i just had a thermostat put in my car?

they either put the thermostat in backwards which I have seen good mechanics do this. (to close to lunch time) or they didnt take the time to bleed the air from the system (to close to quitting time).

While the motor is cold, remove the cap and top off with antifreeze. Turn on the heat all the way to hot, but NOT the fan. start car and let run, get up to operating temp and top off as needed, while running, because it sounds that they have air trapped in it, you will notice while running with the cap off that you probally will get anitfreeze coming out in spurts, dont worry, let it gurgle the air out, just keep topping it off untill you see the thermostat open (you will see the fluid start flowing) and by feeling the top radiator hose. that should get nice and hot. then you know the thermostat is open. then have someone hold the idle up for a few seconds while you top off the antifreeze. cap it and you should be ok.

You have not told us what type of auto this is.

Most newer vehicles have a bleed screw, generally on the thermostat housing or on a heater line that you can bleed the air out that way.

PS:Sounds like a possible air pocket in the cooling system. when the engine is COLD, remove the radiator cap,check the coolant level. It should be above the radiator fins. If not,top off with 50/50 mixture of water and anti-freeze. Replace cap,start engine,let idle until normal temp. is reached. If still overheating,go back to who installed it.

AFTER YOU LET IT COOL DOWN AND REPLACED ANY LOST COOLANT. Good luck.PS: I have seen them installd up-side down! Easier than it sounds.

If it's boiling over...then yes you are overheating....if not then things are OK. If it is now boiling over...then they put in a thermostat that is too high. Find out from the nearest dealer what temp your car uses...then contact the place that put your new one in and ask them what the temp is. If it's too high...have them put in the one that is required.

The OLD one was probably stuck wide open. Now, you are running at the PROPER temperature, which is 195* give or take.

That may look like overheating after the gage was very low before.

check the water antifreez level some times there is a air bubble that works its way out after work on your cooling system

fill it up and your will be ok

check anti freeze to see if its full might of had a air pocket in cooling system

What kind of car is it?