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?

 

ok, think i just fixed that problem. checked all the hoses on the overflow tank and found that the one that goes from tank to radiator was clogged full of crap at the cap. so as the engine heated and cooled, there was a huge vaccum created because of that line being blocked. cleaned it out with some wire, blew it out with a hand pump and test it tomorrow after going to work.

 

taught us all something thanks

good of you to figure it out and share it. This is how we all learn.

 

In my case it was the aftermarket radiator cap causing it. Replaced it with a shiny one from the dealer and the hose stopped collapsing.

 

A new Radiator cap will also fix that problem.