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BMW Coolant Expansion Tanks

On certain models, namely E36, E46, and E90, the factory BMW expansion tank is prone to either breaking at connection points or blowing apart altogether. If you're starting to feel like your expansion tank is on borrowed time, it's probably time to replace with either a direct OE replacement, or strengthen your cooling setup with an aluminum expansion tank - we offer numerous performance upgrades for your expansion tank. Especially if you're someone who likes to track your BMW, we recommend upgrading your expansion tank to avoid ruining your track day.

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Coolant Expansion Tank - E46 (non-M), X3, X5 3.0

T#:338020

Part#: 17117573781

In Stock at Vendor

Sale - Save 2% $ 140.99

This product was last offered at the strikethrough price on
04-01-2026

Starting at $ 137.98 USD

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Sale - Save 2%

$ 140.99

This product was last offered at the strikethrough price on
04-01-2026

Starting at $ 137.98 USD

Add to Wish List

This coolant reservoir is for the non-M E46 3-series models from 1999-2006 (M3 takes a different expansion tank). We have found that the expansion tanks should be replaced based on age as well as condition. Expansion tanks seem to have a lifespan of less than six years before they show signs of fatigue and wear. Pre-emptively replacing the expansion tank as part of an overall maintenance plan can prevent you from getting stranded from a sudden failure later on. This is the most recent expansion tank design from Hella-Behr, the OEM supplier to BMW. It replaces the original BMW part number 17137787039.

Other items to consider replacing at the same time are the radiator cap, coolant level sensor, lower radiator hose, coolant temp sensor in the lower hose, and the hose clamps. If your car has an automatic transmission you should also replace the oil cooler thermostat in the radiator frame, which is a common source for leaks.

This coolant expansion tank fits:

1999-2006 E46 3 series - 323i, 323Ci, 325i, 325Ci, 325xi, 328i, 328Ci, 330i, 330Ci & 330xi (**no M)
2004-2008 X3 SAV - X3 2.5, X3 3.0, X3 3.0si
2000-2005 X5 SAV - X5 3.0

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OEM Coolant Expansion Tanks Kit - F22/23 F3X B48 B58

T#:27605427

Part#: 17138677649TKT

In Stock at Vendor

Sale - Save 5% $ 208.99

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

$ 198.66 USD

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Sale - Save 5%

$ 208.99

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

$ 198.66 USD

Add to Wish List

Genuine BMW expansion tanks have a bad habit of failing after a few years. This has primarily been caused by the plastic construction of the expansion tanks. After enough heat cycles, the plastic becomes brittle and can crack, causing coolant to leak out and air to enter the coolant system. If a failing expansion tank is not addressed soon enough, the coolant loss can lead to an overheating engine. This kit includes two brand new high quality expansion tanks and caps

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Cooling System Refresh Kit - Level 2 - E9x, E82, E88, Z4

T#:42099868

Part#: 11537558523TKT

Back Ordered

Sale - Save 19% $ 829.99

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

$ 671.10 USD

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Qty

Sale - Save 19%

$ 829.99

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

$ 671.10 USD

Add to Wish List

Keep your BMW running at the proper temperature and avoid costly engine repairs with the Cooling System Refresh Kit, the complete maintenance solution trusted by enthusiasts and professionals alike.

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BMW Coolant Expansion Tanks

Coolant Expansion Tank - E46 (non-M), X3, X5 3.0

OEM Coolant Expansion Tanks Kit - F22/23 F3X B48 B58

Cooling System Refresh Kit - Level 2 - E9x, E82, E88, Z4

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