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BMW Cooling System Parts & Accessories for BMW 3 Series E46 (1999-2005)

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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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Bav Auto Thermostat With Aluminum Housing - M52TU M54

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T#:12544802

Part#: 11531437040

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05-03-2026

$ 84.99 USD

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The plastic thermostat cover in your BMW is a known point of failure. Throughout years of repeated contact with hot coolant, the plastic can crack and cause massive coolant leaks and potential overheating. Eliminate one of the weak links in your cooling system with a replacement aluminum thermostat housing. By installing this aluminum unit, you have no worries as far as plastic housing cracks go

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

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T#:640496

Part#: 17137787039

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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

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T#:638088

Part#: 17111436250

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Sale - Save 20% $ 44.99

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$ 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 Heater Inlet Pipe - E46 E39 E53 E83 E85 Z3

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T#:638080

Part#: 11531705210

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05-03-2026

$ 32.79 USD

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This is the plastic heater inlet pipe that connects the cylinder head to the heater inlet on cars with the M52 or M54 engine. The plastic on this hose becomes brittle over time and eventually leads to failure. Replace yours with a brand new Bav Auto Heater inlet pipe to prevent catastrophic failure.

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Bavarian Autosport Water Pipe - E46 E39 Z4 Z3 (M52TU, M54)

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T#:638085

Part#: 11537502525

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This plastic water pipe is positioned directly underneath your intake manifold. Due to its plastic construction, it is notorious for catastrophic failure. Rapid cooling loss and overheating are both direct results of this failure, posing permanent and lasting damage to the engine.

Replace your cracked/broken coolant pipe with this high-quality Bavarian Autosport component to ensure long-term reliability and perfect fitment.

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

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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

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$ 36.79 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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Meyle Coolant Expansion Tank - E53 X5, E46 M52/54, E83 X3

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T#:369184

Part#: 17117573781

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$ 66.99 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.

Other items to consider replacing at the same time are the radiator cap, coolant level sensor, lower radiator hose, coolant temp sensor, 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.

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!

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Water Pump and Seal - with upgraded metal impeller - MEYLE

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T#:579324

Part#: 11517509985

Ships on Nov 18, 2026

$ 52.99 USD

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Ensure the optimal performance of your BMW by addressing the crucial component of the water pump. Turner Motorsport provides high-quality water pumps designed to keep coolant flowing smoothly. If left unchecked, a failing water pump can lead to overheating issues, potentially causing damage to engine internals. Common among German vehicles, water pump failure may result in unnecessary visits to the repair shop. Preventive maintenance, especially during timing belt replacements, is essential to avoid rapid coolant temperature rise and potential engine damage.

Prevents overheating issues
Guards against engine damage
Common replacement during timing belt maintenance
Ensures smooth coolant flow for optimal engine performance
Options for thermostats available on Turner Motorsport's website
Convenient coolant replacement options
Recommended replacement around 60,000 miles

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Meyle Expansion Tank Cap

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T#:579357

Part#: 3148009004

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05-15-2026

$ 8.99 USD

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Replace worn or missing pieces.

Water Connection Pipe

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T#:15511839

Part#: 17111707817

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$ 15.19 USD

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Connects the radiator to the expansion tank

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

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T#:640208

Part#: 17117639022

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Sale - Save 15% $ 13.99

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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

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T#:639833

Part#: 13621433076

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

$ 11.99 USD

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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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Fluid Level Sensor

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T#:5973204

Part#: 17117546548

Special Order: No Guaranteed ETA

$ 13.99 USD

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$ 13.99 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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Meyle - Coolant Hose - Lower Right E46

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T#:40478120

Part#: 11531436408

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$ 32.99 USD

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Upgrade your BMW’s cooling system with a dependable solution that meets or exceeds OEM quality.

Auxillary Fan Switch

Mounted in upper radiator hose, controls operation of auxiliary fan Mounted in lower radiator hose, controls operation of auxiliary fan

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T#:4934936

Part#: 3148210000

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$ 18.99 USD

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The auxiliary fan switch activates the auxiliary cooling fan to provide additional cooling under high heat loads, and when the car is stationary. Also known as the coolant temperature sending unit, comes with related o-ring

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Coolant Flange - Rear/Engine Block

Fits European models only

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T#:55533481

Part#: 11531708808

Special Order: No Guaranteed ETA

$ 9.99 USD

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This Meyle Original-grade replacement coolant flange is the perfect solution for refreshing your BMW’s cooling plumbing back to factory-fresh operation.

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