sounds like a clogged heater core may have to be removed and rodded try radiador flush first
The year, make, model and engine info would help. Running todays cars without a thermostat may trip the check engine light to come on. The engine needs to reach and maintain normal operating temperature to run correctly.
the engine will take longer to get to normal operating temp. and the water temp could fluctuate while driving
If the temperature gauge is reading below normal operating temp after driving a little while it may be that your thermostat is stuck open. I replaced my thermostat and it fixed mine.
do you have the right thermostat installed if so is it installed the right way
Sounds like it could be a bad thermostat - not closing to allow engine to heat to normal operating temperature
head gaskets they all do it i have two 99 sts with the same problem cost about 2500 to fix correctly.
Thermostat is stuck open Thermostat is stuck open
If the thermostat in a vehicle sticks open the engine will not reach proper operating temperature. The open thermostat will prevent the car's heater from giving much or any heat during cold winter driving and will also cause the engine to use more fuel than normal.
If this happened immediately after changing the thermostat, then the most likely problem is the thermostat was installed backwards.The spring side of the thermostat faces the engine. It's the spring that is reacting to the coolant temperature and driving the valve to open/close.When the thermostat cannot open, that prevents any coolant from ever getting to the heater core. Thus, you shiver a lot!Pop it out, flip it over and you should be all sorts of warm and cozy.See "Related Questions" below for more
Driving or operating a watercraft under the influence can impact your drivers license.
If this happened immediately after changing the thermostat, then the most likely problem is the thermostat was installed backwards.The spring side of the thermostat faces the engine. It's the spring that is reacting to the coolant temperature and driving the valve to open/close.When the thermostat cannot open, that prevents any coolant from ever getting to the heater core. Thus, you shiver a lot!Pop it out, flip it over and you should be all sorts of warm and cozy.
your thermostat in the cooling system is probably stuck open, you will need to replace your thermostat