Air Bubble in filler neck. 07 Impala

[Mavigraph]

I've got the 3.5L non-E85 engine. I've noticed that when I take the fill cap off (on the engine, NOT the recovery tank) that the coolant isn't at the top, it's at the bottom of the plasic fill tube ( I can see it when I shine a light down there). When I fill it full and run it for a week or two, it's back at the bottom again and the recovery tank has a little extra fluid in it. My concern is will this air pocket cause the dreaded Dex-cool slug i've read so much about and has anybody else noticed this samething with their impala's?

 

[Chris142]

Sounds like the cap is not allowing it to suck the fluid back into the engine when it cools off.

 

[Mavigraph]

Well, when I look at my recovery tank, when the engine is hot and running, it's fuller than when it cools down. Everytime the engine thermocycles I see the recovery tank respond accordingly.

 

[Cressida]

I am noticing the same thing on my chevy venture. I think bad design by gm but would like to see more views on this. I put on new radiator cap with no change.