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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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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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$ 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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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 Heater Inlet Pipe - E46 E39 E53 E83 E85 Z3

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T#:638080

Part#: 11531705210

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$ 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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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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$ 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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Bavarian Autosport Radiator Hose - Upper - E46 M52 M54

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T#:640204

Part#: 17127510952

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$ 27.74 USD

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Replacement Upper Radiator Hose for E46 3 series (Non-M3). We recommend replacing the Coolant Temperature Sensor while replacing this hose as the original sensor is often damaged while trying to remove it from the old hose. 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

10X Entries Into Our F80 M3 Sweepstakes

T#:638089

Part#: 17111436251

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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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Thermostat With Housing

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T#:26494584

Part#: 11537509227

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Bav Auto Radiator Hose - Lower - E46 M52 M54

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T#:640203

Part#: 11531436408

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$ 31.20 USD

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OEM Replacement Lower Radiator Hose for E46 3 series (Non-M3). We recommend replacing the Coolant Temperature Sensor while replacing this hose as the original sensor is often damaged while trying to remove it from the old hose. 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 Hose

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T#:27572101

Part#: 64218376153

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$ 38.34 USD

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Radiator Hose - Lower

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T#:38655188

Part#: 11537830715

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$ 22.53 USD

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Radiator Hose - Upper

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T#:38621426

Part#: 11537830716

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$ 20.39 USD

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Mishimoto Water Pump - BMW M50, M52, M54, S50, S52

T#:51075091

Part#: MMWP-M50-92

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$ 72.99 USD

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$ 72.99 USD

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The Mishimoto Performance Water Pump provides the thermal stability required for modified engines.

Genuine BMW Radiator Support Bracket - E92 Z4 E65 E60 E53 E46 E66 E83...

T#:21736

Part#: 17117514402

Ships in 3 Business Days

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

$ 24.86 USD

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Genuine BMW Bracket F.Radiator
This item fits the following BMW Chassis:
E46 M3,E85 Z4M,E53 48IS,E46,E53 X5 X5,E65,E83 X3,E85 Z4,E86 Z4,E90,E92,E93

Genuine BMW Radiator Bracket - Lower - E46

T#:21734

Part#: 17111436264

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$ 30.54 USD

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Genuine BMW Bracket F.Radiator
This item fits the following BMW Chassis:
E46 M3,E46,E85 Z4

Fits BMW Engines including:
M52,M54,M56,S54

Genuine BMW Heater Hose

T#:14120

Part#: 64218363198

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

$ 36.50 USD

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BMW Hose F Water Valve And Radiator -
This item fits the following BMW Chassis:
E46

Genuine BMW Coolant hose - E46 M3

T#:150726

Part#: 64216902679

Ships in 3 Business Days

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

$ 32.31 USD

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Genuine BMW Hose F Water Valve And Radiator
This item fits the following BMW Chassis:
E46 M3,E46

Mishimoto Thermostat W/ Housing & Sensor - BMW M52, M54, M56 Engines ...

T#:51075086

Part#: MMTS-E46-99E

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$ 91.99 USD

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The Mishimoto Thermostat Assembly focuses on precision fitment and long-term durability.

Hex Bolt & Washer Kit

T#:55245856

Part#: 0711990XXKTKT

Ships in 3 Business Days

$ 35.31 USD

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Turner Motorsport offers this Genuine BMW Hex Bolt and Washer Kit to keep your chassis maintenance or engine refresh completely up to factory standard.

Automatic Transmission Thermostat

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T#:15511829

Part#: 17 111437362

Ships on Sep 23, 2026

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$ 36.85 USD

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Heat exchanger for your automatic transmission, usually changed when you replace your expansion tank.

Bremmen Parts Water Pump - E46 M3 S54

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T#:36981065

Part#: 11517838159

Ships on Dec 2, 2026

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$ 110.97 USD

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A failing water pump is a recipe for engine overheating and costly internal damage. Keep your coolant flowing and your engine protected by replacing your aging pump with this high-quality OE unit from Bremmen Parts.

Water pump replacement is suggested at 60,000 - 80,000 miles.

This pump includes the alignment dowel, sealing gasket, and thermostat sealing o-ring. We recommend picking up a water pipe sealing o-ring (11537830712) and thermostat (11531318274) for a comprehensive service.

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Heater Hose

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T#:38621424

Part#: 64218363198

Ships in 6 Business Days

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$ 8.66 USD

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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

Water Pipe - M54 E46 E58 E83

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T#:36981061

Part#: 11537502000

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$ 18.50 USD

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Water pipes play a crucial role in maintaining proper engine cooling. If cracked, they must be replaced immediately to prevent engine overheating. This water pipe runs from the rear of the water pump housing to the expansion tank hose. It comes complete with all necessary seals for a hassle-free installation.

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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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$ 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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Bremmen Auxiliary Fan Temperature Switch - E46 E39 E9X E60 E70 E53 ...

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#:640141

Part#: 13621433077

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$ 16.79 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

Water Pump Installation Hardware Kit

T#:55209926

Part#: 0071199KT

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$ 8.59 USD

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This Genuine BMW water pump installation hardware kit is the exact factory refresh package needed to maintain the structural integrity of your cooling system's plumbing.

Oil Cooler Line O-Ring & Screw Kit

T#:55281750

Part#: 1722OCLKT

Ships in 3 Business Days

$ 20.60 USD

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This Genuine BMW Oil Cooler Line O-Ring & Screw Kit includes the exact factory components required to safely service your oil cooler hard lines.

Bremmen Engine Fan Blade - 11 Blades, 420mm - BMW M30 S38 M50 M52 S5...

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T#:640149

Part#: 11521712058

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$ 18.76 USD

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This fan is driven by the serpentine belt, engaged by the fan clutch. If you have bad motor mounts, it's quite common for the blades of this fan to make contact with the radiator or radiator shroud, essentially self-destructing the fan into many pieces. Be sure to get a new fan clutch, while you are replacing this.

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

10X Entries Into Our F80 M3 Sweepstakes

T#:639833

Part#: 13621433076

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Sale - Save 20% $ 14.99

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$ 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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Heater Hose

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T#:38621423

Part#: 64218376999

Ships in 6 Business Days

Sale - Save 22% $ 20.99

This product was last offered at the strikethrough price on
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$ 16.31 USD

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Radiator Fan Clutch

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T#:57304041

Part#: 11527831619

Ships on Dec 29, 2026

$ 75.99 USD

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Radiator Mount

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T#:56977984

Part#: 17117514402

Back Ordered

$ 6.99 USD

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$ 6.99 USD

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Maintain cooling system stability under spirited street driving and hard track use with this URO Parts replacement upper radiator mount bracket.

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