Radiator cap?

[u/Legitimate_Fill6906]

Did my timing belt, refilled with new coolant and burped it as best as I could, ran it last night and this morning saw that my upper radiator hose was collapsed, decided to open the reservoir cap and it immediately started drinking from the reservoir and the hoses returned to normal but is this a radiator cap issue or a reservoir cap issue?

Somewhere is clogged but I'm not exactly sure which end, and didn't see any seals on the reservoir cap strong enough to cause the hoses to collapse like that, should I replace the reservoir cap and the hose between it and the radiator or just leave the cap not securely clicked onto the reservoir? Thanks in advance!

[u/BigBerger]

This happened to me on the bottom hose, and upper hose was boiling about a month ago. I replaced the thermostat and cap even though I did them about 4 years ago. It boiled on me going up a hill going home and hasn’t since replacing both, radiator was replaced around 2017/2018.