First, thanks to all you guys that replied. I appreciated your suggestions. Still couldn't understand why the benz ran cool, and rad temp was even from top to bottom, as long as i left the cap off the resevoir. Put the cap on and run the car down the road, and the bottom 2/3 of the rad would be cold, and the top hot, then on shut down, coolant would boil out of the overflow hose. Guess what the fix was? I had questioned the water pump. so i pulled it out, and the impeller blade fell off and hit the ground. So, the impeller would turn on the shaft as long as there was no pressure on the cooling system. As soon as i put the cap on, and the system built up pressure, the impeller would just stop spinning. and the pump shaft would spin within it. So, water pump fixed it and my baby is back on the road!!!!!!!