1997 Cadillac Catera Coolant water leak behind engine

It is a bit difficult. You need to remove the upper and lower intakes, the wiper arms, and the upper cowl cover/inlet vent. This will give you access, there is a door in the compartment under the removed cowl vent that can be removed as well, held on with a plastic 10mm nut. If it is original valve, it has spring type clamps on the three hoses that go to it. Another possibility of leaks that will run down the bellhousing are head gaskets(97 had an issue), the oil cooler cover(mounted in engine valley), and the coolant pipe that runs from the right(pass) side of engine to the rear. The heater control valve is the higher probability leak, that will leak with little or no pressure working against it.