new sound under r/s

now a new problem, know that sound of knoby tires coming to a stop? like a whirring? like 2 dry gears coming to a stop? well when in 4-hi it don't exist, but when I run in 2-hi I get that sound when I come to a stop. I raised the front and rear independently tried to simulate the sound by hand (turning the wheels) and by running the truck, but can't get it to make the sound. The only thing I did see is some of the green grease starting to come out of my l/s axle boot (but the boot isn't cut, and there's very little that came out) at the front diff. when I drive I swear the noise comes from the r/s front. Could this be the problem? wouldn't it make noise in 4-hi as well? forgot to mention - it's 97 jimmy. Lt - your opinion?

I also have had this problem with my 97 jimmy
this is what i think it is the 4 wheel lock out is not disengageing
and the gears are turning when you move down the road
I had to put my jimmy in park and go back and forth a couple of times from 2 wheel hi to 4 wheel hi and it disengaged and i no longer have that noise.

ok, I'll give it a shot. I did do the 2hi and 4hi but that was while driving just forward and coming to stop. I'll try it back and forth.

the trucks been sitting in the garage for the last 2 days, so all the parts are at room temperature. I took it out and tried the back and forth 2hi and 4hi thing but it still makes that sound when coming to a stop in 2hi only. I'll try again tomorrow with the parts cold (it's sleeping outside tonight) maybe some parts will shrink in the cold.

well that didn't work, now it won't even go 4x4. I'm taking a break - fustrated. Been reading the blazer forum, alot of info there as well. need to check some things out

ok, got the the thing to go into 4x4 (2hi and 4hi) back and forth no problems. think the humming noise is gone as well, can't really tell, the streets are snow covered and the white stuff squeeks (cold outside). turned out to be a vacuum line to that reservoir thing under the hood (the thing that looks like it's from a toilet bowl), it was just resting on it - not connected. let you folks know more tomorrow if the humming is gone as well.

everythings fine, no more humming and it changes 2hi and 4hi no problems. I don't think the humming was solved because of that vacuum line though. the 4-hi problem yah but not the humming. anyways it's gone. check the vacuum lines and make sure the reservoir is fine.