Chrysler Repair: 1995 Chrysler LHS overheats, 1995 chrysler lhs, head gasket leak

Question
Roland,
My 1995 Chrysler LHS overheats, but not all the time.  I have changed thermostats two times and radiator cap.  I had a new radiator installed about a year and a half ago.  I have recently had the car pressure tested.  I can drive it weeks at a time without it overheating, but then it will overheat.  I check the water level each morning and it is OK.  When it does get hot, I raise the hood to see where all the steam is coming from.  Water comes out of the overflow pipe on the water reservoir causing steam. Two water reservoirs have cracked. The car has 170,000 miles on it.  The water pump was changed when the timing belt was replaced at about 97,000 miles. Can you tell me what the problem is?  

Answer
Hi Rick,
I can't think of anything that would be intermittant the way you describe it. How about the cooling fans? Are they being activated when the temp gauge rises. Why not stop when the gauge appears headed for H and see if the fans have been triggered or not.
The pressure test may check out the radiator and other parts for leaks, but I wonder if you notice any excessive white smoke from the tailpipe which is diagnostic of a head gasket leak. That might be somewhat intermittant if it was just beginning to fail or the torque on one of the cylinder heads was not quite up to snuff.
Is there anything about how the car is being used when it overheats?
How about fault codes: on-off-on-off-on within 5 seconds with the ignition key and leave on. Watch for check engine light to begin flashing, pause, flashing, pause etc. Count the number of flashes before each pause, group the numbers in pairs in the order they came out to form two digit numbers. Repeat the readout to verify accuracy. 12 and 55 are to be expected, anything else is relevant.
You didn't mention which engine but the 3.3 water pump is driven by the external drive belt, while the 3.5 is driven by the timing chain. If you have the 3.3 is the belt tension o.k.? If you can look down the filler cap for the coolant, when the engine has warmed enough to open the thermostat but not really very hot (before it pressurizes) yet you could remove the filler cap and observe whether the coolant is flowing in the engine or radiator as the case may be. This would verify that the water pump impeller is being turned by the drive belt/chain.
Those are the items I would consider. Let me know if anything bearx fruit for you.
Roland