Strange metallic grinding noise when engine in idle: 2006 997 C4
12-05-2011, 06:17 PM
#16
didn't get a chance to update you guys on this matter....didn't get back to it till last night but here are my observations:
- so i ran the engine for a few moments without the belt and the strange noise was not present which was great so it must be one of the accessories as all of you mentioned.
- next I spun each pulley / idler / accessory and nothing popped out of the ordinary in terms of resisting rotation or excessive play/wobbling.
- so i reconnected the belt and started the engine again to diagnose further. Took a really bright lamp and shown it on the fully exposed rotating belt pulley/idlers etc... as the engine was running. What i noticed is that there was a slight wobble (the kind only you would notice if you were to shine intense light on) on the water pump pulley and it synched with this aweful sound. So I went underneath placed my ear relatively near the pump housing which is visually accessible directly beneath the car. The noise definitely was coming from it because when i touched the housing (that's because I didnt have a stethoscope) I felt this vibrating sensation that again, synched up with the aweful noise. I also tried resting the tip of a long screwdriver and placing the back of the handle against my ear and confirmed this grinding vibration. Also tried this trick on the rest of the accessories (alternator, compressor, idler, tensioner..etc...) what I heard were slight and smooth vibrations - 10 folds less intense than with the water pump.
So I ordered a new pump arriving tomorrow morning and a video I found to perform the replacement...stay tuned..
http://www.youtube.com/watch?v=h0L0klF8lVo
- so i ran the engine for a few moments without the belt and the strange noise was not present which was great so it must be one of the accessories as all of you mentioned.
- next I spun each pulley / idler / accessory and nothing popped out of the ordinary in terms of resisting rotation or excessive play/wobbling.
- so i reconnected the belt and started the engine again to diagnose further. Took a really bright lamp and shown it on the fully exposed rotating belt pulley/idlers etc... as the engine was running. What i noticed is that there was a slight wobble (the kind only you would notice if you were to shine intense light on) on the water pump pulley and it synched with this aweful sound. So I went underneath placed my ear relatively near the pump housing which is visually accessible directly beneath the car. The noise definitely was coming from it because when i touched the housing (that's because I didnt have a stethoscope) I felt this vibrating sensation that again, synched up with the aweful noise. I also tried resting the tip of a long screwdriver and placing the back of the handle against my ear and confirmed this grinding vibration. Also tried this trick on the rest of the accessories (alternator, compressor, idler, tensioner..etc...) what I heard were slight and smooth vibrations - 10 folds less intense than with the water pump.
So I ordered a new pump arriving tomorrow morning and a video I found to perform the replacement...stay tuned..
http://www.youtube.com/watch?v=h0L0klF8lVo
