I have been experiencing a weird engine noise whenever I start my car (05 g35 Sedan). It goes as follows. Whenever the engine is cool and I first start it everything is fine but once I start driving and hit near 2 thousand rpm the engine makes an almost blow off sound and then I hear a rush of fluid near the fire wall area it sounds like. It only happens that one time and then the car runs fine, its almost like something is pinched. And it only happens when the engine is cool. If the engine is warm and I start it and start to drive it doesn't make the sound. Only mod I have on the engine is a stillen z tune and intake. Any ideas??? Ive asked a couple techs around my area and know one has a clue?

 

Mine too. Its an odd sound and I haven't been able to describe it but you seem to have hit it close.

 

me too i would really like to know what that is.

 

Wow, this seems to be a common problem then. If anyone gets their car checked out please keep us posted on what they tell you. I really don't want to spend the $90 to have Infiniti check it out. Any Tech guys have any clues to what may be causing this.

 

That sound you are hearing is most likely coolant running to the heater core. I hear it in mine too and it's nothing to be alarmed about. It only happens once the car is first started. There is no other logical explanation of a "fluid" sound moving around other than rain water collecting and I HIGHLY doubt that. I hope this helps. Or if I'm wrong, I'll stand corrected.

 

Thanks! Is it possible do you think then that maybe there is a line pinched or something and that is what is causing the burst of pressure (blow off sound) in the beginning? I just find it kind of odd that in my case it only happens once the car hits around 2 thousand rpm.

 

The problem is air in your coolant lines. Search "burping coolant" here on the forum and you will find the procedure to fix this.

FYI - Air in the engine cooling system is not good.

 

Not likely. Don't know the ins and outs of the VQ or how and or why it does it. But mine does it at about the same time urs does. An Infiniti tech may be able that question.

 

^^ I have a Nissan service employee in the family....trust me, you have air in your lines.

 

Really? Wouldn't air in the cooling system cause erratic water temp behavior? Ive not once had a problem with temp fluctuation.

 

Not necessarily. It really depends on how much air is in the system. It's quite easy to fix, but takes some patience.

I recently disconnected my upper plenum. If you've done this before you know you have to disconnect the coolant hoses from the throttle body. When I did this, I got some air in my cooling system. When I started the car and started driving I had the same noise/problem. Car ran fine, no erratic temps but the noise bothered me because it never happened before. I simply purged the air from the cooling system and it went away.

 

I bought my car last November and I haven't done any modding to it. Dude u cleared up a question that only sone of us notice. Thanks. I'll double check my system asap

 

Alright thanks for the information! I will look into the forum you posted and try to fix this. I can not stand the noise anymore. Good luck to everyone else with this issue.

 

PAIXAO when I typed in burping coolant I gave me a bunch of threads with people talking about it but not how to get rid of the issue. Do you know a specific thread that has it step by step?

 

I sent you a pm