If cooling system is under pressure, how can a hose collapse? The spring,my understanding was it was only supplied in certain vehicles for preventing collapse in the vacuum filling process. I would think the spring inhibit flow if anything.
If the impeller is pulling enough coolant from the radiator while the thermostat is closed it will collapse the hose. Think of how the flow of coolant through the system occurrs. Nail the throttle, pump spins faster pulling what it can including the hose. Collapsing hose is not uncommon.