I have a 99 grand cherokee laredo. 4.0L with selec-trac. 167000 miles. I've had the vehicle for a little over a week. My question is when I go to take off from a stop, occasionally I get what I call a brief whistle and my wife calls a squeal, usually around 16-20 mph, and sometimes it will do it around 30-40mph. Sounds like it's coming from the drivers side of the engine bay, but can't be certain. As far as I can tell, it only happens when the vehicle is cold. And it has been very cold of late, like 10 degree lows. Can't get it to do it while idling or giving it gas while idling. Doesn't sound like a belt squeal, which I'd call a shriek. And belt tension is fine. Very intermittent sound, and lasts all of 1-3 seconds, max. My first thought was a vaccuum related solenoid of some kind making the noise. Thought I'd ask if anyone had encountered such a noise and possible fixes.

 

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