do I have to remove the motor to change the timing chain

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! Sounds like your 2013 GMC Terrain is trying to tell you something, and it’s not good. That rattling at startup is often a sign of a loose or stretched timing chain, and now with that pop and the refusal to start, we might be looking at a timing chain that’s finally given up the ghost. The good news? You don’t have to remove the motor to change the timing chain. The bad news? It's still a pretty involved job—like trying to change a belt on a treadmill while it's running. Access to a labor guide or just having a pro handle it will make things a ton easier. Good luck! If you need further advice or want help finding a trusted RepairPal shop in your area, please call us at 877-913-1554!