Mystery engine rattle sound solved
I have a 2000 ZX3 and have had a wierd cyclic rattle from what seemed like the timing cover area for awhile now. It would rattle for about 5 seconds and go away for about 30 seconds and return again in a continous pattern. It seemed like a tensioner or some belt driven component but my stethescope could NOT find it. It even created a slight vibration that could be felt with your hand on the catalytic convertor (before it gets too hot) and on the oil pan. It happened when the AC was off and when I decided to start the ac again recently (its winter and haven't used it in months) it went from a cyclic loud rattle to a quieter grind sound. FINALLY determined its location. Turns out the compressor clutch bearing was going bad AND the three clutch plate rubber bushings were essentially missing and causing a periodic loud rattle that could actually be felt on the OIL PAN! This could have been missdiagnosed as a rod bearing,..it was that loud and sounded similar! New clutch bearing and rubber bushings with a re-finished clutch surface file-job tomorrow will hopefully fix it!