4.8is With Hissing Sound

[deanblue9]

Hi Guys,

Of late, my x5 has developed this hissing sound from the left side of the motor on startups. The hissing only occur for about 45 seconds to 1 minute. I dont know if this is weather related because it has been cold in CT. I cleaned the airfilter and checked the air intake system and could find any air leaks. So, last night I removed the engine cover and I could hear the hissing sound from the top left side of the engine. I have searched this forum and gogled but could not find and resolution. Any input and advice would be appreciated.