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BMW Coolant Expansion Tanks for BMW 3 Series E46 (1999-2005)

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

10X Entries Into Our F80 M3 Sweepstakes

T#:338020

Part#: 17117573781

In Stock at Vendor

Sale - Save 9% $ 140.99

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

Starting at $ 128.98 USD

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Sale - Save 9%

$ 140.99

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

Starting at $ 128.98 USD

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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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ECS Cooling System Refresh Kit - Level 1

10X Entries Into Our F80 M3 Sweepstakes

T#:15677493

Part#: 11517527910-KT

In Stock

Sale - Save 4% $ 336.99

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

$ 324.43 USD

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Qty

Sale - Save 4%

$ 336.99

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

$ 324.43 USD

Add to Wish List

Stop the problems before they arise. If you vehicle has 80,000 miles or more, replace all of these components to ensure that your vehicle stays healthy. To keep everything in top order, continue to replace these components at 80,000 mile intervals. Water pump failure, cracked plastic housings, and expansion tank leaks will not be a concern once all these problem parts are replaced. This kit was put together by Turner including the basic parts that need replaced. Water pump with metal impeller Fan switch Thermostat and thermostat housing Sealing gaskets Expansion tank with level sensor, clamp and cap 1 Gallon Coolant Upper & lower radiator hoses

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ECS Cooling System Refresh Kit - Level 2

10X Entries Into Our F80 M3 Sweepstakes

T#:15677514

Part#: 11281706545-KT

In Stock

Sale - Save 3% $ 474.99

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

$ 460.24 USD

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Qty

Sale - Save 3%

$ 474.99

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

$ 460.24 USD

Add to Wish List

Stop the problems before they arise. If your BMW has 80,000 miles or more, replace all of these components to ensure that your vehicle stays healthy. Avoid water pump failure, cracked thermostat housings, and expansion tank leaks, which all lead to overheating and subsequent damage. This kit was put together by Turner for a complete cooling system service. GEBA water pump with metal impeller ECS aluminum water pump pulley Fan switch Thermostat and thermostat housing Sealing gaskets Expansion tank with level sensor, clamp and cap 1 Gallon Coolant Upper & lower radiator hoses Accessory drive belts Radiator drain plug

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Cooling System Refresh Kit - Level 2

10X Entries Into Our F80 M3 Sweepstakes

T#:15744066

Part#: 11287837898-KT

Ships on Dec 7, 2026

Sale - Save 26% $ 808.99

This product was last offered at the strikethrough price on
07-15-2026

$ 596.54 USD

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Qty

Sale - Save 26%

$ 808.99

This product was last offered at the strikethrough price on
07-15-2026

$ 596.54 USD

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BMW has been designing notoriously failure-prone cooling systems since the late 1980s. The coolant capacity in most BMW engines is not sufficient to accommodate any driving or overheating near red zone temperatures. After the gauge reaches this critical area, it is common for thousands of dollars in damage to occur. Stop the problems before they arise. If your vehicle has 80,000 miles or more, replace all of these components to ensure that your vehicle stays healthy. To keep everything in top order, continue to replace these components at 80,000 mile intervals. Water pump failure, cracked housings, and expansion tank leaks will not be a concern once all these problem parts are replaced. Saleri water pump with metal impeller ECS aluminum water pump pulley Fan switch Vaico Q+ thermostat - made in Germany! Sealing gaskets Expansion tank with level sensor, clamp and cap 1 Gallon Coolant Upper & lower radiator hoses Accessory drive belts Radiator drain plug

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Bav Auto Coolant Expansion Tank - E53 X5, E46, E83 X3

10X Entries Into Our F80 M3 Sweepstakes

T#:640496

Part#: 17137787039

In Stock

Sale - Save 18% $ 61.99

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

$ 50.99 USD

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Qty

Sale - Save 18%

$ 61.99

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

$ 50.99 USD

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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. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.

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Bav Auto Expansion Tank Mounting Plate - E46 Non-M w/ Manual Trans ...

For vehicles with a manual transmission only

10X Entries Into Our F80 M3 Sweepstakes

T#:638088

Part#: 17111436250

In Stock

Sale - Save 20% $ 44.99

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

$ 35.99 USD

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Qty

Sale - Save 20%

$ 44.99

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

$ 35.99 USD

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This Bav Auto part is the mounting bracket from the radiator to the expansion tank on an E46 3 series with a Manual Transmission. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.

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Bav Auto Expansion Tank Mounting Plate - E46 Non-M w/ Auto Trans ...

For vehicles with an automatic transmission only

10X Entries Into Our F80 M3 Sweepstakes

T#:638089

Part#: 17111436251

In Stock

Sale - Save 20% $ 45.99

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

$ 36.79 USD

Add to Wish List

Qty

Sale - Save 20%

$ 45.99

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

$ 36.79 USD

Add to Wish List

This Bav Auto part is the mounting bracket from the radiator to the expansion tank on E46 3 series and E85/E86 Z4 with an Automatic Transmission. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.

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Bav Auto Expansion Tank Cap - E36 E46 E34 E39 E32 E38 E65 X3 X5 Z4 ...

10X Entries Into Our F80 M3 Sweepstakes

T#:640208

Part#: 17117639022

In Stock

Sale - Save 15% $ 13.99

This product was last offered at the strikethrough price on
06-03-2026

$ 11.89 USD

Add to Wish List

Qty

Sale - Save 15%

$ 13.99

This product was last offered at the strikethrough price on
06-03-2026

$ 11.89 USD

Add to Wish List

This radiator expansion tank cap is used most BMW's from 1991-2006. It is a common failure item. When this item fails, it cannot hold pressure which results in your BMW overheating. If you are overhauling your coolant system, now is the time to consider preventative replacing this cap. It is also referred to as the coolant reservoir cap. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.

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BMW Coolant Expansion Tanks for BMW 3 Series E46 (1999-2005)

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

ECS Cooling System Refresh Kit - Level 1

ECS Cooling System Refresh Kit - Level 2

Cooling System Refresh Kit - Level 2

Bav Auto Coolant Expansion Tank - E53 X5, E46, E83 X3

Bav Auto Expansion Tank Mounting Plate - E46 Non-M w/ Manual Trans ...

Bav Auto Expansion Tank Mounting Plate - E46 Non-M w/ Auto Trans ...

Bav Auto Expansion Tank Cap - E36 E46 E34 E39 E32 E38 E65 X3 X5 Z4 ...

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