Andy13186

My car seems to make a hissing noise, randomly, until its warmed up. Im not sure whats causing it but it hisses, then stops for a while then hisses some more then stops and keeps doing this until its warmed up.. My AC is off while it does this and its a pretty quiet hiss, it just sounds wierd and i dont know if its normal, anyone have any ideas?

1999 GT

mine does the same thing..when its warm outside it doesnt do it, but when it's cold out and the motor's cold it does..not all the time, but occasionally

bluepony4.6

Yeah mine does the same thing. I took a mechanic's stethoscope and found that my hissing noise is coming from under my lower intake. Once the car warms up it goes away.

Andy13186

it was louder for me today... no clue why it is happening but it sounds like an air leak

it seemed to happen only under load, accellerating normal in 1st gear u could hear it well, 2nd also but just revving it in neutral didnt make the noise

is this normal? it sounds like a leak but it goes away when the car is warmed up

Andy13186

Today I noticed it only does it after I let the clutch out.. sounds like air leaking for a few secs after sometimes any ideas?


edit - it happens when just sitting there when i start it up now too

1999 GT

anyone?

swarthyfellow

Isn't there a drain plug under the intake manifold... that could be leaking a bit untill in warms up and expanse, which would seal it.

ShadowDrake

The hissing noise is -probably- your IAC. I really noticed that mine became much more pronounced, especially in the cold after I did the IAC restrictor mod. If this is the case, it's no big deal... just the noise of the air moving through it.

Andy13186

that sounds possible - is there anything i could do to tighten it up? i dont have a lift or anything but ill try checking it out


it sounds like its coming from under the car or low in the engine bay, toward the back of the engine