505 wagon - listen to it squeak in my short video

H

Hugo

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Melbourne
Hi all

My 505 GTI series 2 1992 wagon squeaks at night!

More precisely when it is cold (less than about 15 degrees C).

I am trying to work out what is causing it.

Check out the squeak in this video:


It only happens when the car is driving which makes it harder to diagnose. After about 10 minutes of driving it goes away. It happens when the engine is above idle, especially when accelerating.

What do you think it is?

I have a few ideas, but I do not want to influence your opinions.

Thanks in advance,
Hugo
 
It sounds in the video like the noise is coming from inside. Speedo cable ?

Coincidentally there is a thread about this right next to this thread.
 
Maybe its in the brakes somewhere??? Just guessing as its hard to tell from that video.

I would try by jacking up each corner and spin each wheel and see if you can hear that noise, will most likely be quieter because you will not be able to turn the wheels as fast as driving.

Another thought is suspension maybe a squeaky bush.

Take someone else with you and say sit them in the back and see if they can locate where that noise is coming from.

Its most likely will be a trail and error exercise until you find it.
 
Hi all

Thanks for your ideas. I'm glad that at least it is not obvious to you all from the recording; that in itself is useful information.

I have a USB microphone that I can attach to my mobile phone to record sounds. I'll try and use it to pinpoint the location of the sound. The main challenge with that is that it is an intermittent fault; I have to wait for cold nights and even then the fault does not always occur and if it does, it does not last long in order to interrogate it, usually about 3 minutes.

I'll also try a process of elimination where possible. Again, the other main limitation to diagnosis is that the car must be driving for the squeak to occur, so no peeking my head in the engine bay! :)

As a matter of pure speculation - the squeak sounds consistent with something rotating and rubbing on something else that is metal. Maybe the rubbing only happens when the engine flexes in its mountings when under some acceleration on the road.

If I work out more I'll post it here.

Cheers
Hugo
 
How about a faulty alternator bearing? Only at night (therefore, with the lights on) could point towards a correlation to current drain.
 
Excellent idea Peter. Yes, alternator bearings are on the list. :)

Another clue - it tends to happen more often when climbing a hill, but not always.

The current list of suspects:
alternator bearings​
power steering pump​
water pump​
the power steering pump drive belt​
the water pump/alternator drive belt​
automatic transmission (hopefully not, due to its complexity and potential expense; but if it is, it is)​
speedo cable​
something else :)​

Hopefully I can eliminate some of these items.

The diagnosis is challenging, but I like a challenge. :)

Cheers
Hugo
 
You almost eliminate any under the bonnet because you said it only happens when driving.

So best places to look are brake rotors/pads, suspension, gearbox, differential.

That is why I suggested jacking up each wheel and spinning it an listen for that squeak, will most likely be faint.
 
Sounds like a drive belt to me. Have a really close look at them and the pulleys. Maybe tighten them up just a tiny bit to see if it disappears.
 
It's pretty much the same sound my harmonic balancer made in my old gti6. Wasn't persistent, just when cold.
 
I would check battery voltage before starting,sounds like normal belt squeal/slip when engine started and battery under load/alternater trying to put charge back in better.how many electrical items are turned on when this occurs?headlights,heater fan,rear Demi steer?.reduce electrical items turned on when started and then see how noise is,but yes check alternator belt condition and tension first..jim
 
lowpugV2 said:
It's pretty much the same sound my harmonic balancer made in my old gti6. Wasn't persistent, just when cold.
Click to expand...
Yes, my harmonic balancer behaved the same. Hearing a difference with the air con switched on or off helped identifying the location.
 
I hadn't considered the harmonic balancer. I'll see if I can confirm it or rule it out with tests if possible.
 
Hugo said:
I hadn't considered the harmonic balancer. I'll see if I can confirm it or rule it out with tests if possible.
Click to expand...
If you can get to the balancer, paint a white line across the full face of the balancer, if the line is broken after you hear the noise you will have your answer.
 
H Pete

Thanks for asking. I'm waiting for some cooler weather here in Melbourne to do some more tests. The squealing most reliably happens on cold nights.

I did mark the harmonic balancer with white paint over all three main components and checked again after some squeaking and the marks were still lined up, so that essentially rules it out. Here are the before and after photos (using a small round mirror to see down to that relatively inaccessible area):

Before:
IMG_20240129 before.jpg


After:
IMG_20240130 after.jpg


As I mentioned before, the primary challenge for diagnosis is the combination of its intermittent nature with the fact that it happens only when the car is driving along (i.e. no looking in the engine bay when the car is in motion sadly :) ).

My main next approach is to use a USB microphone connected to my phone to record the sound levels of the squeaking at different locations, initially in the engine bay, to start to pin down the location of the sound.

Incidentally, I did notice some unusual wear in the alternator pulley which seems to correspond to the belt's reinforcement layer (or whatever it is called). Here is a photo of the pulley wear band and the reinforcement layer that I am referring to:
worn pully annotated.png

...but that is just speculation at the moment. If I can get the squeaking happening and loosen that belt and if that stops the squeaking, then that will help rule it in or out.

I'll post when I have any more info.

Cheers
Hugo
 
You know, I remember my 505 having a strange squeak or two. It was something in the cabin or behind the instrument cluster. Maybe have closer look at that speedo cable... Or there's not a blower motor somewhere under the dash?
 
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