Strange Noise from AXR - Troubleshooting Guide

Hi everyone!

The problems just keep coming. My Golf IV TDI PD (AXR) has started making a strange noise that sounds like a squeal/hiss. It seems to happen mostly when the engine is cold, and when I'm shifting from 1st to 2nd gear. The noise occurs the moment I press the clutch pedal. As the engine temperature increases, the noise gets quieter until it disappears.

What could be the reason? Perhaps a leak / a faulty spot in the intake system. If so, where should I start looking (ideally with pictures... ). I was at the workshop last week, but they said everything was fine (yeah, right...).

Best regards,
VipViper2000

Hmm, a cold, unused storage space?

Since you normally release the accelerator pedal at the same time as you press the clutch, I'm going to separate these two actions first (meaning I'll keep the engine speed constant) to figure out whether it's the clutch or the accelerator that's causing the issue.

m;

Okay, I'll give it a try and let you know how it goes!

Okay, I was paying attention earlier. It definitely has something to do with releasing the gas. Because he makes the noise even when I'm in second gear and I release the gas without pressing the clutch. Unfortunately, it doesn't make the noise when the car is stationary. So, I can't really tell where it's coming from.

Best regards,
VipViper2000

Hello,

It could also be coming from the timing belt or the timing belt tensioner. If the tensioner is a few days old, or if the belt is too tight, you might hear noises similar to grinding sounds when you release the accelerator. You'll naturally hear it more clearly in the lower gears because the driving noises are quieter at low speeds.

How many kilometers has it been driven?
Has the timing belt ever been replaced?

The noises coming from the belt drive in my case were always dependent on a specific speed, not on releasing the accelerator.
That sounds more like the typical noise of a VTG turbocharger. If you haven't accidentally deactivated the AGR (Exhaust Gas Recirculation) system recently, it might actually be defective, the VTG might be stuck when cold, or there might actually be a leak between the turbocharger and the intake manifold.

Okay, so my Golf IV TDI PD has now reached 58,000 km, and the timing belt hasn't been changed yet. Do you have any tips on how I can check if any hoses might be leaking or simply not properly connected? To be honest, I don't know much about it. Oh, and the car was manufactured in August 2001.

Best regards and thank you for your help.
VipViper2000

Okay, I wanted to revisit this topic because the noise is still present. I've now taken a closer look at the engine compartment and noticed that the area around the AGR valve is oily. I then removed the connecting hose that comes after the mass airflow sensor (MAF) and leads to the engine block, and it was completely oily. Is that normal? And is it also normal for the area around the AGR valve to be oily?

I took some pictures with my phone, but I can't upload them until tonight because I don't have the Bluetooth adapter right now.

Best regards,
VipViper2000

VipViper2000 wrote:

... it was completely oily. Is that normal? And is it normal for it to be oily around the EGR valve?

So, in the AXRs I've seen so far, the connection joints in the air system, located behind the turbo, are all oily. When I received mine, there was even oil dripping from it.
The problem is known in various workshops, but there doesn't seem to be a solution.

Okay, here are the two pictures first:

http://home.arcor.de/vipviper2000/agr-ventil1.jpg
http://home.arcor.de/vipviper2000/agr-ventil2.jpg

I know the pictures are very blurry, but you know what I mean. But where could I look for leaks, if there is one?

Best regards,
VipViper2000

Okay, now that it's getting warmer again, I've noticed something:

'If the car has been sitting outside from morning until noon, and the sun has been beating down on it, it usually happens that when I start it and then drive, the noise completely disappears. Also, the clicking sound at idle goes away. After a while of driving, both the noise and the clicking return. Today, however, it sounded 'normal' from when I left work until I got home.'

It seems like it's getting a little bit better each day. What could it be? I haven't been able to find any leaks so far. Maybe it's a faulty valve?

Please help me!

Best regards,
VIpViper2000