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

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.

If you plan to drive your BMW aggressively on the track, it is important that you upgrade your cooling system to avoid overheating. To ensure your BMW keeps cool on the track, we have built out our new High Performance Cooling System Upgrade kits. Featured in this kit is everything you will need to redo your cooling system from top to bottom with OEM components, with select stock components swapped out for the high performance alternative! This kit includes a high performance Mishimoto Radiator, for significantly better cooling than the stock radiator and full aluminum construction that won't crack from long term heat cycling, a performance Mishimoto 70*C thermostat, for lower temperature operation and increased cooling of the engine, and a Stewart High Performance Water Pump, for dramatically increased coolant flow at all RPMs. 

Additional items included in this kit:

• OEM Replacement Coolant Hoses
• OEM Expansion Tank, Cap, and Level Sensor
• OEM Belts, Tensioners, and Pulleys
• OEM Auxiliary Fan Switch
• Genuine BMW Hardware for Easy Installation
• ECS Tuning Aluminum Water Pump Pulley - For increased reliability over the stock composite pulley

Just like the rest of your vehicle's major systems, the cooling system must also be addressed periodically to ensure proper cooling and component reliability. Plastic and rubber components become brittle and prone to splitting or cracking after long periods of heating and cooling cycles, especially in colder climates! The coolant itself can degrade or become contaminated, leading to potential corrosion or freezing issues. Finally, thermostats and sensors can fail completely, preventing proper cooling and/or coolant temperature readings to become inaccurate.

To make sure you are not left stranded on the side of the road with an overheated engine, we have put together this Basic Cooling System Service kit. This kit contains all of the most-likely-to-fail components, giving you peace of mind knowing your engine will continue to run cool for another 60,000+ miles.

See kit contents below for all included components.

As the E46 M3 gets on in years and mileage, the cooling system will be one of the areas that needs the most attention. We have packaged all of the major cooling components into one overhaul kit:

• radiator
• water pump
• thermostat
• radiator hoses and clamps
• gaskets and o-rings

We have found that the E46 M3 can develop inconvenient cooling issues, even on daily driven street cars. While the infamous radiator and water pump failures of the E36 are a thing of the past, the E46 M3 still has its own complications. The best approach to avoid bigger problems is preventative maintenance. We recommend replacing the water pump before 80,000 miles and the radiator before 100,000 miles. By addressing these problem areas before a failure, you will save yourself a larger repair bill in the future.

In addition to the standard cooling package items above, there are several other cooling-related components that may make sense to do at the same time:

• Original BMW coolant
• fan clutch
• main serpentine belt and A/C belt
• Turner Power Pulley Kit (because now is the perfect time!)

This cooling overhaul package fits:
2001-2006 E46 BMW M3
 

If you plan to drive your BMW aggressively on the track, it is important that you upgrade your cooling system to avoid overheating. To ensure your BMW keeps cool on the track, we have built out our new High Performance Cooling System Upgrade kits. Featured in this kit is everything you will need to redo your cooling system from top to bottom with OEM components, with select stock components swapped out for the high performance alternative! This kit includes a high performance Mishimoto Radiator for significantly better cooling than the stock radiator and full aluminum construction that won't crack from long term heat cycling, and a Genuine BMW Motorsport 55*C thermostat, for lower temperature operation and increased cooling of the engine. 

Additional items included in this kit:

• ECS Tuning Silicone Replacement Coolant Hoses - For increased reliability over stock rubber hoses
• ECS Tuning Heavy Duty Aluminum Bleeder Screw
• OEM Expansion Tank, Cap, and Level Sensor
• OEM Belts, Tensioners, and Pulleys
• OEM Auxiliary Fan Switch
• Genuine BMW Hardware for Easy Installation
• ECS Tuning Aluminum Water Pump Pulley - For increased reliability over the stock composite pulley

Due to weak rubber and plastic construction, vital cooling system parts are prone to premature failure. Key components, such as radiator hoses, the thermostat, and the expansion tank are particularly prone to cracks, leaks, and catastrophic failure, which can lead to overheating and potentially severe engine damage. Fortunately, our team of experts has assembled this kit of high-performance alternatives and high-quality OE replacement components, both tailored to safeguard your cooling system from failure and increase cooling system capability.

Our Level 2 High-Performance Cooling System Service Kit is the ultimate solution for ensuring long-term reliability and enhanced cooling performance. Each component in this comprehensive kit has been carefully selected by our team of enthusiasts to address common failure points and provide a robust, performance-oriented upgrade for your vehicle. By replacing aging factory parts with premium, high-performance alternatives, you’ll optimize cooling efficiency and safeguard your engine from the stress of overheating.

Our all-inclusive "Level 2" High-Performance Cooling System Service Kit includes:

Turner Motorsport Heavy Duty Aluminum Expansion Tank ECS Silicone Radiator Hoses ECS Aluminum Water Pump Pulley Wahler Thermostat (80°C) Bremmen Aluminum Water Pump Bremmen Parts Auxiliary Fan Switch Continental Accessory Belt ECS Kevlar-Reinforced A/C Compressor Drive Belt Genuine BMW Water Pump O-Ring Genuine BMW Water Pump Bolts Genuine BMW G48 Antifreeze (1 Gallon) Redline Water Wetter Performance Coolant Additive (12 oz.)

Unlike factory rubber hoses, silicone can withstand higher temperatures and pressures with minmal wear. Rubber will wear out and weaken so don't let it bite you when it counts! Silicone has been proven during extreme racing conditions and won't be the weak link that ruins your day.

This kit is specifically designed for the enthusiast that wants uprated cooling hoses, but also wants to address the heat-cycled plastic connectors and o-rings that are also prone to failure in higher mileage or older vehicles.

This E46 M3 ECS silicone hose set replaces two hoses - 
11537830716, upper radiator hose 
11537830715, lower radiator hose 

Both thermostat housing hoses to replace your worn out rubber and brittle plastic connections.

Over the years and with exposure to extremely hot coolant, the coolant hoses in your vehicle can take a beating. Being made of reinforced rubber, these hoses can fail in a number of ways. Splitting at a hose clamp, swelling, cracking, and breaking are just a few of the ways this hose can leave you stranded. Replace it at the first sign of wear to keep your coolant in your engine.

Comes with both upper and lower thermostat hoses: 11537830715 Lower + 11537830716 Upper

Replace your cracked or leaking radiator hose to prevent further leaks and potentially catastrophic failure. This hose replaces the lower radiator hose that connects the radiator to the thermostat housing.

This Lower Radiator Hose fits the following BMWs:
2001-2006 E46 3 Series M3, M3 Convertible