I assume you mean your gauge at right of center reads 190, but the only way to tell the actual temp is use a thermometer on it and compare to the gauge .... amount of water shouldn't have any effect, the rad might be low but the block will be full .... try reversing your heater hoses, you may be getting water to the heater from the output of the rad, when it's coolest, rather than from the engine when it's hottest
Bill
