NHTSA Complaint #11501606 — 2017 GMC SIERRA 1500

Over some time we had noticed a chirping / pulsating sound when starting the engine after it was fully cooled down. Cold start. This sound over the last few months has been increasingly getting worse. We asked our dealer to check things over and determine what could be the issue on a regular service visit for oil change. They could not find a reason but said a service visit with a full line mechanic would be needed to diagnose the issue. We did our own closer look and diagnosing just where the sound and smell of oil fumes or gases were coming from and found the Left side (drivers) rear / back cylinder exhaust manifold bolts to be broken off and gone. There are a total of 5 studs and the rear two had failed and gave away to now allow the exhaust manifold to leak exhaust fumes that are obvious in the cab at startup. This is a pretty major failure and safety problem we feel that GM needs to take action on and correct.