2004 Jeep Grand Cherokee Q&A

2004 Jeep Grand Cherokee Question: high pitched whining noise

this noise comes and goes depending on throttle pressure under heavy load and acceleration it goes away, But under coast or light throttle it has an annoying high pitched whine hard to tell if transmission or rear end -
Answer 1
ck for vac leak at intake manifold -
Comment 1
thing is the 6 cyl engine runs smooth I do not hear a leak when it is just idling and to hear one at 100 klm it would have to be really bad I would think. At a 100klms if I let off on the gas and then apply just a little the whine comes back depending on throttle pressure. -
Answer 2
What about coasting in neutral at 45-50 mph? Rule in/out drive train. -
Comment 1
when I do that it is silent -
Comment 2
Have rear diff. checked/serviced first , then trans. Is it all-wheel drive? -
Comment 3
yes all wheel drive -