I have a 2000 Blazer LS. About a month ago I had poor heat and a gargling sound in my dash. I knew that the heat was due to the thermostat stuck open so I replaced that. I read that the gargling could be from the radiator cap leaking so I went ahead and replaced that at the same time. It stopped making that noise in my dash up until this past week. It has started back up and it does it when I accelerate. There is no moisture on my floorboard. Does anyone know what this could be? Thank you for any info

 

could possibly be air bubbles flowing through your heater core. I'm not sure where that is on a blazer but just a thought.

 

You have air trapped in your Heater core. open rad cap (when cold) and run car for a while. that should evacuate any air in the system. then fill back up and cap tightly.

 

Ok, thats prob what it is. I did that when I put the new thermostat in. So does air get in there often? Does that mean I have a small leak somewhere letting air in? Thanks again

 

Yes, you probably have a coolant leak. The most common places for leaks are the water pump and the lower intake manifold gaskets.

 

I pick door #2 lastcoupe.

 

I agree with 4lowlife. Mine did that before I did the intake manifold gasket. Do you get little drips of coolant in the floor occationally?

 

It helps if you park with the front as high as possible, uphill for instance...
IĀ“ve heard that air trapped in the heater core might cause leaks as the antifreeze reacts with the air and corrode the aluminium in the core. Not sure if true but better to get rid of the air then having to replace the core [:'(]
/F

 

It is not really the anti-freeze (dexCool) that is the problem. DexCool does not contain any metal protection chemicals that reduce the life of the anti-freeze and so if air is trapped in the system then there is very little protection against rust, and since rust is usually a brownish yellow color like the DexCool the anti-freeze is blamed, but it really is not the anti-freeze's fault primarily. It is just a consequence of the fact that to produce a 100K life anti-freeze they had to remove some of the chemicals that protected the engine metal from the oxidation that is caused by contact with the air...this is the simplistic explanation if you want more go to the Havoline Oil website for more information on DexCool and how it functions...