I recently have had the gurgling water noise under the dash and I again replaced my rad cap that for some reason failed again but I still was not getting the air out of the core.
You want to know how to get rid of it, here is the trick.
Have the front of the truck and radiator higher than the heater by using ramps or parking it on a steep hill. This will have the air being forced to the top spot it in the cooling system which is the rad now. Make sure that you have the rad cap side slightly higher as the rest of the rad as well. This will have you getting rid more of the air.
1.) Turn the heat to full and the directional controls to panel or floor. Turn the fan to medium speed.
2.) With a cold engine only, remove the rad cap, start the engine and hold the engine revs at 1500-2000rpms until the engine warms up and the thermostat opens. You will see the coolant quickly drop when the thermostat opens. This is the time to start adding your 50/50 mix of dexcool and distilled water. Add until it is right up to the top and you will see the air bubbles coming up as the coolant displaces the air in the heater core. Continue this for about 10 minutes or until no more air bubbles is coming out. Don't worry if small amounts of coolant is coming out of the rad fill neck, you want that.
When no more air bubbles are being seen or the coolant level is not dropping anymore, install a new stant rad cap and drop the engine back down to idle.
Now, be patient, there might be a little more air in the system for another day or two by right after doing this, take the truck for a god 50 mile run to make sure the coolant is getting everywhere it should be.
since I did this, nothing but slosh-free driving.
Enjoy guys!
