Air in Cooling System

[MarkRM]

I had the coolant drained and system acid-flushed in my 2000 Sierra with 4.8L about 2 months ago. Ever since, I get this gurgling noise in the center of the dashboard, which I assume is air in the heater core, after the engine gets hot and is shut down and restarted several times (like when doing local errands). The shop has drained and refilled the system again and even purchased a $500 machine to suck coolant and air out of the system and then automatically refill. Still the noise persists. Any ideas what's going on? Is there a surefire way of getting rid of the air? The system is tight - no leaks. I never had the noise until after the coolant drain/flush/refill. Thanks.

[drdd]

Replace the radiator cap. That gurgling noise is air. The cap is not holding pressure. Replace with Stant brand cap or anything NOT ACDelco.

Originally Posted by MarkRM

I had the coolant drained and system acid-flushed in my 2000 Sierra with 4.8L about 2 months ago. Ever since, I get this gurgling noise in the center of the dashboard, which I assume is air in the heater core, after the engine gets hot and is shut down and restarted several times (like when doing local errands). The shop has drained and refilled the system again and even purchased a $500 machine to suck coolant and air out of the system and then automatically refill. Still the noise persists. Any ideas what's going on? Is there a surefire way of getting rid of the air? The system is tight - no leaks. I never had the noise until after the coolant drain/flush/refill. Thanks.

[MarkRM]

Originally Posted by drdd

Replace the radiator cap. That gurgling noise is air. The cap is not holding pressure. Replace with Stant brand cap or anything NOT ACDelco.

I assume you mean the cap on the coolant recovery tank, since the radiator itself doesn't have a cap. Supposedly the shop checked all that out and found everything ok. Is there a trick to getting the air out of the system once it's in there?

[MyTOY]

I have heard people say they jack up the front end and fill and
that got rid of the gurgle. I haven't tried it.

[70camaro]

There is also an issue with a rubber "washer" in the inlet or outlet of the heatercore. Search the site, I know there are posts on this.