What could cause a car to overheat even after changing the thermostat? Pressure steam and hiss at top of block?

There could be an air pocket in the cooling system if after refilling with coolant the system wasn't properly purged%26gt;
What could cause a car to overheat even after changing the thermostat? Pressure steam and hiss at top of block?
Radiator fan not working. Could be caused by a faulty fan itself or the relay that tells it to turn on when the car is hot. You should also pressure check your system and make sure your cap is sealing properly.
What could cause a car to overheat even after changing the thermostat? Pressure steam and hiss at top of block?
Your cooling fan could be bad. Yoiu might have blockage in the 'water jacket'.

Let the car idle after it is warm and look to see if the fan turns.

Check the fuse for the fan

Always check these first.

Open the radiator cap when the engine is cool. Run the engine until it hits operating temperature and see if the water moves in the radiator.

Try flushing the coolant for the engine. You can buy a kit to do this as most auto part stores.

Don't forget to turn on the heat when yhou are flushing. That will help flush the heater core too.
radiator clogged up, water pump is bad. try flushing out the whole cooling system then see if it,s circulating.