BMW Coolant Expansion Tanks for BMW Z Series E85/6 (2003-2008)

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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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ECS Tuning Aluminum Coolant Bleeder Screw
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ECS - Corporate Logo
T#:363070
Part#: 003530ECS01A
Ships on Aug 8, 2025
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$ 20.39 USD
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$ 20.39 USD
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Replace the flimsy plastic bleeder screw used in the coolant expansion tank or in one of the cooling system hoses with this high quality, durable, aluminum bleeder screw. The stock plastic screw can deform over time due to heat or even regular use. We have even seen the head of the screw snap off, leaving the threaded body stuck in the expansion tank. This aluminum screw will help to prevent sudden failure of the bleeder screw, which can result in immediate overheating of the car.

ECS Tuning's Aluminum Coolant Bleeder Screw replaces Genuine BMW Part Number 17111712788

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Genuine BMW - Corporate Logo
T#:207187
Part#: 17117639022
In Stock
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$ 24.24 USD
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$ 24.24 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/ Auto Trans ...
For vehicles with an automatic transmission only
Bavarian Autosport - Corporate Logo
T#:638089
Part#: 17111436251
In Stock
Sale - Save 9% $ 44.99
$ 40.99 USD
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$ 40.99 USD
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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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Expansion Tank Retaining Plate
For vehicles with automatic transmission only
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URO - Corporate Logo
T#:362912
Part#: 17111436251
Ships in 2 Business Days
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$ 48.14 USD
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$ 48.14 USD
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Mounts to the side of the radiator for retaining the expansion tank

Genuine BMW - Corporate Logo
T#:22487
Part#: 17107836448
Ships Jul 3, 2025
5% off MSRP $ 164.00
$ 154.99 USD
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5% off MSRP $ 164.00
$ 154.99 USD
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Genuine BMW Expansion Tank
This item fits the following BMW Chassis:
E85 Z4M,E85 Z4,E86 Z4

Fits BMW Engines including:
S54

Bremmen Parts - Corporate Logo
T#:1195932
Part#: 17112248409
Ships Jul 15, 2025
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$ 29.09 USD
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$ 29.09 USD
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Located underneath the expansion tank

Bavarian Autosport - Corporate Logo
T#:640208
Part#: 17117639022
In Stock
Sale - Save 15% $ 11.99
$ 10.19 USD
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$ 10.19 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. 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 - Corporate Logo
T#:2766
Part#: 17111742231
In Stock
$ 15.99 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 Parts - Corporate Logo
T#:640140
Part#: 17111712788
In Stock
$ 4.99 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.

Meyle Expansion Tank Cap
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Meyle - Corporate Logo
T#:579357
Part#: 3148009004
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$ 6.76 USD
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Replace worn or missing pieces.
Expansion Tank Mounting Clamp
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URO - Corporate Logo
T#:591954
Part#: 17111707777
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$ 5.23 USD
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Locks the expansion tank into the mounting plate via the large hole in the bottom of the tank
OEM Rein Expansion Tank Cap - BMW E32 E34 E36 E38 E39 E46 & More ...
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Rein - Corporate Logo
T#:340541
Part#: 17111742231
Ships Jul 10, 2025
$ 13.99 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.
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2 Pin Connector
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ECS - Corporate Logo
T#:33412932
Part#: 61132359999
Ships on Aug 11, 2025
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$ 6.49 USD
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$ 6.49 USD
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Includes connector housing with terminals and seals. Commonly used for the coolant level sensor.

ECS Tuning replacement harness connectors include all necessary pins and wire seals for a complete harness repair. Whether you have a broken harness connector or need a complete wiring repair, we have the components you need.

Each connector includes an additional terminal in case one becomes lost or damaged during installation.

*OEM cross reference PN# 61132359999 - Commonly used for the coolant level sensor.

Please reference the original part number from the existing connector to confirm fitment, before ordering.

Suggested tools:

Suggested crimping pliers: T#387193
Wire De-pin tools:
12pc De-Pin Tool Set - T#386379
23pc De-Pin Tool Set - T#641943

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Fluid Level Sensor
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Meyle - Corporate Logo
T#:5973204
Part#: 17117546548
Special Order: No Guaranteed ETA
$ 12.99 USD
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MEYLE-ORIGINAL: True to OE fluid level sensor. Used in multiple locations. Wulf Gaertner Autoparts AG manufactures and markets automotive spare parts under its MEYLE brand. Since its foundation in 1958, Wulf Gaertner Autoparts has been an owner-operated, unlisted family business on the aftermarket scene. Since 1995, Wulf Gaertner Autoparts AG has been manufacturing and trading under its MEYLE brand. They pride themselves on top-grade quality-tested spare parts for passenger cars, vans and commercial vehicles. Comparable OE Cross Reference - 17117546548
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URO Radiator Mounting Plate for Expansion Tank - Z4
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URO - Corporate Logo
T#:639486
Part#: 17112248408
Back Ordered
Sale - Save 3% $ 56.99
$ 55.14 USD
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$ 55.14 USD
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URO Parts is one of the leading manufacturers of high quality direct replacement aftermarket components, covering a wide range of makes and models. All of their replacement parts are manufactured to ISO 9000 certification standards, so you can expect long lasting performance from URO Parts. As a leading source of high performance BMW parts and accessories since 1993, we at Turner Motorsport are honored to be the go-to supplier for tens of thousands of enthusiasts the world over. With over two decades of parts, service, and racing experience under our belt, we provide only quality performance and replacement parts. All of our performance parts are those we would (and do!) install and run on our own cars, as well as replacement parts that are Genuine BMW or from OEM manufacturers. We only offer parts we know you can trust to perform! URO Mounting Plate - This item fits the following BMW Chassis: E85,E86 Fits BMW Engines including: M54,N52
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