I noticed this problem a few months ago when I checked my oil after the car was parked overnight. Both the upper and lower rad hoses were sucked down. Assumed the cap was not venting properly, so replaced that and the issue went away.

Today I find that after sitting overnight my lower hose is collapsed again. Upper hose was normal. Even after I opened the cap I had to flex the lower hose to get it round again.

Anyone else seen this happen? I assume it's just time to replace the lower hose? 92k miles, all original hoses, they are in nice condition otherwise.
I suppose it might be possible I have a defective pressure cap?

 

I believe this is normal for a "bad" hose that has become soft over time. Some lower rad hoses even have an internal coil of metal like a spring to keep hoses from collapsing.


How many miles on the car and /or hose?