Gurgling Sound Behind Dash - '02 Malibu, 3.1-L
 

I have an '02 Malibu with a 3.1-L, V-6 and 78,000 miles. I am hearing a gurgling sound coming from under the dash just behind the radio, which I believe is the location of the heater core. I have searched and read several posts with some indicating that the noise is normal, while others have said that the noise is the result of air being trapped in the cooling system. Is such a sound normal or not?


The intake manifold gaskets were recently replaced due to the original OEM gaskets failing, resulting in an internal leak which allowed coolant to enter the engine's crankcase. The engine has always performed flawlessly, both before the intake gaskets were replaced and now. The gurgling sound was present before the gaskets were replaced. I did, however, expect the sound to go away once the intake gaskets were replaced and the coolant leak corrected. Unfortunately, this did not occur.


Could it be that the system was not properly bleed once the work was completed? I do receive plenty of heat when the heater is turned up. My concern is that several of the posts mentioned that any air trapped in the cooling system will cause the DexCool to sludge, thus damaging the cooling system. Not to mention possible cavitation of the water pump.


Any thoughts or suggestions on what may be causing the noise and how to correct it would be appreciated.

Bleed Bleed bleed!
 

Bleed those squeeze hoses and bounce the front end air bubbles can be very stubborn.

the sound is definitely air trapped in the heater core. Be very careful removing heater hoses from a 14 year old heater core. It does not take much force to damage the heater core....and then you wlll have to pull the dash to change the heater core. if possible take the hose off where is connects back to the engine.
vacuum filling can sometimes fix this but if not, you will have to pull a hose