BMWs are known for offering luxury motoring through vehicles that are jam-packed with intelligent German engineering and innovation. When well-maintained and serviced, these parts work seamlessly together for a driver experience that is smooth and effortless, ensuring that drivers feel at one with the car and the road.

However, without good maintenance practices, even the best designed car can start to show symptoms of failure. In this article, we will take a closer look at your BMW’s radiator and what happens when it begins to fail, causing your vehicle’s prized engine to overheat.


First, let’s take a closer look at the key parts of your BMW’s radiator. Knowing these will help you to understand where potential issues may lie and how best to respond to them.

  • Core: This is the largest part and represents the majority of your BMW’s radiator system. As you might expect, this core is where most of the radiator’s activity happens. The core looks like a large metal box with vents on it. This vent allow the radiator to remove heat from the coolant to the air that surrounds it instead. These vents expel this hot air through the grill at the front of your car. Depending on your model, your radiator may vary and can have 1, 2, or 3 cores.
  • Pressure Cap: The pressure cap is responsible for, as you might have guessed, sealing in and maintaining pressures within the coolant in the radiator system. This enables your coolant to absorb as much heat as possible without boiling over, meaning it can work to cool your engine comparatively longer than if it wasn’t under the pressure made by this cap.
  • Outlet/Inlet Tanks: These are relatively simple parts, whose sole purpose is to allow the hot coolant to move away from the engine and into the radiator for cooling. This process then moves back out to the engine when needed.
  • Transmission Cooler: Almost all cars will utilize the same coolant in both the engine as well as the transmission. This coolant will keep the transmission cooler pipes at a safe temperature, as the automatic transmission produces large amount of heat.
  • Overheating: If one of the above parts fail or struggles to do its job efficiently, your BMW will start to show symptoms of overheating. This will become more frequent when driving at higher speeds or in hotter weather, as both these factors will cause the engine to become hot. You may also notice your coolant needs refilling more often that usual, which is commonly due to the coolant being boiled away because of to incorrect pressures within the system. If the core vents become blocked, this will also prevent the hot air from escaping the vehicle efficiently, causing an overheating failure.


Below are some of the symptoms of overheating you should be on the lookout for:

  • Temperature warning light
  • High temperature guage
  • Hot oil/metal smell from engine often filtering through the AC
  • Thumping sounds from engine
  • Ticking sounds from engine
  • Leaked coolant
  • Steam coming from under the hood
  • Hood that is hot to the touch
  • Decrease in power
  • Complete engine failure


If your BMW is showing symptoms of overheating, then you need to take your vehicle in for diagnostics and repair as soon as you can. If left ignored, regular engine overheating can completely destroy your engine and its connected parts, causing your car to become undrivable. You will also likely be left with an excessive repair bill, possibly you without a vehicle for a considerable time.

Luckily, if you live in or around San Antonio or Longhorn, TX, you have no reason to delay in seeking repairs, as Autobahn Automotive is on hand to help. We are open five days a week, Monday through Friday, 7:30am – 5:30pm. This means you can easily schedule repair work around your working life or other commitments. Our dedicated and highly qualified team of experts are specialists in imported cars. We are rated number one for BMW servicing in San Antonio, and with 40 years of experience, it is not hard to see why. Come by or call for an appointment today.

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