Overheating problem on a 1998 BMW 318ti

Perform a liquid block test (with the bottle of fluid over the radiator mouth.) If the blue liquid turns yellow or clear, you have hydrocarbons entering the cooling system (usually via head gskt.) If not, you have ruled out a costly repair.

Sounds like it overheats pretty easily, without t-stat! This block testing liquid is cheap, and will verify a suspected leaking head gasket without lengthy diagnosis. Hope it's better news, but good luck!

Tater Todd

it's head gasket or water pump, or if you are lucky the thermostat is broken.