Cannot be narrow down the clatter
Asked by Nancy Oct 15, 2020 at 10:23 AM about the 1997 GMC Jimmy 4 Dr SLT 4WD SUV
Question type: Maintenance & Repair
Very loud and eventually smooths out some
but at first the sound is very loud clatter or
clanky and it sounds like metal on metal. Has
no power. Also keeps d aiming brand new
battery
2 Answers
Is your check engine light or service engine soon light on? If so, confirm you have a knock sensor code. If you do, replace both. But with the lack of power I'm betting the knock sensors are hearing the engine noise and severely retarding the ignition timing in an attempt to stop the noise. Is the engine running hotter than usual too? That's another symptom of retarded ignition timing. I went through this with my 93 Caprice. It developed a valve tap that the knock sensor was hearing and retarding the ignition problem. Because it was an OBD I system I was able to get around it by disconnecting the knock sensors at the knock sensor module. Don't think you can do that with yours because you have an OBD II system. The engine noise needs to be found and corrected. Hope that helps! Jim
*retarding the ignition TIMING. Sorry! Jim