Chrysler Repair: heating, chrysler sebring lxi, water pump impeller

Question
I have a 1999 CHRYSLER SEBRING LXI WITH THE 2.5 L the car is over heating we put 2 new thermostats in it.and it is still over heating.the top hose is hot and the bottem is cold.it has been in 2 shop now and they still can't tell me what is wrong with the car.can you help me.thanks harold

Answer
Hi Harold,
My thinking is that the radiator is too plugged up to allow the passage of the coolant thru it, or if that has been checked out and determined to be not the case then I would consider whether the water pump impeller has come loose or been damaged so that it won't effectively pump the coolant thru the system (because that is a costlier repair, I would consider that the last resort). One way to access the flow is to remove a little fluid from the radiator via the drain cock) then start the engine and open the radiator cap before the temp reaches hot enough to pressurize the system and see if the fluid in the radiator appears to be moving (though if the top hose is cold it would not be moving, which is of course the problem, so this test may be redundant).
Another possibility is that there is air trapped in the thermostat housing so that it isn't allowing coolant to pass thru, though that is less likely and the shop manual doesn't give any specific way to refill the system to avoid such a bubble; but while that is being considered, when the thermostat housing is re-opened, make sure that the small "jiggle (vent) valve" of the thermostat was installed so that it was facing directly upward.
Those are the only possibilities I can think of. The radiator blockage is the the conventional explanation, if that hasn't been tested by back flushing it. Replacing the water pump on the 2.5 fortunately is straight forward because it is external to the engine and thus doesn't require any dismantling of the engine the way those pumps that are internal (driven by the timing belt) are on the 2.0 and 2.4 and 3.0L engines.
Let me know which of these hypotheses works out to be correct or some other one I haven't identified.
Roland