At the radiator or overflow tank. Do not add water, add coolant.
the washer water filler is located in the boot of the 850
How much does it cost to replace a water pump on a bmw 325 i
The water and coolant is put in the coolant reservoir for the location of this refer to the owners manual. It is best to do this when the engine is cold otherwise you run the risk of getting boiling water all over you. the mixture of coolant to water should be about 50/50.
No
How do I install a water pump on a 2003 BMW 325? I have install water pumps on a lot of different makes of automobiles but never on a BMW. Anything special I need to know?
In the radiator
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You will get the answer at this forum: http://bimmer.roadfly.com/bmw/forums/e32/
Only use BMW coolant and distilled water.