my 95 jimmy will make a whirring noise after I start it and drive a short distance down the road, When I slow down it sounds like the 4wd is engaged but not all the way, If I do engage the 4hi the noise will stop, but when i take it out of 4hi the noise will return a short distance later. If I stop the truck and put it in park and wait a minute or two then put the truck in drive the noise will not return until I turn off the truck and let it sit for awhile like 5 mins to overnight ,then start to drive again the noise will begin again. I was told the vacuum mod port on the transfer case could be bad, but I really dont want to go through the process of elimination if I can avoid this,Does any one have any suggestions as to what may be going on with it.
