[elhombre]

Try draining some of the fluid out of the radiator, just enough to get the fluid level below the upper tank. Use your pressure tester and pump it up with air. Spray soappy water on the area and look for the bubbles.

The oem clamps are better than the cheap screw type because when the system goes through heat cycles, it expands and contracts. The rubber hose will slowly become cut by the sharp edges of the cheap clamps where the tighnening screw rides on. OEM clamps don't have these little edges to cut into the hose. The problem with OEM clamps is that they will relax and loose tension over time. Or worse, break in half while driving down the road. The constant-tension clamps are the best. You will only find the constant-tension clamps on big deisel rigs because they preform better. But, they are NOT cheap.