Slurping Noise

I recently noticed a slurping noise (similar to when you get to the bottom of a drink when drinking from a straw) when I rev the engine of my 2000 blazer. I only notice it when the rpms get pretty high when revving the engine while in park. I have never heard it while actually driving. It sounds as though the noise is coming from inside the dash on the passenger side, almost as if it is coming from inside the glove compartment.

If anyone has any thoughts as to what could be causing this, and if it is a serious problem, please let me know.

The noise is from air in the coolant running thru the heater core. To remove the air from the cooling system, with the engine hot and running, slightly losen the upper radiator hose clamp. Slip a flat blade screwdriver between the hose and radiator neck until all the air is purged from the cooling system.


Have you checked the coolant level in the radiator (not the overflow tank) when the engine is cold. A trick I use to get the air out of my 2000 Blazer’s cooling system is to drive up on ramps, remove the radiator cap and leave it running. As the engine warms up most the air should work its way out through the radiator. I keep an eye on the radiator and add coolant as needed.

Recently I replaced the radiator on the Blazer and it took a few days of driving to work out all the air pockets. The coolant level in the overflow tank was dropping as coolant was pulled into the cooling system to replace the air pockets. After a few days the coolant level stabilized.

As a precaution, a slowy dropping coolant level could be a sign of an intake gasket leak which Blazers of this vintage are known for. This should be fixed promptly since any coolant that gets into the oil pan will displace the oil from the crankshaft bearings.

Ed B.