One problem related to timing tensioner has been reported for the 2011 GMC Terrain. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2011 GMC Terrain based on all problems reported for the 2011 Terrain.
Motor started knocking louder and louder at 85,000 miles. Brought vehicle to a gm dealer where they replaced; timing chain, balance chain, tensioner, and valves. Gm only claims responsibility for the timing chain, though that part breaking caused far more damage to the motor. Gm has knowingly put and kept out their bad 4-cylinder ecotech motors from 2010-2013. Their class action lawsuit stipulations disqualify most vehicles that are affected. My vehicle is currently broken down due to the same issue, I can't rely on the motor to get me where I'm going without dying at a stop sign or running completely out of oil 2,000 miles after having an oil change. While breaking on a highway my motor will rev up, as if it's trying to accelerate while I'm trying to slow down.