Chrysler Repair: 97 concorde overheat, head gasket leak, radiator core

Question
hi Ron, i have a 97 concorde, started overheating today, i
changed the thermostat but that did not solve the problem. when i tried to bleed the system no antifreeze comes out of the bleeder valve, only steam. Seems as if no antifreeze is flowing through the engine, is it the radiator or the water pump? the water pump and timimg belt was replaced 3 months ago. would appreciate your help. by the way, a few months ago i had asked a question regarding no heat, the problem was the heater core had a small leak at the Firewall.thanks
jay

Answer
Hi Jay,
The bleeder valve is on the top of the engine so if the volume of coolant is modestly reduced by loss from some part of the system it would not be surprising to me that only steam came out of the bleeder valve. So I would begin by accessing how low the system is on coolant and if it is a significant volume begin to try and find the leak. I am assuming that the system didn't overheat so much as to blow off steam through the overflow bottle, correct?
So you would want to examine the ground under the vehicle for any sign of a leak, look at the radiator core on both sides as best you can looking for dampness, check hose clamps etc. Then when you have refilled the radiator and bled the system let the car sit for a few hours and when you next start the engine see if you get an unusual amount of white smoke coming from the tail pipe, or notice any bubbling sound from the engine or the radiator. Any of those symptoms are related to a head gasket leak on one of the two cylinder heads and would explain the overheating were they present. The steam from the tailpipe would have an odor of antifreeze if you let it condense on your hand and then smell it.
If that doesn't seem to be the case, then you may have a subtle leak which over the 3 months since the water pump and timing belt were replaced has just left you with a low amount of coolant. There is a method to be followed for refilling the system so as to avoid trapped air which you may already know. But here it is:
On the way to get air out:
It would be good to start with only a partially filled system, so drain off three quarts from the radiator drain.
Then notice that the thermostat housing has a bleed valve and a nipple from which you can drain fluid. Put a 4' length of clear plastic hose on the nipple and direct the hose over the front of the car to a clean container to catch the coolant. Then open the bleed valve. Then slowly fill the coolant recovery bottle until fluid starts to flow out of the clear hose. The gently squeeze on the top radiator hose until all the air is exhausted from the system. Close the bleed valve and fill the system the rest of the way until it reaches the to of the overflow on the bottle. Remove the hose from the bleeder valve nipple.
If that doesn't correct the problem then it would be good to go to a radiator shop and have them attach an exhaust gas detector to the overflow bottle to see if they can identify exhaust gas in the effluent from the bottle. If so, then one of the head gaskets is blown. Another sign of such a leak is white smoke that has an odor of coolant that comes from the exhaust pipe when you first start the car. Of still another is a cloudy or foamy condition of the engine oil as seen on the dipstick. So check those out as well.
On the possibility of the radiator being clogged, that you could assess by comparing the temperature of the two sides (manifolds) of the radiator after the engine has warmed up. If one side is very noticably cooler than the other that  would be an indication of poor flow across the radiator. I doubt that the problem is the water pump because it was just replaced.
So these are my ideas of how to proceed.
Roland