[36thEVACVet]

Replace the radiator cap.

It's not venting and is causing a vacuum in the system during cool down.

Actually it isn’t drawing coolant back from the expansion tank under vacuum, right? I don’t think modern systems ever “vent”.

 

[willy92]

You may be correct, but, the cap keeps the coolant from transferring and somehow, causing a vacuum that causes that radiator hoses to collapse due to the coolant cooling and condensing.