMWs utilize electric water pumps - BMW spent millions of dollars engineering these water pumps, but they fail so often that we recommend replacing at 60,000 mile service intervals to avoid being stranded on the side of the road. In terms of thermostats, we offer various upgraded thermostats for racing applications. If your BMW utilizes a clutch fan from the factory, we have several options available in terms of universal electric fans - we recommend replacing these to avoid sending brittle plastic fan blades through your hood. For radiators, we recommend swapping out your radiator for one that does not use plastic connection points like your factory radiator.

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OEM Rein Aluminum Coolant Flange Connector - BMW & MINI B36 B46/B48 G...

For vehicles with the earlier Gen1 B46/B48 engine - Not compatible with the later TU en...

2X Entries For Our G87 M2 Sweepstakes! We Price Match - Give Us A Call or Chat!

T#:33679696

Part#: 11118511205

In Stock

$ 50.99 USD

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$ 50.99 USD

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Plastic coolant flanges become brittle over time, which can cause them to crack and fail. Prevent overheating and coolant loss with this OEM Rein upgraded aluminum coolant flange.

Silver Auxiliary Coolant Reservoir Cap

T#:38128032

Part#: 201-0394-SIL

Ships in 8 Business Days

$ 99.99

This product was last offered at the strikethrough price on
01-22-2026

$ 94.99 USD

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$ 94.99 USD

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BMW Silver Auxiliary Coolant Reservoir Cap is the perfect upgrade for BMW owners looking to enhance both the aesthetics and functionality of their engine bay. Unlike generic aftermarket caps that overlook critical pressure regulation, this precision-engineered cap retains the OEM pressure release functionality, ensuring safe and reliable coolant system performance.

Crafted from high-quality billet aluminum, this reservoir cap offers superior durability and resistance to heat and fluids, preventing warping or degradation over time. Unlike adhesive-based cap covers that can loosen or fall off, this cap is a direct replacement for the factory component, providing a secure, high-performance solution.

OEM pressure release functionality – Maintains proper system regulation for optimal coolant performance
Premium billet aluminum construction – Offers enhanced durability and longevity
Direct replacement design – Secure fit without adhesives or modifications
Resistant to heat and fluids – Ensures long-lasting reliability in extreme conditions
Performance-inspired look – Adds a sleek, high-end appearance to your engine bay
Upgraded durability – Prevents cracking, leaks, and premature wear

Upgrade your BMW’s cooling system with the BMW Silver Auxiliary Coolant Reservoir Cap, blending performance, reliability, and premium styling.

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OEM Rein Turbocharger Coolant Supply Line - BMW Gen2 B46/B48 2.0L ...

2X Entries For Our G87 M2 Sweepstakes! We Price Match - Give Us A Call or Chat!

T#:34315143

Part#: 11538629971

Ships in 4 Business Days

$ 47.99

This product was last offered at the strikethrough price on
04-28-2026

$ 42.99 USD

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$ 42.99 USD

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Turbo coolant supply lines feed coolant to the turbocharger, ensuring temperatures are kept in check. If your coolant line is leaking, it is important to replace it as soon as possible to prevent coolant loss, overheating, and turbo damage.

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OEM Rein Engine Coolant Hose - Turbo Charger - BMW F48 F39 B46/B48 ...

2X Entries For Our G87 M2 Sweepstakes!

T#:40985138

Part#: 17127617377

In Stock

$ 70.99

This product was last offered at the strikethrough price on
05-03-2026

$ 59.99 USD

Limited Qty Sale

Add to Wish List

Qty

$ 70.99

This product was last offered at the strikethrough price on
05-03-2026

$ 59.99 USD

Limited Qty Sale

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This OEM Rein coolant hose connects the auxiliary pump to the heat exchanger hose. Replace your old, cracked coolant hose with this new hose from Rein to prevent coolant loss and overheating.

Upper Coolant Hose

2X Entries For Our G87 M2 Sweepstakes! We Price Match - Give Us A Call or Chat!

T#:38195380

Part#: 17127617363

In Stock

$ 73.99 USD

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Qty

$ 73.99 USD

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Hose From Radiator Bottom - Thermostat CHR0800

2X Entries For Our G87 M2 Sweepstakes! We Price Match - Give Us A Call or Chat!

T#:38195379

Part#: 17127617368

In Stock

$ 45.99 USD

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Qty

$ 45.99 USD

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OEM Rein Turbocharger Coolant Return Line - BMW & MINI B36 B46/B48 ...

T#:45757431

Part#: 11539488188

Ships in 4 Business Days

$ 55.99 USD

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Qty

$ 55.99 USD

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The coolant return hose is responsible for taking cooling from the turbocharger and returning it back to the engine coolant system, allowing a free flow of coolant to keep the turbocharger temperatures under control.

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BMW Black Auxiliary Coolant Reservoir Cap

T#:38128031

Part#: 201-0394-BLK

Ships in 10 Business Days

$ 99.99

This product was last offered at the strikethrough price on
01-22-2026

$ 94.99 USD

Add to Wish List

Qty

$ 94.99 USD

Add to Wish List

BMW Black Auxiliary Coolant Reservoir Cap is the perfect upgrade for BMW owners looking to enhance both the aesthetics and functionality of their engine bay. Unlike generic aftermarket caps that overlook critical pressure regulation, this precision-engineered cap retains the OEM pressure release functionality, ensuring safe and reliable coolant system performance.

Crafted from high-quality billet aluminum, this reservoir cap offers superior durability and resistance to heat and fluids, preventing warping or degradation over time. Unlike adhesive-based cap covers that can loosen or fall off, this cap is a direct replacement for the factory component, providing a secure, high-performance solution.

OEM pressure release functionality – Maintains proper system regulation for optimal coolant performance
Premium billet aluminum construction – Offers enhanced durability and longevity
Direct replacement design – Secure fit without adhesives or modifications
Resistant to heat and fluids – Ensures long-lasting reliability in extreme conditions
Performance-inspired look – Adds a sleek, high-end appearance to your engine bay
Upgraded durability – Prevents cracking, leaks, and premature wear

Upgrade your BMW’s cooling system with the BMW Black Auxiliary Coolant Reservoir Cap, blending performance, reliability, and premium styling.

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BMW Blue Auxiliary Coolant Reservoir Cap

T#:38128029

Part#: 201-0394-BLU

Ships in 10 Business Days

$ 99.99

This product was last offered at the strikethrough price on
01-22-2026

$ 94.99 USD

Add to Wish List

Qty

$ 94.99 USD

Add to Wish List

BMW Blue Auxiliary Coolant Reservoir Cap is the perfect upgrade for BMW owners looking to enhance both the aesthetics and functionality of their engine bay. Unlike generic aftermarket caps that overlook critical pressure regulation, this precision-engineered cap retains the OEM pressure release functionality, ensuring safe and reliable coolant system performance.

Crafted from high-quality billet aluminum, this reservoir cap offers superior durability and resistance to heat and fluids, preventing warping or degradation over time. Unlike adhesive-based cap covers that can loosen or fall off, this cap is a direct replacement for the factory component, providing a secure, high-performance solution.

OEM pressure release functionality – Maintains proper system regulation for optimal coolant performance
Premium billet aluminum construction – Offers enhanced durability and longevity
Direct replacement design – Secure fit without adhesives or modifications
Resistant to heat and fluids – Ensures long-lasting reliability in extreme conditions
Performance-inspired look – Adds a sleek, high-end appearance to your engine bay
Upgraded durability – Prevents cracking, leaks, and premature wear

Upgrade your BMW’s cooling system with the BMW Blue Auxiliary Coolant Reservoir Cap, blending performance, reliability, and premium styling.

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- Coolant Hoses & Pipes (6)
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