TimeOrMoney

I have been trying to fix all the issues in an A6 2.8L I recently bought. 119K miles. Timing belt and tensioner was already done, I did serpentine belt and tensioner(was noisy), and auxilliary fan (also noisy). So I thought I fixed it all, as it was silky smooth on statup. But when it gets warm, it makes noise.

Any ideas? Cam chain tensioner? One of the rollers not replaced with the timing belt?

Rich

audi1031

Try to have another person with you and listen to hear where the noise is coming from. This can be a number of things.

TimeOrMoney

I have, but it's hard to tell.

Kris Hansen

Can you tell at all where the noise comes from? What kind of noise is it? Tapping, creaking, gurgling, rubbing, etc?

Airbag

first thing you need to do as Kris mentioned was determine that type of noise . What i would do is wait till it warmed up and started making the noise , then take off serpentine belt and restert it .. see if noise goes away . then you will at least know what it is ... or what it isn't ..

SloopJohnB@mac.com

Try using a long screwdriver with the handle at your ear and the other end on various places on the motor...don't get near the fan or any other moving part!!!

You should be able to further isolate the noise this way.

jschick

on the 2.8 you have a few areas to check, as said remove the serpentine belt and see if it goes away first.
then you need to check the T-belt tensioner pulley, these actually can come loose after a belt change, so confirm it is good (you can remove the drivers plastic cam cover and look down inside, start the car and make sure the belt runs true and is tight, no flopping around, if the pulley is loose you will see it wobble and the belt flap). then their is the timing chain tensioner. on the drivers bank it in the front of the head and on the passenger bank it is in the rear of the head.

TimeOrMoney

OK, I finally got around to doing the stethoscope on this problem. It's kind of intermittent, and only happens when the oil is at full temperature.

There is a tiny bit of cam chain noise, but not much. The big offender seems like it is in the front of the engine. Maybe the power steering pump? But it doesn't have the sound you would expect from a bad PS pump.

So removing the serpentine belt to test while the engine is hot is good advice, but it would have to be fast, as the sound will disappear in just a short time after the engine is off. (Like walk in a store, come back out, start it and it's gone)

Has anyone just relieved the tension from the belt and started it? Seems like it would work, but I don't want a shredded belt flying all over....

SloopJohnB@mac.com

Try spraying water on the serpentine belt while the noise is there. If it goes away, the problem is a slipping serpentine belt.
Now, why it's slipping is another matter. It could be a bad belt, a contaminated (oiled, or someone's been spraying silicone under there!) belt, or a weak tensioner or another component that gets very hard to turn when hot...

TimeOrMoney

No, read my prior posts. I replaced the tensioner on the accessory belt AND the accessory belt. Tension is good. AND it is NOT that kind of sound. The sound is like something is unlubricated, periodic, like a rubbing sound.

So, to repeat, has anyone just released the tension on the belt for testing purposes?