Hissing Noise
#1
Hissing Noise
I have a 1998 Ford Expedition 4WD, 4.6L Engine. When the engine is shut off there is a hissing noise under the hood. Sounds like air is blowing out through a small hole or pressure is releasing and only last a few seconds. Doesn't happen while engne is running. Noise seems to be coming from the EGR Valve location. Any ideas what this could be?