Coolant overflow doesn't drain back to rad.

[austinado16]

I respectfully disagree with that. If there is an overflow tank on a properly operating cooling system there should be no way that an air pocket should be forming in the top of a radiator. I he fills the radiator and the overflow tank it should purge any air out after a few heating and cooling cycles.

Yes, this is how they are designed to work.

@jux, glad you got it. I figured it was the cap since you said there were no leaks.

 

[89Suburban]

Ok, between the new cap and new hose, it is all functioning normally now. Thanks guys. I'm guessing the cap, because it was a bit rusty and the rubber appears to have deteriorated a bit.

Good job, nothing like finding a simple answer to a complex problem.