The thermostat regulates the temperature of your coolant. At a predetermined temperature the thermostat will open to let coolant flow to the radiator and be cooled by airflow or the fan. Over time the thermostat will become stuck open or closed, leading to a variety of issues. A closed thermostat will never allow the coolant to reach the radiator and be cooled. Hot coolant will continue to circulate through the engine and absorb even more heat until boiling and the system overheats. An open thermostat is not as bad but is still not ideal - the coolant is always cool, with the temp needle always reading in the cool range. This tells the ECU to richen the fuel mixture to bring the car up to normal operating temp. So your fuel mileage decreases and the car runs rich.  

Replacing the thermostat is an easy but messy job. This thermostat includes the main o-ring (but a housing gasket may be required). Consider replacing the housing and any associated temp sensors while you're in there. The cooling system will need to be bled after.  

Most of the engines from the mid-1980s through the 1990s use the same thermostat design and they are interchangeable among the different temperatures. This is the 68*C thermostat, at the bottom of the temperature range. It should only be used in racing situations such as when deleting the engine fan. However, keep in mind that BMW spent a lot of time engineering the cooling system to work in all kinds of conditions and changing thermostat temperature is not recommended to fix any failures in the cooling system.  

Mishimoto makes coolant tanks, radiators and much more for your Mini/BMW. Established in 2003 their commitment to absolute quality in the aftermarket world is evident through the quality and performance enhancing products they offer.
 

This thermostat fits the following BMWs:   
1977-1983  E21 BMW  323i  
1986-1991  E30 BMW  318is 318ic 325e 325es 325i 325ic 325is 325ix  
1992-1999  E36 BMW  318i 318is 318ti 318ic 323is 323ic 325i 325is 325ic 328i 328is 328ic M3  
1982-1988  E28 BMW  528e  
1986-1988  E28 BMW  535i  
1989-1995  E34 BMW  525i 535i  
1997-1998  E39 BMW  528i  
1986-1989  E24 BMW  635csi  
1988-1994  E32 BMW  735i 735il  
1997-2000  Z3 BMW  Z3 2.8 M Roadster M Coupe 

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.

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

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

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

This OEM Hella/Mahle-Behr engine fan clutch fits BMW E46 M3, Z3 M Roadster, M Coupe 2001-2002, E34 535i & M5, and E32 735i 735il. Made to the same or higher standards of quality as the genuine part, ensuring proper fan control and cooling. Failed fan clutches can result in overheating due to the fan not spinning fast enough to deal with excess heat or can cause poor engine performance when a clutch has locked up causing the fan to be fully engaged permanently.

Hella is a premium manufacturer that supplies automotive parts to numerous car brands across the world. Everything from electrical to mechanical genuine parts have been made and supplied directly to BMW before the vehicles ever leave the production floor. Their high quality, long lasting parts have made them a trusted brand chosen to help keep your BMW on the road for many years to come.

As a leading source of high performance BMW parts and accessories since 1993, we at Turner Motorsport are honored to be the go-to supplier for tens of thousands of enthusiasts the world over. With over two decades of parts, service, and racing experience under our belt, we provide only quality performance and replacement parts.  All of our performance parts are those we would (and do!) install and run on our own cars, as well as replacement parts that are Genuine BMW or from OEM manufacturers. We only offer parts we know you can trust to perform!

This item fits the following BMWs:
2001-2006 E46 BMW M3
1989-1993 E34 BMW 535i M5
1988-1992 E32 BMW 735i 735il
2001-2002 Z3 BMW M Roadster M Roadster

The ECS Exact-fit water line is a perfect upgrade if you're tired of dealing with brittle failure prone parts under your hood. The reinforced fluorosilicone hose has been pre-formed to route the same way your stock line did so you can maintain that clean factory installed appearance. Upgrading the line fitting with a billet aluminum piece eliminates the failure prone plastic fitting giving your cooling system strength.

Included:

Aluminum fitting

• Material: 6061-T6 Aluminum - MIL-A-8625F Type II Class 2 black anodized for superior corrosion resistance and strength
• Single-piece design avoiding additional interfaces that may cause leaks
• Matches OEM style connection to upper coolant hose

Silicone hose

• Material: Black Reinforced Fluorosilicone Lined Coolant Safe Silicone
• Pre-formed hose to ensure OEM style routing and appearance
• Can maintain the use of your stock retaining clips to route the hose in identical locations (due to slight variations in silicone the retainer on the expansion tank may not fit)
• Pressure tested to ensure 2X operating pressures to ensure reliability