Chrysler Repair: 97 LHS engine (3.3/3.5L) running hot, chrysler lhs, upper radiator hose

Question
I have a 97 Chrysler LHS . It ran great for a while and then one day it ran hot. I changed the  thermostat and it didn't help . I even took it back out , just to see if it wouldn't run hot . It appears that the water pump is working. ( not really sure 100 % ). I'm only losing water/coolant when it gets really hot and goes thought the over flow. as far as leaks I don't have any . I don't see any smoke  coming out of the exhaust . The electric fans work fine. could you give me some advice on what to check next. Thanks for your help.

Answer
Hi John,
The car is approaching 10 year of age so I would wonder whether the radiator tubes are narrowed/blocked which might be mitigated by a thorough flush of it. You might compare the temperature of the manifolds on either side of the radiator to see if the temperatures are quite different which would support that possibility.
Other than that, the possibility of air trapped in the system which is decreasing the efficiency of the flow should be considered. I would drain off several quarts of coolant, catching it for reuse. Then notice the bleed valve on the thermostat housing. Attach 4' of 1/4 inch clear hose to the valve so as to route the coolant away from the drive belts when you subsequently open the valve and refill the system via the overflow bottle, placing the hose end into a collecting bottle. Fill until a steady coolant flows from the hose end. Gently squeeze the upper radiator hose to until all air is released from the system. Close the bleed valve. Fill the system to the mark on the overflow bottle.
Remove hose from bleed valve and cap the filler bottle.
If the air bleed doesn't solve the problem then it could be the rediator needs flushing. If that doesn't work then I would consider replacing the water pump. A test of the water pump is to turn on the heater system and determine whether it is working effectively to produce hot air. If not, that would be an indication that the pump in not working effectively.
Roland