Chrysler Repair: Thermostat gasket: 3.8L , radiator cap, temp gauge

Question
QUESTION: Roland,

Hello there, I have a 96 town and country that is blowing cold air from the heater core. The temp gauge is reading lower than normal. I have replaced the thermostat with a fail safe one a few days ago. The problem was corrected for a few days and now its back to cold air and a low temp reading. The radiator was replaced when I rebuilt the tranny about 30K mi ago. I believe the thermostat is stuck open again like the last one. It has never overheated. The radiator cap is about two years old. (It has a pressure relief lever) What is causing the thermostats to go bad?

ANSWER: Hi Micah,
I would not conclude that the thermostat is stuck open, but perhaps you have installed it backwards if that is possible.
Feel the two hoses that go through the firewall to the heater core. They should both be warm, about the same in temperature if you have good flow of coolant through the core.
How hot does the radiator feel after operating at speed for a while? Maybe your gauge is inaccurate and you have poor flow through the core of the heater?
If you write back tell me which engine you have.
Roland

---------- FOLLOW-UP ----------

QUESTION: The engine is a 3.8 and the new thermostat is a Murray from Oriely's. It came with a seal that had a tab on it that did not fit into the thermostat seat, so it was removed and it was installed with a gasket. I have noticed that many after market thermostats have this seal on it with a tab, but they don't fit as the seat for the thermostat doesn't have a place for a tab. I doubt the temp gauge is not working properly as it varies with how hot the air is coming out of the blower. Its possible that thermostat has become dislodged and pushed through the gasket into the goose neck. I am thinking of trying Napa thermostat. Their thermostats do not come with a rubber seal. Do you know if the OEM thermostats from Chrysler have a rubber seal around the thermostat with a tab? I called the local dealer and they do not have any in stock?

Answer
The manual shows only a typical gasket to be used. I don't have any other information, but perhaps the Murray thermostat is not actually sealing the flow around its edge which would be in effect the same as if it were stuck open. I would check out an independent parts store that is aimed at the trade rather than the do-it-yourself community.