this week I've developed a rattling noise ( like 3 metal nuts being shaken in a tin can) in the front of the engine of my 89 S5 vert.

sounds like its coming from the pulleys . the tensioner pulleys wobble a bit when you pull on the top of them . I tried to tighten the pulley tension bolts and it reduuced the rattle a bit , but then came back ... could it be those bearings making that noise ????

or water pump bearings ?? ... or possibly the Pulsation dampner ?that was mentioned in a thread when I searched

its definately sounds like nuts in can noise that increases with engine rpm .

Car runs fine otherwise ... no idle or power issues , no transmission or clutch issues

WHAT RATTLES LIKE THAT ?

 

It can very well be one of the idler bearings. Remove the pulley and spin it by hand. If it's noisy / not smooth, you need to get a new bearing. Auto parts stores will sell them.

 

You can remove one belt, start it up and listen for noise. Remove the next belt, etc until you've found the source of the noise. My fan clutch made noise suddenly but was easy to replace, so check it also.

 

Is the sound more pronounced when the engine is cold and as the engine warms up the sound either goes away or gets less noticable? If so, suspect the water pump.