4.8l, fluid bubbles, sound in the cab

[couchsurf]

2000, 4.8l

hearing bubbles when cold from the heater core area, not at idle but just above idle 1000-1500, sound goes away at higher revs or just cannot be heard. Can be heard if driving or parked. System was flushed 1 year ago by GM. Coolant level is ok, and not changing. Have not tried anything yet cause I'm not sure whats up.

Any thoughts??????

Thanks Duncan

[obbop]

A couple months ago I heard an obvious "gurgling" noise inside the cabin down where I assume the heater core would be.

 

After 5 minutes or so the noise disappeared.

 

Lasted for a couple weeks then went away.

 

Weird.

 

Maybe an air bubble was in the system and "broke loose" and settled near the heater core or sumpthin.

 

I made sure the stealership recorded the complaint.

 

If it returns will tell 'em again.

 

Later this winter will be taking the truck in to sit overnight so that the stealership can check out intermittent problems such as the dash selector for where the hot/cold air is vented: cabin floor or dash outlets / defroster / etc. When cold it sticks and you can not select the outlet. Of course, it IS intermittent and happens when it is cold outside.

 

They BETTER fix it even if they can not replicate the problem since it has happened for two years now. They get ONE more chance before I get mean.