Sharan 1.9 TDI 4Motion: Loud Rumble When Accelerating?

Hello,

I'm having a problem with my Sharan 4Motion, 1.9 AUY TDI, manufactured in 2006, with approximately 200,000 kilometers on the odometer.
Here's the translation:

"The car starts making a very loud rumbling noise, or rather, it sounds like a sports exhaust inside the car when you accelerate. This is accompanied by a very slight vibration in the front of the vehicle, but it's almost imperceptible, the vibration is so minimal."

According to the mechanic, the Haldex transmission is defective. I personally think the problem lies elsewhere. While driving, I engaged the handbrake one notch to disengage the all-wheel drive, and the noise persists. Therefore, I don't think it's related to the Haldex. Furthermore, the clutch pedal feels quite stiff and also feels strange in some way. That's why I suspect a dual-mass flywheel (DMF). Has anyone experienced these symptoms?

Thank you for your support.

Were the torque-vectoring differentials (Hardy coupling) controlled by the all-wheel drive system? The drivetrain is spinning even though the Haldex system is deactivated.

Yes.

Hardy spacers are in good condition.
"When I stop the car, I can still hear a slight rattling noise. It's normal to some extent due to the transmission, but it sounds a bit more like metal scraping to me."
Upon starting, everything seems normal, and there are no unusual noises again?

It could be the ZMS (torque converter), as my faulty ZMS showed similar symptoms. However, before jumping to that conclusion, it's worth checking simpler things first, like a loose engine cover, as that can also cause significant vibrations.

Before you give up on the Haldex system, it would be a good idea to start with an oil and filter change.

Does the problem disappear if you slightly engage the handbrake while driving (one notch)?

Then the Haldex system will completely fail. And I would personally only suspect the Haldex as a last resort .

Hello,

The noise persists even when I pull the handbrake one notch, which deactivates the Haldex system. Therefore, my suspicion is that nothing is missing from the Haldex unit itself, and the problem might be located elsewhere, possibly in the dual-mass flywheel (ZMS).

"Question: Did your vehicle also make a very loud roaring noise inside when your dual-mass flywheel (DMF) was defective? Otherwise, the car drives completely normally, without any other metallic noises or anything like that. But, as I said, when you stop the car without pressing the clutch pedal, there's still a kind of light, metallic clacking sound?"


The Haldex oil and differential oil changes were always performed meticulously (approximately every 30-40,000 km).

Best regards,

Based on your statements, I can rule out a Haldex defect.

The PD-TDI engine is not inherently a particularly low-vibration engine, and even in good condition, some vibration is present, although it's not extreme droning or rattling. Mine became significantly quieter after the dual-mass flywheel (DMF) was replaced. The slight uneven acceleration and the "clack" sound when accelerating hard also disappeared (which is understandable, considering the DMF could rotate almost 5 teeth internally and had 2mm of axial play).

The metallic rattling sound might indicate a problem with the dual-mass flywheel (DMF), but it's best to get a few more opinions before you tackle the (rather expensive) repair.

Hello,

I would like to announce the solution here:
It was the ZMS (torque converter). It was no longer able to be twisted, so it was locked up. After the repair, the car runs much quieter again, although it's a bit more of a "rumble," similar to a Sharan without all-wheel drive. I think the 4Motion all-wheel drive makes all Sharans a bit more "rumble-y" compared to front-wheel drive Sharans, Galaxys, etc.

Thank you for the feedback!