i have a 99 integra ls and the motor is stock w. intake headers and exhaust. my car was on jackstands for 2 days while i do an oil change and various stuff. there was no oil in the motor for about a day (i let it drain all night) i start it up for the first time and a vibrating/whistling noise comes from the header/oil pan/trans area. if i turn the motor off, the noise continues for a few seconds. what the hell is this noise? all the bolts are tight and it drives fine

 

sounds like a vacuum line fell off some where or one may have cracked... try checking all you hoses and lines in that area...

 

that area has nothin but bolts and a few sensors all the vacuum are near the head this sound is like straight above the header and it sounds like a vibration thats like so constant and high pitched that it sounds like a whistle or a squeaking. i have no idea what it could be because other than the flow of air through the motor, everything moving stops as soon as u turn the key off. could it be the oil pump?

 

bump

 

Could be somehow u got a leak in ur header or header gasket, feel around to see if u can feel any axhaust coming out of the header gasket.

 

my bad ls19 it actually was something to do w/ vacuum the pcv on top the valve cover was defective and was creating a whistling/vibration that sounded like it was everywhere, we figured out it was something to do w. pressure kuz when we turned the key off the noise continued yet everything stops except for--AIR weird tho never heard n e thing like it