Lupo: Gear/Wheel Bearing Noises - Diagnosis & Repair

I'm attaching my question here.

http://www.dieselschrauber.de/Getriebe_Main.html

My wife owns a Lupo 6X, manufactured in 2000, with a 1.4L TDI AMF engine (currently 197,000 km); it originally came with the EXB gearbox.

I have to admit, I don't really enjoy driving this vehicle, otherwise it would have been more noticeable to me .
After I replaced both wheel bearings, including the wheel hubs, I noticed a new noise.

- If you only accelerate very slightly, it disappears.
- But, as soon as it's just rolling along (in "free wheel" mode, or with the accelerator pedal in a "neutral" position), it sounds like a wheel bearing is running rough.

-is really hard to describe-
The drive shafts have been checked while installed, and so far, I haven't noticed anything that would suggest they are causing the noise. At least for now, the transmission is my prime suspect.

Here's some input regarding the transmission; considering the vehicle's residual value, it's important to keep the costs within a reasonable financial range.

Now I want to disassemble and repair it myself, at least the 020 and 02K models had never given me any problems.

Capacity: 1.9 liters, VW-TN. G 052171A2 = SAE 75W. Is this correct?

Hi,
My first suggestion: start a new thread, otherwise you'll find a real mess of unrelated topics at the end of this one.
Here's the translation:

"The second possibility: why would it be the transmission? You would hear the bearing of the driveshaft better when the car is stationary than when it's moving. You should also be able to hear the driveshaft bearings and the differential when the car is rolling, but with the clutch disengaged. Perhaps you can jack up the car and try to pinpoint the noise while the engine is running. Could it be the springs of the clutch disc?"

Describing sounds with words is always difficult. I experienced a similar effect with the Passat in the signature, for a lifetime.
And without wanting to question your expertise, are things all right with the new wheel bearings?
hg
Herbert.

Hello,

I needlessly bought four new wheel bearings for my wife's A3 because there were noises when rolling. It turned out that the problem was actually the tires, which had become increasingly noisy over time. New summer tires solved the problem immediately.

I spent a long time trying to figure out the problem with the car, and I was actually quite sure it was coming from the wheel bearings. It's also possible that the engine noise during acceleration could be masking other noises, making it seem like they've disappeared... Finding the source of a noise can be really difficult. Therefore, I would first rule out everything else before you disassemble the transmission.

If you jack up the car and "drive" it, and the noises are still there, then it's probably not the tires.

You can upload WAV or MP3 files directly to this forum and they will be playable as files.

What do you think about the idea of a small sensor that can be attached via adhesive, screws, or magnets, and that records both body-borne sound and airborne sound?
With a small button for playback. This could then be placed in different locations within the vehicle, and subsequent test drives could provide clues about the source of the noise.

Best regards, Rainer.

Hello,

I'm familiar with a noise from the 1.4 AMF engine that sounds very similar to your description. However, it occurs when you're not accelerating and not in overrun. It also only happens at a very specific RPM, and I could hear it particularly well in 5th gear, around 60 km/h.
The noise definitely comes from the engine, and you just have to live with it. I've experienced it in both the Arosa and my Polo.

Regards,
Brezelmann.

dieselschrauber wrote:

[...] If you jack up the car and "drive" it, and the noises are still there, then it's likely not the tires. [...]

Correct! Often, people manually rotate the wheels when the vehicle is raised. However, the wheel speeds that can be achieved in this way are far too low to assess the running noises produced by wheel bearings at the usual driving speeds. Therefore, a helpful method for assessment is to have someone lift the vehicle with a helper inside, and have them gently apply the accelerator to reach the previously identified resonance speeds. By walking around the vehicle, you can usually quickly identify the bearing that is causing the noise. From my own experience, this method worked better on front-wheel drive vehicles than on rear-wheel drive vehicles.

It's also worth trying gently pressing the brake pedal while accelerating. On the one hand, this can help rule out whether the noises are coming from the brakes, and on the other hand, it can increase the engine load, which sometimes amplifies the noises. Be careful to keep the steering wheel centered when doing this!

If the noises are coming from the engine or the transmission, the same procedure might also be effective. In this case, the helper should aim for the previously circled speeds and, if necessary, simulate the thrust by abruptly releasing the accelerator. While the effect of the pushing vehicle is missing, it might still be sufficient.

Those looking for a specific sound might have success using a stethoscope, especially if the source is the engine or the transmission. In this case, it's best not to place the stethoscope directly on the metal, but rather to use a firm, multi-layered cloth as a buffer. I've often found the noise level around running engines to be too loud to be able to hear a specific sound amidst all the background noise.

brezelmann01 wrote:

It was particularly noticeable in 5th gear, I mean at approximately 60 km/h.

Generally, at this speed, the noise level emitted by the vehicle should be quite low - wind noise or the increasing noise with increasing engine speed or increasing engine load are not yet very noticeable here.

In addition, I would like to mention the differential of the transmission. It is often excluded as a possible cause, but this is not always correct. Different wear levels, possibly neglected transmission oil changes, rough handling, or a lack of transmission oil can also cause the differential to produce noise.

I don't want to unnecessarily derail this thread.

I had a little more "time" (half an hour) and I looked into it a bit more thoroughly.

The noise (a rattling/grinding sound like a faulty wheel bearing) is not speed-dependent! Instead, it can only be reproduced within a range of approximately 1500-2000 RPM (and is loudest between 1600-1800 RPM), and it is also independent of the gear (although it is most noticeable in the 4th and 5th gears).

And I need to edit my error description from the top.
It doesn't occur during acceleration or when the engine is under load, but only when the accelerator pedal is pressed very gently, resulting in a constant, slow speed.

What surprises me is that this transmission is declared as a 02J. What is the difference between this and a 02J 5-speed transmission, such as the CZL or DQY, used in the Golf 4?


I will follow that suggestion and jack up the front of the car, or if I can get it on a lift, and see what happens. Maybe something will turn up.

P.S.:
Applying both the brake and accelerator pedal simultaneously on a (PD-)TDI engine does not work...

Quote:

Pressing the brake and accelerator pedal simultaneously on a (PD-)TDI engine does not work...

Even with the brake pedal switch and brake pressure sensor disabled...

See my error description. It's normal; you definitely won't find anything wrong. It happened with the ESP transmission and also with the brand new replacement transmission.
Good luck anyway.

dieselschrauber wrote:

You can upload WAV or MP3 files directly to this forum and they will be playable as files.

@brezelmann01:
Okay, at least the transmission shifts smoothly, except for the 3rd gear (it needs a moment to engage when cold), otherwise it's working perfectly.
Say: Wear and tear, and thus play, the rest is taken care of by the "uneven" running of the 3-cylinder engine...

Of course, I can upload MP3 files; it should be manageable even with my Apple device lying in the footwell.

Otherwise - Rainer: I think the idea is good!

It could be a bearing failure in the output shaft bearing. This would definitely not be unusual for a 02J transmission, and it also fits the error description.
"02J transmissions are very good transmissions and can handle a lot of stress, but when something goes wrong with them, it's usually this bearing that fails."

For information:

I can't say with 100% certainty whether it was the cause, but it certainly contributed to it.

- The exhaust pipe's flexible pipe was defective.
- Furthermore, the heat shield on the underbody, in the area of the Oxikat, has detached and was resting on it; this may have caused the resonances inside the vehicle...

- Also, some transmission fluid had leaked out; I had to add about 250ml until it reached the overflow screw. The transmission was completely dry!

Result:
The vehicle was quiet, and I couldn't detect anything else. Furthermore, the shifting difficulties in 3rd gear have disappeared.

However, due to a severely rusted axle carrier (and the holes that were created while attempting to remove the rust - plural -), it was sent for "export"...