Ford 841

[Sai1997]

I have notice my lower radiator hose claps after running engine. Anyone have reason why this happen?
Thanks
Ken

 

[Larry NCKS]

Thermostat stuck shut

 

[michford]

Could be a bad seal on the radiator cap. Usually the lower radiator hose will have a spring inside it to prevent the hose from collapsing.

 

[sotxbill]

when you run it, the water expands..... in space in the radiator.. when it cools down the water contracts or shrinks as it cools...

so... you bottom hose should have a spring in it to keep the water pump from sucking it close while running.. so if you hose is collapsing CLOSED, you NEED to replace it.

Also.. the correct NEW STYLE radiator cap will have a function to keep a vacuum from forming. This feature also allowed a return tank to catch and return fluid to the radiator....The original cap did not as it was limited pressure but not vacuum. So you could upgrade the cap but try to get a 6 to 7 lb cap, not a more common 13 lb cap used on newer vehicle.

 

[john in la]

Simply put if the lower radiator hose collapses while the engine is running (usually at high RPM's) the water pump is pumping faster than the hose can supply water to it.

The hose could be old and weak causing it to collapse prematurely.
The radiator cap could be sealing the system so well it is creating a vacuum.
Or your radiator core could be clogged.

Try running the engine with the radiator cap loose and see what happens.

 

[Sai1997]

New radiator,new hoses, and new thermostat
I'll have to run it with cap loose

 

[docmirror]

(quoted from post at 19:54:28 10/11/20) New radiator,new hoses, and new thermostat
I'll have to run it with cap loose

This is simple hydraulics. If you are collapsing the hose, then the pump is drawing more GPM than the radiator can flow with the Tstat fully open. Either a restriction in the Tstat, or radiator, or the pump is too big. Since it is not a positive displacement pump(centrifugal vane), most likely a poor or low flow radiator, or the Tstat is too small, or stuck closed.

Did you put the Tstat is upside-down?

 

[RobCons]

Ken if I understand your original post the hose collapses after you warm up the engine and shut the it off. If so it sounds like the radiator cap is not allowing air back into the system as everything cools down. Try running the cap loose. If the hose doesnt collapse get a new cap. Believe it or not I had the top of a radiator collapse because of a gunked up cap. Radiator didnt leak just looked funny.