New weird air/liquid leak sound from the engine

[David N.]

Was driving home the long way along an uncompleted freeway, driving mildly spiritedly. I pull into my neighborhood and my CD ends, and I notice a weird sound for the first time. I close my windows (top up), rev the engine a little and realize it's something new, it's coming from the engine compartment, and it's definitely throttle dependent.

It's like a PSSSHHHHT that sustains when the engine is under load. And if I blip it it'll PSHT! sharply, and sometimes again when it returns to idle. It's not the normal little suction sound you get from the outside, because the sound remains when the engine is spinning at 2 or 3k, and mostly because I can hear it from inside the car. I got no CEL, no oil warning, and examining the car afterward I'm not leaking anything. It's not really affecting performance as far as I can tell, although since I've heard the sound I'm in no hurry to really punch it. It sounds like a pipe is spewing something, or an air leak. I'm going to remove the compartment cover tomorrow and check it out before I drive it another foot.

Anyone encountered something like this? Is there a hose or pipe in the intake that commonly springs free or starts to leak?

-David

[CJ_Boxster]

Could be a few things like, bad oil separator, leak in your secondary air injection system, bad air injection valve, Bad electric vaccum pump. Im still hunting down my issue but im living with it for now... I have to buy presents and hold off on the car repair.

With me, it comes and it goes, its never an all day thing and its never an every day thing. I do notice when i hear this Psst noise that its more challenging to change gears smoothly without jerking the car back and forth during shifts.

[David N.]

Thanks for the reply CJ, I feel a bit less worried now.

I took off the engine compartment lid, revved it a bit. Looks like it is definitely an air leak, sounds like it's coming from inside the intake manifold, perhaps around the resonance flap. It's a rushing of air that definitely increases with throttle. It echos around the manifold so I can't really isolate it any more than that.

The guy that was helping me saw the bracketed seals around the manifold center pipes were loose so we tightened those, but didn't affect the air rushing sound. I have no idea how to get any more specific about where the leak is coming from.

Anyone want to venture guesses? Is the resonance flap seal known to go bad? Is that pretty much the only valve in the intake manifold that would be a possibility?

-David

[MNBoxster]

Originally Posted by CJ_Boxster

Could be a few things ... Bad electric vaccum pump...

Hi,

Where's that? Never heard of it?...

Happy Motoring!... Jim'99

[CJ_Boxster]

Hey jim, I'm reffering to the vaccum pump. I take it by ur jerk like responce that the vaccum pump probably isn't run by electricity which is probably what u should have said in the first place....

oh by the way Jim, thanks for the heads up.

[CJ_Boxster]

Did you notice any change in the idle while the hose was whistling?

[David N.]

Yeah, for some reason it went away a day later. I have no idea. I'm guessing the intake got nudged when we tightened the screws, and somehow sealed up again. Or maybe the resonance flap was just sticking for a bit. Maybe pop the top and try tighting the screws on the intake seals, that's all I can think of.

You may also want to check air/oil seperator tho, I hear this can have similar symptoms. Run a search to be sure.

-David