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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

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

T#:640208

Part#: 17117639022

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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 Coolant Expansion Tank - E53 X5, E46, E83 X3

T#:640496

Part#: 17137787039

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Sale - Save 18% $ 61.99

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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

T#:638088

Part#: 17111436250

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Sale - Save 20% $ 44.99

This product was last offered at the strikethrough price on
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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 Water Pipe - E46 E39 Z4 Z3 (M52TU, M54)

T#:638085

Part#: 11537502525

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05-03-2026

$ 40.79 USD

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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

T#:638080

Part#: 11531705210

In Stock

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This product was last offered at the strikethrough price on
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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Bav Auto Expansion Tank Mounting Plate - E46 Non-M w/ Auto Trans ...

For vehicles with an automatic transmission only

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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This product was last offered at the strikethrough price on
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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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Water Connection Pipe

T#:15511839

Part#: 17111707817

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Sale - Save 20% $ 18.99

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05-03-2026

$ 15.19 USD

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Connects the radiator to the expansion tank

BMW E46 M54 AAF Low Temp Thermostat Kit - Partial

T#:7624632

Part#: 116211.2

Ships in 2 Business Days

$ 85.00 USD

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$ 85.00 USD

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BMW E46 M54 AAF Low Temp Thermostat Kit - Partial is an essential upgrade for enthusiasts looking to optimize engine performance and reliability. Developed by Advanced Auto Fabrication (AAF), this kit addresses the limitations of the factory M54 thermostat, which maintains a temperature range of 80-103°C and opens the mechanical failsafe at 110°C. For race conditions where maintaining a lower temperature is crucial, this kit replaces the stock electronic thermostat with a manual unit, allowing the engine to run at a safer and more efficient temperature. This upgrade not only enhances engine longevity but also reduces stress from high-temperature operation, minimizes heat soak, and increases power.

Optimal Temperature Control: Replaces the factory thermostat for improved engine temperature management.
Enhanced Engine Longevity: Operates at safer temperatures, reducing stress and extending engine life.
Increased Power: Lower operating temperatures can lead to better engine performance.
Reduced Heat Soak: Helps prevent overheating and ensures efficient cooling.
Improved Reliability: Manual thermostat unit offers more consistent performance in racing conditions.

Partial Kit Contents:

Thermostat housing plate
Thermostat
Installation hardware

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AAF Transmission Crossmembers 5-Speed - E46 Non-M

Fits ZF and Getrag Transmissions. Non-M models Only

T#:7608860

Part#: 116110

In Stock at Vendor

$ 190.00 USD

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$ 190.00 USD

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Since 2010, Advanced Auto Fabrication has been producing and developing both parts and full fledged race cars. Their knowledge base covers a wide range of vehicles both domestic and imported. In the specific case of BMW, the team at AAF has a particular affinity for building and designing components for BMW race cars. Ideal for the SE46 racing series, the AAF E46 5-speed Transmission Crossmember is a heavy-duty and worthwhile upgrade. The OEM thin cast aluminum cross member has been known to fail in multiple different ways. When using stiff engine and transmission mounts, the cross member can crack out and break around these mounting points. The cross member can also break from the high amounts of load transferred through the drive train. While chassis flex from hard cornering is being applied through the engine and transmission from the front cross member, this load is sent from the transmission back into the chassis at the transmission cross member. This is simply too much stress for the OEM cross member to hold up to under the extreme punishment of road racing. The AAF E46 Transmission Cross Member is completely constructed of 1/4' thick heavy-duty aluminum plate. It is designed specifically to cope with hours of endurance racing.

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BMW E46 AAF Aluminum Radiator Mounting Kit

T#:7608839

Part#: 11641

In Stock at Vendor

$ 189.00 USD

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$ 189.00 USD

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BMW E46 AAF Aluminum Radiator Mounting Kit provides a robust solution for mounting an aluminum radiator into the BMW E46 chassis without relying on the stock plastic mounts. Developed by Advanced Auto Fabrication, a company renowned for their expertise in producing high-performance race car components, this kit reflects their extensive knowledge and dedication to BMW race car design.

The mounting kit is designed to replace the stock mounting system and is compatible with lightweight aftermarket fans, as the stock electric fan cannot be used. Please note that this kit does not fit M3 models.

Durable Construction: Made from high-quality aluminum for strength and longevity.
Enhanced Cooling Efficiency: Allows for the use of aftermarket fans for improved cooling performance.
Race-Ready Design: Reflects Advanced Auto Fabrication's expertise in BMW race car components.
No Stock Plastic Mounts: Provides a more reliable and robust mounting solution than the factory system.

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AAF Low Temp Thermostat Kit - Full Kit - E46

T#:7624630

Part#: 116211

In Stock at Vendor

$ 175.00 USD

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$ 175.00 USD

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Since 2010, Advanced Auto Fabrication has been producing and developing both parts and full fledged race cars. Their knowledge base covers a wide range of vehicles both domestic and imported. In the specific case of BMW, the team at AAF has a particular affinity for building and designing components for BMW race cars. The factory M54 thermostat is electronically controlled to keep the engine running between 80-103°C, whereas race cars like to maintain 80°C or less for maximum power. Additionally, the mechanical failsafe doesn’t open up until the coolant temperature reaches 110°C, or 230°F, which is about the point when most race cars are turned off and parked which is no good for the motor! The AAF E46 M54 Low Temp Thermostat Kit is designed to give the control of proper engine operating temperature back by replacing the stock electronic thermostat with a manual unit. This allows the engine to run at the proper, and much safer, operating temperature, improving engine longevity, reduces stress from high-temp. operation, reduces heat soak, and increases power! Full Kit Contents: Thermostat housing Thermostat housing plate Thermostat install hardware sealant

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AAF E46 Radiator Fan Shroud

T#:7624641

Part#: 116251

In Stock at Vendor

$ 140.00 USD

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$ 140.00 USD

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Since 2010, Advanced Auto Fabrication has been producing and developing both parts and full fledged race cars. Their knowledge base covers a wide range of vehicles both domestic and imported. In the specific case of BMW, the team at AAF has a particular affinity for building and designing components for BMW race cars. AAF has created a light-weight fan shroud for your E46 race car. Equipped with 7 flaps to let as much air through as possible at speed and fits a 14' fan. Seamlessly attaches to the AAF Radiator Mounts. The shroud creates a vacuum to expand the fan’s ability to pull from the entire surface area of the radiator. This creates cooler temps under the hood with the benefit of 7 flaps that allow the most air to pass through. **AAF states fitment has only been thoroughly tested with their radiator mounts. No fitment info for the stock plastic mounts is available at this time. AAF has created a light-weight fan shroud for your E46 race car. Equipped with 7 flaps to let as much air through as possible at speed and fits a 14' fan. Seamlessly attaches to the AAF Radiator Mounts. The shroud creates a vacuum to expand the fan’s ability to pull from the entire surface area of the radiator. This creates cooler temps under the hood with the benefit of 7 flaps that allow the most air to pass through. **AAF states fitment has only been thoroughly tested with their radiator mounts. No fitment info for the stock plastic mounts is available at this time. *Does not include fan.

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AAF E46 Transmission Crossmembers - 6-Speed Non-M

For use with solid front engine mounts only!

T#:7624639

Part#: 116222

In Stock

$ 190.00 USD

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$ 190.00 USD

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Since 2010, Advanced Auto Fabrication has been producing and developing both parts and full fledged race cars. Their knowledge base covers a wide range of vehicles both domestic and imported. In the specific case of BMW, the team at AAF has a particular affinity for building and designing components for BMW race cars. Ideal for the SE46 racing series, the AAF E46 6-speed Transmission Crossmember is a heavy-duty and worthwhile upgrade. The OEM thin cast aluminum cross member has been known to fail in multiple different ways. When using stiff engine and transmission mounts, the cross member can crack out and break around these mounting points. The cross member can also break from the high amounts of load transferred through the drive train. While chassis flex from hard cornering is being applied through the engine and transmission from the front cross member, this load is sent from the transmission back into the chassis at the transmission cross member. This is simply too much stress for the OEM cross member to hold up to under the extreme punishment of road racing. The AAF E46 Transmission Cross Member is completely constructed of 1/4' thick heavy-duty aluminum plate. It is designed specifically to cope with hours of endurance racing.

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AAF E46 Transmission Crossmembers - 6-Speed M

For M Models

T#:7624640

Part#: 116223

Ships in 4 Business Days

$ 190.00 USD

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$ 190.00 USD

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Since 2010, Advanced Auto Fabrication has been producing and developing both parts and full fledged race cars. Their knowledge base covers a wide range of vehicles both domestic and imported. In the specific case of BMW, the team at AAF has a particular affinity for building and designing components for BMW race cars. Ideal for the SE46 racing series, the AAF E46 6-speed Transmission Crossmember is a heavy-duty and worthwhile upgrade. The OEM thin cast aluminum cross member has been known to fail in multiple different ways. When using stiff engine and transmission mounts, the cross member can crack out and break around these mounting points. The cross member can also break from the high amounts of load transferred through the drive train. While chassis flex from hard cornering is being applied through the engine and transmission from the front cross member, this load is sent from the transmission back into the chassis at the transmission cross member. This is simply too much stress for the OEM cross member to hold up to under the extreme punishment of road racing. The AAF E46 Transmission Cross Member is completely constructed of 1/4' thick heavy-duty aluminum plate. It is designed specifically to cope with hours of endurance racing.

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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

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$ 14.99

This product was last offered at the strikethrough price on
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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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