Stepless Spring Clamp For Thermal Cycle Applications, 2.9375 - 3.3125 Inch Clamping Range, 0.35 Inch Width

These stepless spring clamps are indeed used for radiator hoses connecting to engine blocks, as well as thermostat housings to water pumps, and water pumps to oil coolers.

Fit comes down to the clamping range, and this one spans 2.9375 to 3.3125 inches. If your hose outside diameter at the clamp point is around 3 inches, that falls inside the range.

Silicone hoses are actually where this clamp shines. The torque requirement runs between 12 and 18 lb-in, which is on the lower end compared to a lot of band clamps. That low installation torque is specifically what keeps silicone from getting stressed or distorted during tightening. The spring also keeps constant pressure against the hose as it expands and contracts with heat cycles, so you're not dealing with a clamp that goes slack and lets coolant weep out.