My 98' Camry with 335,000 miles is having problems. Dealership says the sound of rocks turning in water is a radiator problem so I had it replaced. The mechanic said the water pump was making the noise so I had it replaced along with the radiator. Now I still hear the sound. My coolant reservoir is filling to the rim, but not going back into the radiator...sometimes the cooling gauge goes way up as if the car is running hot, but it never runs hot. I fill the radiator with water because it is near empty...next thing the reservoir is filled to the rim again. Its as if the water is disappearing somewhere making me think I need to refill the radiator, but where is it going? When I press the gas I still hear the sound of rocks rolling around in water. Why isn't the reservoir emptying itself back into the radiator like it should? I have no leaks.