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
Sale - Save 40% $ 33.99
$ 20.39 USD
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Sale - Save 40% $ 33.99
$ 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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Sale - Save 9% $ 44.99
$ 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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Vargas Turbo Technologies - Corporate Logo
T#:7530036
Part#: COOLANTCAPBLUE
In Stock
$ 78.99 USD
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$ 78.99 USD
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VTT is proud to offer their billet replacement for the factory plastic Coolant Reservoir cap. This cap does away with the weak plastic cap while adding some pop, and color to your engine bay. This coolant cap retains ALL of the factory provisions by simply allowing you to snap the factory pressure-relief into the new Billet Cap. VTT also designed these caps to complement their N5X Billet Oil caps, N5XBillet Oil filter housing caps, and Billet Power Steering cap, so all 4 will have the same design. These caps are offered in 4 colors – Red, Black, Blue, and Clear anodized Replaces Genuine BMW Reservoir Cap # 17117639020 Note: Fitment includes 99% of all BMW with a coolant Reservoir tank from the E series forward, meaning then fit even the brand New G8X M3/4 with the S58, all B58, etc. If your BMW is an E90 or newer this cap most likely will fit
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Expansion Tank Mounting Bracket - E46 E85 Z4 - Auto Trans
For vehicles with automatic transmission only
Genuine BMW - Corporate Logo
T#:12560
Part#: 17111436251
In Stock
Sale - Save 5% $ 86.99
$ 82.47 USD
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$ 82.47 USD
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This Genuine BMW part is the mounting bracket from the radiator to the expansion tank on E46 3 series and E85/E86 Z4 with Automatic Transmission.

When doing any sort of repair or maintenance there is no replacement for genuine factory parts. Turner Motorsport carries the Genuine BMW brand with pride and has the parts you need to complete your next project with confidence.

This item fits the following BMWs:
1999-2005 E46 BMW 323i 323ci 325i 325ci 325xi 328i 328ci 330i 330ci 330xi
2003-2008 E85 BMW Z4 2.5i Z4 3.0i Z4 3.0si
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Coolant Expansion Tank
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URO - Corporate Logo
T#:363421
Part#: 17117573751
Ships in 2 Business Days
Sale - Save 4% $ 60.99
$ 58.30 USD
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$ 58.30 USD
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Does not include cap or coolant level sensor

MMX Performance - Corporate Logo
T#:29002094
Part#: MMR03-1502
Ships in 6 Business Days
$ 121.99 USD
$ 121.99 USD
The MMX Performance 90mm billet coolant expansion cap for BMWs has been designed from the ground up in the UK, from a solid piece of billet aluminum. Each cap was designed to directly replace the OE cap, not merely stuck in place. Fitment is for models with the matching OE (17 11 7 639 021) part number.
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VTT Billet Coolant Reservoir Cap - Anodized Clear - Most BMWs 2006+ (...
This coolant cap retains ALL of the factory provisions by simply allowing you to snap t...
Vargas Turbo Technologies - Corporate Logo
T#:7530035
Part#: COOLANTCAPRAW
Ships in 4 Business Days
$ 78.99 USD
Free Shipping
$ 78.99 USD
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VTT is proud to offer their billet replacement for the factory plastic Coolant Reservoir cap. This cap does away with the weak plastic cap while adding some pop, and color to your engine bay. This coolant cap retains ALL of the factory provisions by simply allowing you to snap the factory pressure-relief into the new Billet Cap. VTT also designed these caps to complement their N5X Billet Oil caps, N5XBillet Oil filter housing caps, and Billet Power Steering cap, so all 4 will have the same design. These caps are offered in 4 colors – Red, Black, Blue, and Clear anodized Replaces Genuine BMW Reservoir Cap # 17117639020 Note: Fitment includes 99% of all BMW with a coolant Reservoir tank from the E series forward, meaning then fit even the brand New G8X M3/4 with the S58, all B58, etc. If your BMW is an E90 or newer this cap most likely will fit
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Genuine BMW - Corporate Logo
T#:45825
Part#: 17112248408
Ships Jul 1, 2025
Sale - Save 6% $ 75.99
$ 71.61 USD
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Sale - Save 6% $ 75.99
$ 71.61 USD
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Genuine BMW Mounting Plate -
This item fits the following BMW Chassis:
E85,E86

Fits BMW Engines including:
M54,N52


Vargas Turbo Technologies - Corporate Logo
T#:7530033
Part#: COOLANTCAPBLK
Ships on Jul 14, 2025
$ 79.99 USD
Free Shipping
$ 79.99 USD
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VTT is proud to offer their billet replacement for the factory plastic Coolant Reservoir cap. This cap does away with the weak plastic cap while adding some pop, and color to your engine bay. This coolant cap retains ALL of the factory provisions by simply allowing you to snap the factory pressure-relief into the new Billet Cap. VTT also designed these caps to complement their N5X Billet Oil caps, N5XBillet Oil filter housing caps, and Billet Power Steering cap, so all 4 will have the same design. These caps are offered in 4 colors – Red, Black, Blue, and Clear anodized Replaces Genuine BMW Reservoir Cap # 17117639020 Note: Fitment includes 99% of all BMW with a coolant Reservoir tank from the E series forward, meaning then fit even the brand New G8X M3/4 with the S58, all B58, etc. If your BMW is an E90 or newer this cap most likely will fit
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Rein Expansion Tank Mounting Plate - E46, Z4
For vehicles with automatic transmission only
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Rein - Corporate Logo
T#:402139
Part#: 17111436251
In Stock
$ 61.99
$ 52.99 USD
Limited Qty Sale
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$ 61.99
$ 52.99 USD
Limited Qty Sale
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Mounts to the side of the radiator for retaining the expansion tank
Vargas Turbo Technologies - Corporate Logo
T#:7530034
Part#: COOLANTCAPRED
In Stock
$ 79.99 USD
Free Shipping
$ 79.99 USD
Free Shipping
VTT is proud to offer their billet replacement for the factory plastic Coolant Reservoir cap. This cap does away with the weak plastic cap while adding some pop, and color to your engine bay. This coolant cap retains ALL of the factory provisions by simply allowing you to snap the factory pressure-relief into the new Billet Cap. VTT also designed these caps to complement their N5X Billet Oil caps, N5XBillet Oil filter housing caps, and Billet Power Steering cap, so all 4 will have the same design. These caps are offered in 4 colors – Red, Black, Blue, and Clear anodized Replaces Genuine BMW Reservoir Cap # 17117639020 Note: Fitment includes 99% of all BMW with a coolant Reservoir tank from the E series forward, meaning then fit even the brand New G8X M3/4 with the S58, all B58, etc. If your BMW is an E90 or newer this cap most likely will fit
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Genuine BMW - Corporate Logo
T#:7457
Part#: 17117573751
In Stock
$ 254.99 USD
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$ 254.99 USD
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This high quality Genuine BMW brand expansion tank is used on M54 and N52 engines, and is a common failure item on all E85 Z4's. Be leary of competitors selling this part for less -- is it a Genuine BMW? Probably not.

If you are overhauling your coolant system, now is the time to consider preventative replacing this expansion tank. These are known to go bad, causing a leak which can leave you stranded. 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.

When doing any sort of repair or maintenance there is no replacement for genuine factory parts. Turner Motorsport carries the Genuine BMW brand with pride and has the parts you need to complete your next project with confidence.

This item fits the following BMWs:
2003-2008 E85 BMW Z4 2.5i Z4 3.0i Z4 3.0si
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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
Sale - Save 4% $ 49.99
$ 48.14 USD
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Sale - Save 4% $ 49.99
$ 48.14 USD
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Mounts to the side of the radiator for retaining the expansion tank
Genuine BMW - Corporate Logo
T#:45828
Part#: 17112249366
Ships Jul 1, 2025
5% off MSRP $ 128.99
$ 122.99 USD
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5% off MSRP $ 128.99
$ 122.99 USD
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Genuine BMW Thermostat -
This item fits the following BMW Chassis:
E85

Fits BMW Engines including:
M54


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
Sale - Save 3% $ 29.99
$ 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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Sale - Save 15% $ 11.99
$ 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
Free Shipping on orders $49 and up
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
In Stock
Sale - Save 38% $ 10.99
$ 6.76 USD
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Sale - Save 38% $ 10.99
$ 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
In Stock
Sale - Save 13% $ 5.99
$ 5.23 USD
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Sale - Save 13% $ 5.99
$ 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
Sale - Save 35% $ 9.99
$ 6.49 USD
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Sale - Save 35% $ 9.99
$ 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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Sale - Save 3% $ 56.99
$ 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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