When i have my truck in 4 wheel hi or low it makes a crunchy grind noise from under the truck. the front axels are not turning. The 4x4 will work in reverse for some reason just not forward doesnt seem to grab. Just wondering if somone can gin a opinion on what they think

 

Does it grind while going in a straight line? Or only in turns. Also what year blazer are we working with? Gotta know if it's the electronic push button or manual lever engagement.

 

Can you be more precise as to where, under the truck, the sound is coming from? And as Jason has already asked, the year will help out as well.

 

its a 97 push button 4x4 it will do this in a straight line or turning if your light on the gas it will stay in but and kind of pressure on the gas and grrrrind reminds me of a dirtbike chain and sprocket with all of the teeth worn off. cant be specific to were th noise is . thanks