I am thinking I need new motor, and/or, transmission mounts on my Suburban. Am having popping sounds when I switch from reverse to drive, let off accelerator at speed, and at other times. 1. How can I tell if they are bad? I can visually see the motor mounts, but nothing looks obviously wrong. 2. My Haynes manual says to slightly raise the motor using a block of wood and my jack under the oil pan. Other sites say to never raise the motor under the pan. What is the proper technique?

Any ideas are appreciated.

 

To check your motor mounts your need to use engine torque. Have someone watch (from the side) the engine while you do this: Put the e-brake on and put a foot on the brake. With the 'burb in drive give it some gas. If a mount is broken one side of the engine will raise up. Let up on the gas. Put it in reverse and do the same thing to check the other side. A broken motor mount will likely show other symptoms like a broken fan shroud.

It could be your U-joints too. To test the u-joints have someone bend or lay down alongside the 'burb. With the engine running just shift from neutral to drive, back to neutral and then to reverse. The one observing should hear a clunk if a joint is bad.

 

Sounds more like a u-joint or slop in the rear end to me than a motor mount.