Your hoses and plastic components are nearly 15 years old - replace them all. Carefully inspect the radiator as well. Because of your geographic location and potential exposure to corrosive salt spray on winter roads, the radiator may show evidence of possible failure points and should also be considered for replacement.

Not a cheap endeavor, but the peace of mind and enhanced reliability is worth it.

2002 X5 3.0 291,400 miles
2014 428i 13,000 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles