Open Hood. Locate the hood release underneath the dashboard of your BMW 3-Series Pull the lever until you hear the BMW hood pop open. Next, you need to release the hood safety latch at the front of your 3-Series.
Lift the hood and secure it in the open position.
Locate the Coolant Reservoir. Next, you locate the coolant reservoir (tank) on your BMW. This is where you can check the coolant level and add coolant if the level is low. On a 3-Series, the coolant expansion tank is located on the passenger side of the engine. Open the cap slowly. Open the cap only when the engine has cooled down.
Check BMW 3-Series Coolant Level Remove cap. Look at the coolant reservoir tank and note the low and high levels. If the level is below the minimum mark, you will need to add coolant, or your 3-Series may overheat. BMW 3-series uses the floating device to determine the coolant level.
Add engine coolant/antifreeze. Only add coolant type recommended by BMW.