Overheating problem new radiator cap,

The coolant must operate under pressure to raise its boiling point (so it won't turn to steam.)

Replace the radiator cap with a new one.

you might try a new cap it may be bad

sounds like you may have a blown head gasket or cracked cylinder head.

head gasket is blown

Believe it or not, new thermostats can be bad. Did you maybe get some adhesive on the thermostat preventing it to open fully? Is the thermostat installed with the crown up? The only other thing that I can think of, if it's a closed cooling system and the wrong radiator cap is installed, it won't hold the pressure, therefor overheating. The other thing may be the water pump. Many times the impellers will wear down internally causing to low of water flow.

Assuming you dont have a blown head gasket the most likely thing is a clogged radiator. Lee

I had the same problem, whole new radiator, new hoses, new thermostat, and still overheating. What the problem was for me...bad radiator cap...all that money and a $20 fix...try it?

Have you tried the 8 mm bleeder screw on top of the thermostat housing? You may have air trapped behind your thermostat. Also, overheating can be caused by a collapsed lower radiator hose. If it's soft and you can squeeze it together, then under acceleration it closes down on itself thus preventing the flow of your coolant. Also check your radiator cap. It's supposed to be a 1.1 Bar cap but if it's not functioning correctly, by having to add coolant to the coolant reservoir bottle or the coolant overflow bottle overflowing, usually says it's the radiator cap. These are the simple fixes that you ,may have overlooked.

Good Luck,

~Stillin~

there is a coolant cap on the overflow bottle check it for seal
i'd just replace it
also if you put the new thermostat in backward the overheating would be significant

Cheap try is new radiator cap. If it cant pressurize the system the boil temp lowers considerably. If put new cap on and still over heat could have bad head gasket or a blockage in radiator...Cap is common and 10.00 to fix....