Squeling and knocking noise
 

Hey everyone,

Just the other day when I turn on my AC, I heard this really high pitch squeling noise. I think it is the accessory belt or something. it does not make that noise when I start the car and with the AC off. How hard is it to change that belt? can someone show me some pics and instruction? I can't find anything on the DIY forum.

Another thing is the knocking sound coming from the front of the car. I can hear it when the car is moving, fast and slow. Kinda creaking and knocking sound. I've checked all the ball joints and they all look good. all motor mounts are new. Could it be control arm?? or any other bushings? how can I pin point if it is the control arm? it's not the suspension/shocks because it does not make the noise over bumps or turning. Thanks everyone.

RE: Squeling and knocking noise
 

The belt is easy to take off, you see that silver square looking thingy, put a 17mm wrench on it and push it over the tension on the belt will release, pull it off the alternator and replace the belt.

As for the creaking noise, bounce the suspension by hand on the fenders, if you hear any type of squeak or creak its the upper control arm bushings.

RE: Squeling and knocking noise
 

Mine made the same noise after I had changed my TB - I changed my AC tensioner and it fixed the problem

RE: Squeling and knocking noise
 

Are there 2 tensioners? One for the AC and one for the timing belt?? If so, where is the ac belt tensioner located?

Also, where is the upper control arm bushings and what does it look like?

Thanks guys for the replies. Greatly appreciate it.

RE: Squeling and knocking noise
 

What year is your A4? Older 1.8T engines have more than one belt.
The upper control arm bushings are integrated into the links so replacing the upper control arms is what you would have to do to change the busings.

RE: Squeling and knocking noise
 

To see the ac tensioner pulley go down to the bottom of this thread https://www.audiforums.com/m_476929/tm.htm

RE: Squeling and knocking noise
 

I have a 1998 A4 1.8T. I see a couple of belts. How can we be sure that it is the upper control arm and not the the lower ones? if there is any. thanks.

RE: Squeling and knocking noise
 

hey akielb,

the picture of the ac tensioner is exactly what is causing the problem I think because when I went under the car, I can literally turn the pulley on the tensioner with my hands with no effort at all. There is absolutely no tension on the belt!!!! my god. how much is the tensioner?? thanks again.

As for the control arm, auditech79 can you please comment? some pictures would also be great if it's not too much of a trouble. Many thanks.

RE: Squeling and knocking noise
 

well if there was no tension then just loosen up the allen head bolts you see the arrow going to in the pic and apply some downward force and tighten them up again - if that doesn't fix the problem and you want to know where to get the part click the link above the image of the tensioner. - Good luck