Afternoon folks. I have a question about my Blazer. I have a '97 and my front right wheel hums all the time when the 4WD is NOT engaged. If I push it into 4HI then the hum goes away, almost like the sprocket isn't getting pulled out all the way and the end of it is grinding the gears. If push it back to 2HI then the hum remains away but will slowly come back. This really started about 2 months ago. I was driving down the highway on a roadtrip changing the volume on the radio when I hit a bump and accidently tapped the 4LO button. Well to my understanding 4HI engages first then waits to do anything with 4LO until you go below 5MPH? There started the faint hum, however it wasn't bad. Then it just gets louder and softer randomly now so if anyone has insight I'd appreciate it. Like I also said, in 4HI there are no noises at all.

Thanks!
Chris Threlkeld
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I would suspect your CV joints are going bad. These connect the half-shafts to the transfer case to give power to the front wheels. Placing the drive in 4HI would put torque on the joints instead of leaving them loose to wabble which would explain why you only have noise in 2WD. Also you might get a clicking noise when you make a hard turn like a front wheel drive car would do when the joints go bad.

The Blazer will not go into 4LO until the car is in neutral and between 0-3 MPH.

 

Yeah I was fearing that. How hard are the CV joints to replace on these trucks?