Hi all - weird issue...

71 cutlass with 350 -

When the engine is cold - the TOP radiator hose collapses flat when I start the car. It eventually inflates to normal as the engine heats up, but I am concerned I may have a bad thermostat, water pump, etc, and may overheat the engine and do some damage.

The bottom hose is fine at all times as far as I know.

The top hose is a little soft, but I don't think it is just the hose, as it is new. I remember from my youth that radiator hoses used to have springs inside them to stop the collapsing, and I did do some Google research on this. Most posts said that normally the bottom hose is the one with the spring inside it and that is the one that collapses - I could not find any posts about the top hose collapsing like this.

Any ideas what I should be looking for to resolve this issue?

Thanks to all of you who may respond to this - I do appreciate your time.

 

Coolant flow in the Olds motors (and most other engines) is out the top hose, into the radiator, and into the water pump from the bottom hose. When the t-stat is closed, the water pump can create a lower pressure in the radiator, which can collapse the top hose. This may be indicating a bad t-stat, or it may be a weak hose. The fact that it returns to normal shape when the engine is warm tells me that the t-stat is opening, but it may not be opening all the way. You MIGHTASWELL replace both the hose and the t-stat as preventative maintenance.

 

I'd say it's a old hose, new hoses are lot more ridged than the older hoses, I put a new lower hose on my car and noticed it didn't come with a spring inside like they used to, I emailed the manufacturer and they told me because of the newer materials the hoses don't need them anymore. If a bottom hose won't collapse then neither should the top hose.

 

If the hose is not excessively soft, then it sounds like the radiator cap is not allowing air into the system as it cools - instead it is causing a big vacuum.
If the cap is slowly removed when cold, air should enter and the hose expands again.
You might need a new rad cap. Does this car have a coolant bottle? If so, it requires a special kind of cap.