 The hoses have zero pressure in them when the engine's off or they're flat. A lot of times the cap is bad, and that's why it's important whenever you're flushing coolant on a vehicle, either test or replace the radiator cap. And I see so many cars that have not had that done. People come in and say, I just had my coolant flushed, so I'm sure it's fine, but my hoses are flat. That is such a weird thing, by the way, to someone who doesn't,