2009 BMW X5 3.0L - SWEET SMELL - STEAM UNDER HOOD - ENGINE OVERHEAT
Heated antifreeze will have a syrupy odor. Remember to never open a cooling system while engine is hot. Be patient and wait till engine is cool down. Always make sure there's no pressure on the coolant hoses. Easiest way to find leak on most engine is to top it off with water and seal the system then look for leak. For these engine, the most common leak will be the auxiliary water pump or coolant reservoir. On this specific vehicle it was the coolant reservoir. Make sure you bleed the coolant system after replacing fail component. Simply let it run with the cap off so when thermostat open, system will fill the air gaps. Let it cool down and top it off.