Collapsed top radiator hose
 

Own a 1998 Civic LX with 120K miles - The top radiator hose keeps collapsing after I drive it and it cools down I find the hose is collapsed. When I open the radiator cap, the top hose springs to normal (there must be some kind of pressure or suction)

I replaced the radiator cap, cleaned out the overflow container and lines to ensure it wasn't blocked, replaced top radiator hose and bleed the air out of the radiator.

I doesn't over-heat, but concerned that something isn't working correctly

What else should I check?

That's odd. Have you made totally sure that the coolant system is completely full? When bleeding the system, do you have the climate control set to full heat?

well if its just not fully round i wouldnt worry about it much...
my old civic was like that and it never was a problem.

Hose flat as a pancake LOL

Radiator is full of fluid and I turned the heat on HOT and full blast when I bleed system
(I bleed the cooling system by raising the front-end, took the rad. cap off, turned on engine, turn on heat full blast, let run for 5 minutes with cap off, then put rad. cap back on)

Thanks for the input

well if its that bad you can always pull those hose off and see about buying a internal spring to shove in the hose. that will keep the hose from collapsing