My 2011 Enclave has had 2 motor mount replacements and a new engine in 63k miles. The second motor mount lasted barely a year. I have never replaced a motor mount in 40 years of owning cars. Recently the AC went out. The dealer reported the problem was the high pressure lines to the firewall were rubbing together causing a failure in one of them. Design error? Buick service manager says"stuff breaks". The mechanic could only think of one other time he had seen it in 30 years. I asked if the problem could have been caused when they replaced the engine...Of course not, that is one thing he is completely sure of. The lines were never touched in the removal and reentry of the engine... Whatever. I have seen a lot of posts relating to what is probably broken motor mounts. It is definitely felt when the car is starting in motion. Of course it feels like the engine clunks when you hit the gas-the engine is contacting the frame!!!!!!!!! The head Service manager told me not to worry, because it is not a safety issue-the engine won't fall out!!!! Wow, what a corporate tool. I asked him if he would let his wife drive in a car that is broken like that. Crickets. Maybe if enough people report this issue GM will be forced to fix the actual problem-mounts which are not strong enough to do the job. Any others experiencing these issues?