I changed the thermostat and the coolant keeps getting pushed back into the holding tank. The temperature stays cool now, but can't keep coolant in the radiator.
My car has 103000 miles.
My car has an automatic transmission.
Hi, thanks for writing in. This is a sign that you may need to have the radiator system burped. This is a process that is used to relieve the air in the system which can cause the coolant to overflow into the holding tank as you describe. In the event that the car is overheating, this may also cause this kind of problem, but the overheating is a much larger issue that will need to be addressed as well. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect this situation for you, and make or suggest any services or repairs as needed.