I have a 2015 Equinox AWD. In the last couple of days it had started making a Thump, thud or a clunk noise coming from the rear end. It only does it when I drive up a hill. And it's not continuously. Its just a one time thing. Drives perfectly fine on flat roads. There's no vibration. Took it to a shop yesterday to get it checked out since they were the last people to do anything to my car. They did a tire rotation the day before. The mechanic drove it around, he heard the noise but couldn't find anything wrong with the car when he put it on the lift. I worry about driving it around and not having a clue what it could be. Does anyone have any idea what could make a noise like that in the rear that I can get further checked into?

Thank you!

 

I'd jack up the rear end, pull the axle cover off and see whats going on. Could be a bad pinion gear.