hey, everyone. I'm new to this forum and was hoping i could find an answer here.
I just bought recently a 1988 chevy s-10 blazer, with a 4.3L, and auto tranny. Been working working great through the snow and all, but i am worried about this noise ive been hearing.

It works fine in 2wd and 4x4, but after put into 4x4 and has locked, it makes a whining sound. The sound seems to be coming from the passengers side, but its hard to tell. It gets louder and louder according to the amount of gas you give it. When you let off the gas it becomes faint.

After the truck is fully warmed up, it seem that you have to be going over 40-50km/h in order to hear it. Im just woundering if this is either cause by the diff fluid not being warmed up, or something not greased? I heard that people have this on other vehicles so maybe this could be a noraml sound im hearing coming from the 4x4? I have never owned a 4x4 until now, but I dont regret it. ITS Awesome in snow!

I am the second owner now, and would like to keep this vehicle for a long time, because of the excellent condition its in. It only has 238,000km's on it and it mostly highway travel.

Any suggestions or comments are welcome. I would very much appreciate the help with this since this is my winter ride.
Thanks, rob

 

It could just be the normal "whine" of the front axel Transfer case while engaged.