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      09-16-2021, 10:46 PM   #5

Drives: '15 650i Convertible
Join Date: Apr 2018
Location: US

iTrader: (0)

And just to add, nothing is corroding on those lines. That crusty stuff is just baked coolant. It gets real hot under there because the exhaust manifolds and turbos are on top - thus the reason they call this design a "Hot V" engine. With all those heat and cooling cycles those rubber hoses lose their elasticity and are no longer adequately compressed by the metal clamps. Thus you get some leakage when the cooling system is under pressure. I should also add that I have to add some coolant once a year - although the low-level warning does not trigger - and those hoses on my car still look perfect. Same on my X3. I have no idea where it goes.
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