Some radiators split in area of the neck by the place the hose fits to .Take a good look at it you might need to repair the neck of the radiator .If its split it could be hard to see it .But if you can find the crack, rough it up with sand paper , and then give it a nice coat of epoxy glue .The radiator needs to be dry to do it right .And dont lock up the hose clip to tight , this to will split the neck of the radiator. I put a little sealer on the neck ,then put the hose on ,next screw up the clamp . .