Coolant Expansion Tank Cap, Rein - E82, F22, E9X, F3X, F10, F13, G30, F01, F02, F25, F26, G01, G02, E70, F15, G05, E71, F16, G06

This part is listed by BMW as BMW part number 17117639020 (17 11 7 639 020) and is described as Coolant Expansion Tank Cap (sometimes called the radiator cap, even though it's actually installed on the expansion tank). This cap is used on many models and chassis, such as the E90/E91/E92/E93 3 Series, E82/E88 1 Series, E84 X3, E70 X5 35d, E89 Z4, F22/F23 2 Series, F30/F31/F34 3 Series, F32/F33/F36 4 Series, F01/F02 7 Series, F10 5 Series, F12/F13 6 Series, F15 X5, F16 X6, F06 6 Series Gran Coupe, F25 X3, F26 X4, F80 M3, F82 M4, F87 M2, G01 X3, G02 X4, G05 X5, G12 7 Series (740i/Li), G30 5 Series, and more. 

While your BMW cooling system may be considered very reliable, it's all depending on this coolant reservoir cap. This cap is not just to seal the coolant expansion tank - it regulates and maintains the pressure in the cooling system (2.0 bar). A failed cap can lower the pressure inside the system and lead to an overheating situation. Replacement of the cap is recommended every three years to ensure optimum cooling efficiency and performance. It's a simple and inexpensive preventative maintenance step.

This is a radiator cap manufactured by Rein (CRP) Automotive - the original supplier to BMW for this part, as well as many other cooling system parts. As the OEM it meets all of BMW's original design, fitment, and performance requirements and is TUV approved. OEM parts are the best alternative to more expensive Original BMW parts because they are virtually identical without the inflated price tag. This part has a two year warranty.

This cap is used on many BMWs. Please make sure the style of cap matches that of your BMW, and check our detailed list of fitments below carefully.