Over heating car

The car over heats. There is not a radiator cap only the cap on the reservoir. When the car is on and starts to heat up, the water in the reservoir starts to rise. After a couple of minutes it starts to spill out of the over fill tube that it has. I have had the radiator flushed and cleaned. I put in a new thermostat. I really don’t now what else it can be. Someone please help!!!

Time for a compression test. Sorry.

Is your radiator fan running while it is overheating ? If it isn’t it could be the fan, fan control module or fan relay. If the fan is running have the radiator pressure tested to show leaks or a blown head gasket or cracked head or block. If it passes the pressure test have someone with a hand held temp. gun check the radiator surface temp. after the car is warmed up to see if there are cool spots that would indicate a clogged radiator. Is your temp.gauge indicating it is overheating ? If you are filling the overflow to the top that will make it overflow. Have your radiator cap pressure tested also, a faulty one will make it overflow.