I have a 93 150 with a 5.0 in it. I am having a problem with coolant circulation. I have replaced the water pump, thermostat. radiator hoses and the radiator. If I just have the truck idling when it hits a certain temp the upper hose just collapses. When I rev the engine it is pushing fluid past the radiator cap which is also brand new. It does not seem to develop any positive pressure in the system as far as pressure on the upper hose. As far as the hose that comes in just below the radiator cap and goes to the intake it has a full force of coolant through it at all times. Is this normal? Any help will be appreciated.

 

have you bled out the air in the system when you replaced the rad waterpump thermostat? because trapped air will do what your saying and will over heat also

 

I never got to in depth with water pumps on 5.0s but there are reverse flow pumps. I believe 5.0 in cars used them, might want to look into that.