What causes radiator hose to collapse?
been driving around the past couple days and today i popped the hood and saw that my upper radiator hose was sucked flat after it had sat a couple hours. i opened the cap and release the pressure and the hose opened back up to normal. it slowly does this as the engine cools down after driving. I cant figure out what would cause this. my coolant level is good, flow is good (already burped system). what would cause this?
'86 4x4 22R Reg Cab
Custom Tailgate, 32 x 11.50s