I can understand the clamps not having the same clamping pressure with the smaller OD hoses. This causes seepage. I have been putting a small amount of silacone sealer on the bottom side of lip on the thermastat housing, radiator inlet and outlet ends and at the bottom of the water
pump before slipping hoses on and clamping them. I install the clamps on the bottom side on the lip
at all those location. Heater hose nipples as well. Seems to work.

logan426