I think this is related to the "Sand/marble in the blender" sound. I bought the car just a month ago, it's properly broken in now, and yes it has that sound at HIGH RPM's at WOT. When I bought the car, I remember the coolant tank did not have any bubbles.

Now when I look, there are air bubbles inside the coolant tank. Do I just simply open the cap and idle my engine to let the air bubbles go away?

 

not unless you want your cooling system to be inffective and risk major burns.

Maybe your car is overheating. are you revving it in place a lot?

 

Yes you can do that to remove air bubbles. But the car must be cold before you do this. Let it run until she begins to overheat.

 

if you want to bleed it *better*, park it at some inclined, the head facing UP, let it cool off, open the cap, let it idle until the temp reach 1/2 way, then let it idle for maybe another couple of minutes, shut it off, see if the coolant level stays, if not, top it up a little, close the cap, be happy

 

leaking housing seals on a brand new car???

 

HAY !

It's not a Toyota! No way he would have that problem.

 

I thought only Kia has that problem

 

i noticed the same strange sound at about 6 to 9k RPM at near WOT. sounds like plastic bb's bouncing around in a container (it actually sounds like its coming from the glovebox). it's always done this since i bought it. I think its normal, but I plan to ask the dealer about it when i take it in for my 6k mile service.

I don't think its related to coolant.

 

the sound came from the port opening.

Its normal, but some people found it to be annoying.

Im fine with it, actually I like the *dididididididididididd* sound