1995 BMW 525i Over heats

water should still do the job of keeping engine cool, although it is not nearly as good as coolant becaues it does boil quicker and also can rust up the inner parts of the cooling system. this would be the first thing to replace, even if it doesn't help the overheating it still needs replaced , in my opinion. make sure the radiator cooling fan(s) come on properly and that there is no air in the cooling system.

And bleed out all the air, the screw on top of the radiator expansion tank.