Silicone is elastic, and elastic materials creep. Under a clamp the wall compresses, then keeps compressing slowly as the material takes a set, and the clamp load falls with it. A joint that was tight when it went on can be noticeably looser after the hose has been through a few heat cycles carrying pressure.
That is normal behaviour rather than a defect, and it is why a re-check belongs to fitting a hose instead of being a sign that something was done badly. The distinction that matters is between a hose that has settled, which needs its clamp load restored, and one that was never seated on its bead, which needs to be repositioned before it is tightened again.
Most silicone hoses for charge air and coolant carry a raised bead near each end, and the clamp belongs just behind it, on the side away from the joint. The bead stops the hose being pushed off under pressure and the clamp provides the seal. Put the clamp on the wrong side of the bead and the bead does nothing at all.
The common error is clamping straight onto the bead, which distorts the hose and leaves a gap on either side of the high point. Slide the hose fully onto the pipe, ease it back until the bead just clears the pipe end, then clamp behind the bead. In that position the hose is held mechanically as well as sealed.
A relaxed hose is soft, sits flat under the clamp, and seals again once the clamp load is restored. A damaged hose has gone hard, has a glazed or chalky surface, or has swollen where it contacts fluid. A cut hose carries a visible bite mark where a clamp edge or a wire has pressed into the wall.
Only the first is a re-tightening case. A hardened performance silicone hose will not seal reliably again, because the material has lost the give that made the seal work. A cut hose has a stress riser that will split under pressure, and no clamp load rescues a wall that is already severed partway through.
You can check clamp load without taking anything apart. With the engine cold, try to rotate the hose on its pipe by hand. It should resist firmly and move only slightly. If it spins freely, the clamp has lost its grip. Then look at the band itself: a gap opening between band and hose tells the same story.
Do not loosen a clamp just to see whether it was tight. Breaking the seal on a hose that is currently sealing creates a leak where there was none, and re-clamping a disturbed joint is less reliable than leaving a good one alone. Check by feel and by eye, then decide whether any action is actually needed.
A charge air hose is pushed off its pipe by pressure and pulled by engine movement, so it needs retention as much as sealing, which is why bead and clamp position matter most there. A coolant hose sees pressure pulses and sustained heat, so its failure mode is usually the material going hard at the hottest end rather than the joint creeping.
That difference changes the check. On a charge hose, look for the hose having crept along the pipe towards the joint, and for an oil mist at the clamp that shows a weep. On a coolant hose, squeeze the wall at the hottest end and compare it with the cold end; a hose that has lost its give there is on its way out.
Replace rather than re-tighten when the hose has been off and on enough times that the wall under the clamp no longer springs back, when a clamp has cut into the reinforcement, or when the hose has run with a leak and taken on the fluid it was carrying. All three leave a hose that will keep asking for attention.
For a one-off hose the same judgement applies with one addition: confirm the replacement will be the same shape. On a custom silicone application the hose is often the part that absorbs a routing change, so a replacement made to a slightly different drawing loads the joints differently and can undo a fit that was working.
