GM-GMC: GMC 2005 Safari Problems, universal joints, fastner

Question
Hi, I own a 2005 Safari and it is making a clunking noise when I accelerate in the differential. What is this from, and what can I do to fix it?


Answer
Your description is somewhat vague, however, if you are experiencing noise from the rear of your vehicle during acceration there are a number of possiblities.  One is your differential has internal problems.  This is not something that you will be able to remedy yourself.  One way to determine if you have internal problems is to remove the rear cover from your differential and drain the fluid into a pan.  Have a look at the magnet on the back side of the differential cover, if there are internal problems it it likely going to show evidence here, broken or large pieces will be captured by the magnet.  Another possibility is your universal joints.  They will often clunk or cause a vibration during acceleration.  To inspect them simply remove the four retaining bolts which secure the universals to the pinion, be sure to block the wheels and set the park brake as you will be disconnecting the driveshaft from the transmission.  Use a pry bar to pry the universal joint free from it's housing.  The joint should move relatively freely, it should not feel rough and the small needles inside the caps should not be dry or rusted.  A service manual would be a wise investment if you are going to be undertaking some service and maintenance yourself. It will provide you with proper procudures and fastner tightening specifications.  They can be purchased at most autoparts store.
Hope this helps.