Front Drive shaft

tercanb · October 15, 2006

I have a 99 blazer with Autotrac (Auto 4WD, 2HI, 4HI, 4LO) buttons. When the blazer is in 2HI, should the front drive shaft be spinning when I have it up on stands and in gear?

When driving I am getting a grinding, growling, and shuddering within minutes of starting to drive. It feels like something is locking up or grabbing the drivetrain.

What could this be? Transfer case fluid has been changed. Transmission fluid and filter has been changed. Could it be the actuator?, cv joints, u joints, front diff, ?

Thanks for your help.

Wingnut · October 15, 2006

For some reason, I remember this being a topic of hot debate some time ago.

citydriver · October 19, 2006

If I remember correctly, while in "AUTO" the front drive shaft does spin. The transfer case is constantly transfering torque from the rear to the front and back adjusting for traction and driving conditions. I know for a fact that My Dad's Buick Raineir(Buick's TrailBlazer) does this. The whole driveline is controlled by the computer.

I would have the U-joints checked, it doesnt take long and not hard to do.

drumset5994 · October 25, 2006

Yeah, does it on our Jimmy...

I finally realized where the 3-5mpg goes while you drive it.

What would be easy wheeling on a 2wd truck (simply spinning just the hub) on a 4wd, spins just about everything under there.

300Savage · December 7, 2006

Sorry for the late reply. My 01 Sierra did the same thing. I thought it was the front diff. Turns out that even in 2WD the front drive shaft still spins under inertia from the Tcase. My problem was a seized U-joint which prvented the D-shaft from spinning which caused a very slight grinding sound