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BMW Cooling System Parts & Accessories for BMW E46 M3 S54 (1999-2005)

The cooling system is arguably the weakest point in numerous BMWs. If you drive an aging BMW or plan on taking your car to the track like we do, we recommend beefing up your cooling system before going to the track. Generally, the main components in your cooling system that are prone to failure include the following: expansion tank, factory hoses, water pump, thermostat, fan (especially if your vehicle comes factory with a clutch fan), and radiator. Factory BMW expansion tanks are plastic and prone to either breaking off at connection points or combusting. As factory rubber hoses age they either crack or break over time - we offer silicone cooling hose upgrades for most applications to avoid future failures. If you have an older vehicle, your water pump likely comes from the factory with a plastic impeller - we offer upgraded water pumps with metal impellers that are far more reliable. Newer model BMWs utilize electric water pumps - BMW spent millions of dollars engineering these water pumps, but they fail so often that we recommend replacing at 60,000 mile service intervals to avoid being stranded on the side of the road. In terms of thermostats, we offer various upgraded thermostats for racing applications. If your BMW utilizes a clutch fan from the factory, we have several options available in terms of universal electric fans - we recommend replacing these to avoid sending brittle plastic fan blades through your hood. For radiators, we recommend swapping out your radiator for one that does not use plastic connection points like your factory radiator.

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Moroso Performance Aluminum Expansion Tank - E46 M3

T#:568945

Part#: 63793

In Stock at Vendor

$ 433.99 USD

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$ 433.99 USD

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If you have ever experienced a leaking plastic BMW expansion tank you will realize the value of this aluminum version straight away. Even if a failure has not happened to you, it's easy to tell this tank is much stronger and more durable than the plastic used in the stock design. The original BMW plastic tanks suffer from leaks and failures with no warning. While being lightweight and recyclable, the design and construction of the stock tank is just not up for reliable long-term use. Moroso coolant expansion tanks are all pressure tested for guaranteed leak-free operation. Features: Direct bolt-in replacement to stock, cracked, or discolored tanks Fabricated Aluminum for strength, factory tanks fail after repeated high heat situations & age No cutting of factory hoses is required and accepts the factory clip-on hose Included is a Moroso Part No. 63324 racing radiator cap that operates in the same pressure range as the factory cap The Moroso radiator cap mounts to a billet aluminum neck that will not strip out like plastic threaded necks Easy to read slight level is included

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Active Autowerke Sport Fan Clutch - E36 E46

T#:397219

Part#: 14-010

Ships in 2 Business Days

5% off MSRP $ 259.00

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

$ 246.99 USD

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5% off MSRP

$ 259.00

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

$ 246.99 USD

Add to Wish List

When you push your powerplant, thermodynamics push right back. The toll of high performance is higher heat load – and many stock components begin to complain. But Active Autowerke has you covered - this upgraded fan clutch increases viscous coupling of cooling fan blade speed to water pump speed, yielding increased airflow through the radiator for more efficient cooling. A simple, yet wonderful, thing.

This product fits the following BMWs:
1992-1999 E36 323i 325i 328i 330i M3
1998-2006 E46 323i 325i 328i 330i M3

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

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

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Sale - Save 15%

$ 13.99

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

$ 11.89 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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Bav Auto Temperature Sensor - BMW E39 E46 E9X E60 F01/02

T#:639833

Part#: 13621433076

In Stock

Sale - Save 20% $ 14.99

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

$ 11.99 USD

Add to Wish List

Qty

Sale - Save 20%

$ 14.99

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

$ 11.99 USD

Add to Wish List

This is the coolant temperature sensor used in many BMW models from the late-1990s to the mid-2010s. The engine computer relies on the coolant temp to set the fuel mapping for the engine. As the car warms up the computer changes the fuel mixture. If your car is running a bit rich (too much fuel) it could be because this sensor is failing and not sending the correct info to the computer. This sensor is located in a variety of places depending on the engine. But it's one of those easy replacement items 'while you're in there' when doing a water pump or thermostat replacement. 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 Cooling System Parts & Accessories for BMW E46 M3 S54 (1999-2005)

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Moroso Performance Aluminum Expansion Tank - E46 M3

Active Autowerke Sport Fan Clutch - E36 E46

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

Bav Auto Temperature Sensor - BMW E39 E46 E9X E60 F01/02

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