I have a new Rad and cap in the montero 90 v6. The Lower hose colapes after tha car is run some. there is coolent in the resavor and the rad is low every time I look at it. If I open the rad cap it sucks air in to the sys. and the lower hose goes back to normal. I thought the rad resavor is there and that it should suck the coolent back in its like it just pushs in to there and never goes back in to the motor. I Dont think it has been burning the coolent no sign of white smoke for the pipe. seems to run just fine. any Ideas?

1997 Montero LS with a motor swap a 1990 V6 12valve ported heads full 2.5in Ex I run stock tire size for Daily use, off road have 33x12.5 working on going trubo.