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

Our Turner Motorsport's full aluminum expansion tank was designed and engineered in house to help with the weak point in your E46 cooling system. The coolant expansion tank goes through heat cycles over and over again from regular driving, it is important that your expansion tank is doing its job to retain coolant to keep your engine operating temperatures down and keep your engine bay clean. Not only is this a major upgrade but also a great maintenance item to replace. Our expansion tank was designed to fit the OEM hoses for an easy install and comes with all the upgraded items you will need for a clean install.

If your BMW needs a new expansion tank, make sure this is the last expansion tank you ever need to buy. Our coolant expansion tank has a full aluminum construction and wrinkle black powder coat for durability. Expansion tank kit comes with all the accessories you need to replace your expansion tank once, and never have to worry about it again.

Product Features:

Maintains stock coolant capacity and expansion volume
Designed to maintain OE coolant elevation, preventing air pockets
Baffled tank ensures that air pockets cannot be introduced during aggressive driving and provides accurate coolant level reading
Carefully designed bleed passage prevents the introduction of air as the engine cools
Turner engraved internal fill level
TIG welded 5052 aluminum construction
All bungs are machined to fit factory hose ends
Kit contents:

Turner Aluminum Expansion Tank
Coolant level sensor
Expansion tank cap
Flared coolant pressure release line
Hardware for installation
Product Development:

Turner expansion tanks are designed, engineered, tested and quality inspected by our Research and Development team at Turner. Nothing but the highest level of precision and quality through leading-edge product development technology including FARO laser scanning for reverse engineering and quality inspection, SolidWorks 3D CAD modeling, rapid prototyping utilizing our in-house 3D printer and rigorous long term product testing.

BMWs are well-known for their problematic cooling systems, which are often a catalyst for irreversible engine damage and a hefty repair bill. The coolant expansion tank—a crucial component responsible for holding hot engine coolant under high pressure—is a common cause of cooling system issues. Unfortunately, BMW chose to manufacture the factory E46 M3 expansion tank out of plastic. After years of exposure to high coolant temperatures, ambient engine bay heat, and chemical-rich antifreeze, the plastic degrades, eventually weakening enough to fail catastrophically.

With this issue in mind, our team of BMW enthusiasts engineered the ultimate cooling system upgrade for E46 M3 owners: a heavy-duty expansion tank built to last! Crafted from durable 5052 TIG-welded aluminum, this tank resists high temperatures and pressures without degrading over time. Unlike the fragile OEM plastic tank, Turner’s design eliminates the risk of cracking, leaking, or failure. Upgrade to our Heavy Duty Aluminum Expansion Tank Kit and say goodbye to expansion tank issues for good!

To guarantee exact fitment, the upgraded tank was designed using advanced 3D CAD modeling. All bungs, nipples, and fittings are precision-machined to ensure a secure seal with factory hose ends. Unlike other aftermarket options, this tank maintains the factory coolant capacity and includes our laser-cut logo plate at the top, providing an accurate fill level. Internal baffles are incorporated to prevent fluid cavitation, eliminating air pockets in the cooling system and avoiding false coolant level warnings during spirited driving.

Engineered for high-performance builds and daily drivers alike, this expansion tank boasts a premium wrinkle black powder coat finish for a clean "OEM+" aesthetic. This tough coating not only enhances appearance but also protects against corrosion for long-term durability. The kit includes a silicone overflow hose, a high-quality level sensor, and an OE expansion tank cap, offering a complete cooling system upgrade. Avoid the risks of the factory expansion tank—upgrade your E46 M3 today and drive with confidence!

Features & Benefits:

Durable 5052 TIG-Welded Aluminum Construction: Ensures long-term reliability and eliminates expansion tank failure. Premium Wrinkle Black Powder Coat Finish: Offers an "OEM+" appearance while preventing corrosion. Factory Coolant Capacity Retention: Maintains the same coolant level as the original design. Laser-Cut Turner Logo Plate: Provides a clear and accurate fill level indicator. Internal Baffles: Prevent the introduction of air pockets during high-performance driving. Precision-Machined External Bungs and Fittings: Ensure a perfect fit for factory hose connections. Kit Includes:

Turner Motorsport Aluminum Expansion Tank Performance Silicone Coolant Overflow Hose Expansion Tank Cap Coolant Level Sensor Product Development:

Our Heavy Duty Aluminum Expansion Tank was designed, engineered, tested, and quality inspected by our Research & Development team. Our development process includes leading-edge product technology: FARO laser scanning for reverse engineering and quality inspection, SolidWorks 3D CAD modeling, rapid prototyping utilizing our in-house 3D printer, and rigorous long-term product testing.

The auxiliary fan in your vehicle serves an extremely important role. When your car reaches temperatures that may be hazardous to your engine, the auxiliary fan moves air through the radiator to provide better cooling. Usually activated during times of stationary vehicle operation, it supplements the air usually driven through the radiator by driving down the road.

If your vehicle is getting too hot during traffic or at stop lights, your auxiliary fans are probably faulty. Replace yours with this piece from Bremmen Parts to restore the factory cooling in your vehicle and prevent catastrophic damage to your engine. Even if your fans are still operational but the blades are damaged or cracked, replacement is the only solution.

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

Over time, prolonged exposure to high-temperature coolant can take a toll on your vehicle's hoses. Made from reinforced rubber, these hoses are prone to wear and failure in various ways, including splitting at hose clamps, swelling, cracking, or breaking. Any of these issues can lead to coolant loss and potentially leave you stranded. Replacing your hoses at the first sign of wear is essential to maintaining a properly functioning cooling system.

This replacement hose is designed with the correct diameter, bends, and length for a precise fit, making it an ideal solution for swelled or damaged hoses. With straightforward installation, this hose provides peace of mind, whether you're embarking on a long road trip or simply commuting to work.

When replacing your radiator hose, some coolant loss is unavoidable. Browse our website to find the exact replacement coolant and other parts for your vehicle, delivered straight to your door. Don’t forget to order a new thermostat housing as well—factory plastic units often crack or warp during removal, and replacing them ensures a complete and reliable repair.

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.