OK guys don't flame me too bad for this one.
Ive had my 04 G35 Sport for about 3 weeks now. Love the car and everything about it. Got one question though...
I hear a "sloshing water sound" from behind the dash over the steering wheel when I back out and put it into Drive.
This only happens when I first get in the car and put it in reverse,no other time of the day.

Any ideas on what this could be or where its coming from??

Thanks in advance for any help here.

 

do you get hot air from the A/C when you turn the heat all the way up?

 

could possibly be your abs self test, i guess you could describe the sound as water sloshing around.

 

More than likely you have an air bubble in your coolant line. Try having the car running with the heater on and open the coolant relief valve and let the bubbles come out until it stops. That should fix the problem.

 

Is the coolant jug full? When the car is cold remove the radiator cap and see if the little pressure relief button is stuck. I've seen these stick and allow coolant into the jug but not return and the system get air in it.

 

It could be the brake booster vacuum. It's right behind the driver's side dash in the engine compartment. Mine makes noise every morning right out of my driveway.