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.

Replace the Achilles heel of your factory cooling system with a stout and reliable mechanical thermostat setup.

The factory E46 thermostat housing is a combined unit featuring a plastic housing and a built in thermostat that you cannot replace separately. These plastic all-in-one units are commonly know to crack or fail causing a headache, a trip on the tow truck and possible damage to your engine.

Taking cues from the reliable M50 thermostat setup we designed a an assembly that not only converts your plastic housing into a billet aluminum unit but also swaps out the integrated thermostat for a separate replaceable thermostat. The ability to swap out thermostats separately from the whole housing opens up doors to changing thermostats to different temperature ratings based on your application while also providing lower maintenance costs. No longer do you have to replace the whole housing but just the thermostat itself.

The billet housing is designed to be utilized with E46 M3 upper and lower radiator hoses and also features -16 ORB connections for custom radiator hoses. A major upgrade from the factory and aftermarket plastic units. Our thermostat housing kit can be used by the savvy daily driver or the track hero who wants to ensure the durability of their cooling system.

Key benefits:

Uses M50/S50 mechanical thermostat for increased reliability
Option to use aftermarket colder thermostats if desired
Thermostat can be replaced separately for lower maintenance cost
Barbed hose connections for use with E46 M3 hoses or built in -16 ORB connections for custom radiator hoses
Design:

Machined out of a single piece of billet 6061 aluminum, this thermostat housing will withstand higher prolonged temperatures and abuse for performance applications
Black anodized with engraved Turner logo on the front to match the Turner Motorsports Power Steering Reservoir
Viton gasket for superior sealing performance
For use with E46 M3 radiator hoses 11537830715 and 11537830716
Kit contents:

6061 Billet Aluminum Thermostat Housing
Mechanical Thermostat
Thermostat Housing Gasket
Thermostat Harness
Optional Silicone or Rubber E46 M3 coolant hoses
Product Development:

Our Billet Thermostat Housing upgrade was 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.

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.

When it comes time to replace your thermostat, be sure you have everything you need. This kit includes everything you need to replace your thermostat, including the thermostat.

Kit includes:

• Mahle-Behr thermostat with gasket
• Thermostat mounting hardware
• 1 liter of coolant

Applications:
1999-2003 E39 528i, 525i, 530i sedan, touring wagon (M52TU engine, M54 engine)
1999-2005 E46 323, 328, 325, 330 sedan, coupe, cabrio, touring wagon (M52TU engine, M54 engine)
2004-2005 E60 525i, 530i sedan, touring wagon (M54 engine)
2001-2006 E53 X5 3.0 (M54 engine)
2004-2006 E83 X3 2.5i X3 3.0i (M54 engine)
1999-2002 Z3 2.3. Z3 2.5i, 2.8 Z3 3.0i (M54 engine)
2003-2005 Z4 2.5i, Z4 3.0 (M54 engine)

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.

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

This is a compete cooling system overhaul kit, which includes all the common cooling system failure parts bundled into a complete package. This cooling system package is for the E46 with the M52/54 engine.  

A failure in the cooling system can lead to overheating and catastrophic engine failure. Don't gamble your engine! By replacing these core items preventatively, such as the thermostat housing, radiator, and waterpump, you are defusing what could be a ticking cooling system time bomb. And if you've had a failure of one of these parts, now is the time to refresh your entire cooling system. Keep on top of the cooling needs of your engine for your own piece of mind. Potential buyers also see the upside of a properly maintained car with receipts. 

This cooling system overhaul kit fits the following BMWs: 
1999-2000 E46 3 Series Sedan/Wagon - 323i & 328i 
1999-2000 E46 3 Series Coupe/Convertible - 323Ci & 328Ci 
2001-2002 E46 3 Series Sedan/Wagon - 325i, 325xi, 330i, 330xi 
2001-2002 E46 3 Series Coupe/Convertible - 325Ci, 330Ci 

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

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

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.)