Clattering noise from engine after doing timing belt service
The car has a clattering noise from the engine after doing a routine timing belt service. The shop did the job over and even replaced some of the completely new parts we installed but to no avail. I then took it to the dealership and they did the job again and replaced more already new parts but to no avail. No one knows what this is, can you believe it? I'm hoping someone else with this car has encountered and solved the problem. All the parts were replaced including rollers, tensioners, water pump, everything possible and some of those were replaced again trying to solve this! It sound like a diesel running. You don't notice it at highway speeds but at idle it is load. My other V8 has a tiny bit of that running noise but mostly all you hear with it are the injectors clicking which is normal. It just can't be coincidental that this started with the timing belt service. It doesn't sound like lifters and it's not a cyclical noise like a bearing and one specialist ruled out the cam chain. It's not associated with the serpentine belt, we've run the car with it off and the noise is unaffected. It doesn't affect the driveability of the car, it goes just fine.
It could be so many things that it would be near impossible to diagnose without actually hearing it. Here is a site that helps you diagnose the problem by sound of feel.
http://www.autozone.com/UseCase,S001/UserAction,viewSimpleDiagInfo/Parameters,info/getInTheZone.htm
Dear audiacher,
If you haven't already figured it out, your problem is in the inability of the replacement Stabilus hydraulic tensioner to produce enough force to maintain the correct deflection of the belt. They are all defective, right out of the box. You can put in a new one and check the dimension of the shaft extension and you will find instantly that it is not within spec. That part was also used on the '97 A8, but I spoke to the product manager at Stabilus, and I don't think anyone is going to provide a functional part. If it is any comfort, I have driven mine making the noise you characterize, and at least there has been no failure. If you are really interested, I can give you more info, like the bulletin that gives the shaft extension dimension. Walter@cads.com