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

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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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Bav Auto Coolant Expansion Tank - E53 X5, E46, E83 X3
Bav Auto Coolant Expansion Tank - E53 X5, E46, E83 X3
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Bavarian Autosport - Corporate Logo
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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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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Genuine BMW Expansion Tank Cap - E3X / E53 / Z4
Genuine BMW Expansion Tank Cap - E3X / E53 / Z4
Genuine BMW - Corporate Logo
T#:207187
Part#: 17117639022
In Stock
21% off MSRP $ 34.96

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 27.67 USD
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21% off MSRP
$ 34.96

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 27.67 USD
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Genuine BMW Radiator Cap - 2,0Bar
This item fits the following BMW Chassis:
E36 M3,E39 M5,E46 M3,E85 Z4M,E53 48IS,E36,E38,E39,E46,E53 X5,E65,E83 X3,E85 Z4,E86 Z4,F06,F10,F12,F13

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Bav Auto Expansion Tank Mounting Plate - E46 Non-M w/ Manual Trans
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
Bavarian Autosport - Corporate Logo
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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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
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
Bavarian Autosport - Corporate Logo
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
Free Shipping on orders $49 and up
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Sale - Save 20%
$ 45.99

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

$ 36.79 USD
Free Shipping on orders $49 and up
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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Mahle-Behr Coolant Expansion Tank - E46, E53, E83
Mahle-Behr Coolant Expansion Tank - E46, E53, E83
Mahle-Behr - Corporate Logo
T#:1735
Part#: 17117573781
In Stock at Vendor
$ 100.99

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

$ 87.99 USD
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$ 87.99 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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URO Coolant Expansion Tank - BMW E46 M3
URO Coolant Expansion Tank - BMW E46 M3
2X Entries Into Our F80 M3 Sweepstakes
URO - Corporate Logo
T#:48608189
Part#: 17112283344
Ships in 1 Business Day
$ 155.99 USD
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$ 155.99 USD
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​This radiator coolant reservoir/expansion tank for E46 M3 is a common failure item as the plastic weakens and cracks, causing coolant leaks. If your E46 M3 has over 80k miles and still has the original expansion tank, we highly recommend replacing it during your next major service.
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Coolant Expansion Tank - E53 E46 E83 M52 M54
Coolant Expansion Tank - E53 E46 E83 M52 M54
2X Entries Into Our F80 M3 Sweepstakes
URO - Corporate Logo
T#:373103
Part#: 17137787039
Ships in 1 Business Day
$ 45.99 USD
Free Shipping on orders $49 and up
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$ 45.99 USD
Free Shipping on orders $49 and up
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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.
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Genuine BMW Cap - 17121719356 - E30,E46,E46 M3
Genuine BMW Cap - 17121719356 - E30,E46,E46 M3
Genuine BMW - Corporate Logo
T#:46115
Part#: 17121719356
Ships in 6 Business Days
3% off MSRP $ 31.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 30.99 USD
Free Shipping on orders $49 and up
Add to Wish List
3% off MSRP
$ 31.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 30.99 USD
Free Shipping on orders $49 and up
Add to Wish List


Genuine BMW Cap
This item fits the following BMW Chassis:
E46 M3,E30,E46

Fits BMW Engines including:
M20,S54,S62

Expansion Tank Retaining Plate
Expansion Tank Retaining Plate
For vehicles with automatic transmission only
2X Entries Into Our F80 M3 Sweepstakes
URO - Corporate Logo
T#:362912
Part#: 17111436251
Ships in 1 Business Day
$ 53.99 USD
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$ 53.99 USD
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Mounts to the side of the radiator for retaining the expansion tank
Expansion Tank Mounting Plate
Expansion Tank Mounting Plate
2X Entries Into Our F80 M3 Sweepstakes
URO - Corporate Logo
T#:584756
Part#: 17111436250
Ships in 1 Business Day
$ 49.99 USD
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$ 49.99 USD
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Replace your broken mounting plate to keep your expansion tank secure and prevent leaks.
OEM Behr Coolant Expansion Tank Cap 2.0 Bar - E36 E46 E34 E39 E32 E38 E65 X3 X5 Z4
OEM Behr Coolant Expansion Tank Cap 2.0 Bar - E36 E46 E34 E39 E32 E38...
Mahle-Behr - Corporate Logo
T#:2766
Part#: 17111742231
Ships in 3 Business Days
$ 20.99

This product was last offered at the strikethrough price on
08-13-2026

$ 19.99 USD
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$ 19.99 USD
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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.

Hailing from Stuttgart, Mahle-Behr specializes in automotive cooling systems. From air conditioning to engine cooling M-B has you covered with OE-quality replacement parts.

This item fits the following BMWs:
1990-1991 E30 BMW 318i 318is 318ic
1992-1998 E36 BMW 318i 318is 318ic 323is 323ic 325i 325is 325ic 328i 328is M3
1999-2005 E46 BMW 323i 323ci 325i 325ci 325xi 328i 328ci 330i 330ci 330xi M3
1989-1995 E34 BMW 530i 535i 540i M5
1991-1995 E34 BMW 525i
1997-2003 E39 BMW 525i 528i 530i 540i M5
1989-1994 E32 BMW 735i 735il 740i 740il 750il
1995-2001 E38 BMW 740i 740il 750il
2002-2008 E65 BMW 745i 745li 750i 750li 760i 760li
1990-1998 E31 BMW 840i 840ci 850i 850ci 850csi
2004-2011 E83 BMW X3 2.5i X3 3.0i X3 3.0si
2000-2006 E53 BMW X5 30.0i X5 4.4i X5 4.6is X5 4.8is
1996-2002 Z3 BMW Z3 1.9 Z3 2.3 Z3 2.5i Z3 2.8 Z3 3.0i M Coupe M Roadster
2003-2008 E85 BMW Z4 2.5i Z4 3.0i Z4 3.0si M Roadster M Coupe
2000-2003 E52 BMW Z8 Z8 Alpina
2007+ E90 BMW 335i & 335xi
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Bremmen Coolant Bleeder Screw - BMW E30 E36 E38 E39 E46 E83 E90 Z4
Bremmen Coolant Bleeder Screw - BMW E30 E36 E38 E39 E46 E83 E90 Z4 ...
10X Entries Into Our F80 M3 Sweepstakes
Bremmen Parts - Corporate Logo
T#:640140
Part#: 17111712788
Ships on Sep 16, 2026
$ 3.99 USD
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$ 3.99 USD
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Plastic bleeder screw for cooling system is used to bleed air that would otherwise create an air pocket and lead to overheating. Includes o-ring seal.
Bav Auto Expansion Tank Cap - E36 E46 E34 E39 E32 E38 E65 X3 X5 Z4
Bav Auto Expansion Tank Cap - E36 E46 E34 E39 E32 E38 E65 X3 X5 Z4 ...
10X Entries Into Our F80 M3 Sweepstakes
Bavarian Autosport - Corporate Logo
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
Free Shipping on orders $49 and up
Add to Wish List
Sale - Save 15%
$ 13.99

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

$ 11.89 USD
Free Shipping on orders $49 and up
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.
Show More Show Less
Expansion Tank Mounting Clamp
Expansion Tank Mounting Clamp
2X Entries Into Our F80 M3 Sweepstakes
URO - Corporate Logo
T#:591954
Part#: 17111707777
Ships in 1 Business Day
$ 6.99 USD
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$ 6.99 USD
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Locks the expansion tank into the mounting plate via the large hole in the bottom of the tank

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BMW Mini
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