I just took mine to dealer too, same issue--replaced the water pump and flushed the coolant. They also said there was mud in the heater core and they cleaned that out. They said to do another coolant flush in 2-3 months

 

You should flush the coolant at least every 25,000-30,000 miles, even Dex-cool. In fact ESPECIALLY Dex-Cool.

I was not having heater issues, but I had a leak, and the dealer replaced my water pump too.

 

I have a 2004 special edition Dale Sr #3 Monte Carlo has 35,000 miles on it, bought brand new in 2004. I have been experiencing water noise coming from the dashboard. I took it back to the dealership, they tell me nothing wrong. It just doesn't sound right, and even worse on acceleration. Anyone have any ideas. I do apologize if I have posted this in the wrong place, but this forum is new to me, and this is my first time here. Thank you for any input.
Kitty

 

Check level

 

I too had water sounds sloshing around the dash also a smell of antifreeze from the vents. Then heater core started leaking all over the carpet. I replaced my heater core with one from advanced auto(had to order the part cuz no one had on). No Problems since heat will melt your face off.