Anti Freeze?

A couple nights ago I was driving my car and it sounded like water was running through the dash. I took my car over to the GM dealer and they said I needed to add anti freeze. Since than I have added anti freeze and the sound has gone away for the most part. Does this sound normal, or am I just getting the run around? Also if I put too much anti freeze in my car, there is an over flow valve correct?

that noise is you heater core having air in it, or not being full with anitfreeze. They are right, in that it needs anitfreeze, but the question is, is that where did the antifreeze that was in there go?

Have you ever changed your rad cap?
Do you have any visable leaks(intake gaskets, water pump, hoses, rad)?

Keep an eye on it, and if you havn't changed your rad cap, it would be a good idea.

I went to Advance Auto parts this evening and got a new rad cap. I am going to replace it the morning. I've checked under the car a few times and nothing is leaking. The noise was fine all afternoon until this evening when I went to Advance Auto parts to get the rad cap. I'm hoping that this will fix the problem.

If air is in the heat core how do I get it out after I put on the cap?

You have to purge the air out the system. BlazerLT in the blazer forum has the right idea, this is also how I have always refilled my cooling system. What you have to do is put the truck on an angle with the front higher then the back( I use my car ramps). Now you can do it on a level surface too, but since the heater core is the highest point of the cooling system, it takes a little longer, and maybe a couple of trys to get it all out. Take your cap off start the truck, let it warm up and add coolant as necessay. Once the thermostat opens(takes a couple of minutes), add however more coolant is needed, put the cap back on, and your done. Also refill your overflow tank, to the full hot level too.

Yip, I would fill the overflow tank to the highest you can and just below the overflow tube.

GM recommends this to reduce the coolants exposure to oxygen.

How odd!! I have just gotten mine back from the body shop after pegging a deer. Might I say the work was not that great, but to the point. I noticed the other morning when I started it, I heard what sounded to be water "boiling" or air coming from under the dash on the passenger side. My first thought was heater core going bad, but after inspecting, they replaced my radiator and did not fill it up all the way. Another mark for the body shop. Just thought it was odd that I had this problem and come on here and someone else has the same.. I know I have a simple mind.