shwndh

It seems my 15 months of maintenance free blis is up. I've developed this high pitch squeal or howling noise in the front of my car. I noticed it like two weeks ago but then it went away. It came back today at all engine speeds and at idle, even when first starting. I replaced some leaky vac lines but I didn't think it was related and I still got the noise.

I'm thinking that it's something going bad on the drive belt but I can't seem to think of a way to eliminate components - eveything seems to work fine. I'm hoping it's not the water pump.

Anyone else have similar noise from their 3.0?

diagnosticator1

pulley bearing. It could also be the cooling pump or the power steering pump. Try spraying some water from a spray bottle on the accessory belt with the engine idling, and see if it makes a difference in the squealing sound.

shwndh

TB pulley is potentially catostrophoic - highly. I'll try the trick with the water on the accessory belt, hoping to find something on that belt and not the TB belt. Either way it's going to the shop soon.

Sad part is that my wifes 1.8t is down too. Misfires on all cylinders and engine shaking intermittently. I think it's the O2 sensor on that one. What fun!

diagnosticator1

As far as the 1.8T missfires, it sounds like coilpack problems, not O2 sensor problem. O2 sensor failure generally won't cause random misfires. Coilpacks are easy to replace DIY.

On a diagnostic scan, the misfires will show up, but the coilpacks themselves are not monitored by OBDII, so the misfires are detected via other effected variables.

If it was the O2 sensor/s, there would be a specific O2 sensor DTC/s stored, but the ECU would substitute default values for missing sensor O2 data, and the engine should run without random misfires or roughness.

shwndh

Here's the link.<ul><li><a href="https://forums.audiworld.com/a4/msgs/2769706.phtml">https://forums.audiworld.com/a4/msgs/2769706.phtml</a</li></ul>

Riley's A4

Go ahead and pull out the surp belt for the accessories and then start the car. If you still hear the noise, you know it's something the timing belt is turning. If the noise is gone, then you know it's something the surp belt is turning.

Running the motor at idle, for a few minutes with no belt, won't hurt anything.

shwndh

I don't know. Running the engine without the belt sounds a little scary to me. But it would eliminate parts driven by that belt.

Riley's A4

while you are listening for the noise you described.

The water pump is not driven by the surp belt, the battery has more than enough power to run an idling motor and since you are not moving he vehicle, the power steering unit is not needed.

Might also be a good time to replace the belt, if it hasn't been done within the past 30k miles.

A4AdMan

from the right front of my 3.0 three years ago. It ended being a electric cooling fan motor replaced under warranty at 44K miles.

shwndh

Thanx. I'll look into that. The noise has been gone since I posted this though