I have what I think is a front diff problem. I was driving the Blazer today and all of the sudden I hear this terrible grinding/humming coming from the front end. Then all of the sudden the tach goes to zero so I thought the truck died. I put it in neutral and tried to start it and it was still running. The speedometer was still sitting at 60 mph, which was the speed I was going when this all happened and none of the other gauges were responding.

So I get the truck off the side of the road, look it over and see nothing out of the ordinary. I start it up, starts fine, shifts fine, etc., but it has the grinding noise like no other when the speed gets over what I am guessing is 5 mph. Don't seem to notice it in reverse at all either.

So my questions are, does this sound like the front diff taking a dump? Why would the gauges stop working? Also, the 4wd does not work either. I am so sick of this thing, when I finally get it fixed I am getting rid of it. Any help is greatly appreciated. Thank you.

 

dont know about your gauges, but the grinding noise could be a wheel bearing. jack it up and check for play and if thats fine than check the front diff oil for metal shavings.

 

Thanks for the suggestion. I know it's not a wheel bearing though. I had just replaced the passenger side wheel bearing and this sound is totally different than when a wheel bearing is going out. I will hopefully be able to get it back to my house today to start checking it over good.