ASZ No Start: Troubleshooting & Repair (Video)

Hello,

I have a problem:

"Our automatic tensioner (ASZ) rattles mechanically when the engine is idling and also when the RPM is reduced. This happens especially after it has been standing for a longer period, like 5 days or more."

It only disappears completely if you drive the car for a few kilometers with the accelerator fully pressed. The problem then goes away, but it comes back if you leave the car standing for a longer period. It's always this "tak tak tak" sound, which is constant and related to the engine speed.

- There's enough oil.
- Whether the clutch was depressed or not.

I made a video, but it's not very clear. I'll make a better one soon, because you can hear it best when the speed decreases.

"Thank you."

http://www.youtube.com/watch?v=atmHjxTf0Tk




Sure, here is the translation of the text from German to English:

"Hello"

I also have a Golf 4 ASZ with a performance chip. It's hard to hear clearly in the video, but I would say that sounds like a dual-mass flywheel issue. Unfortunately, the only thing you can do is remove the transmission and check the flywheel.
Check the alternator's free-wheeling pulley to see if it's locked in one direction and spins freely in the other.

Sounds like a hydro flask.
What kind of oil do you have in it?

wingmaster wrote:

I...but I would say that sounds like a dual-mass flywheel. In that case, there's nothing else you can do but remove the transmission and check the flywheel. .

Please don't be angry with me, but you don't start with the most expensive part... instead, you first check the essential things... as mentioned by the previous poster, things like the type of oil, the oil level, and the hydraulic lifters.

And finally, the ZMS.

hi

Thank you for your replies.

I made another video where you can hear it much better .

The car has Aral Longlife oil in it.

Sure, here is the translation of the text from German to English:

"Hello"

http://www.youtube.com/watch?v=RO6A8Zp2ee4

Octavia_4x4 wrote:

wingmaster wrote: I...but I would say that sounds like a dual-mass flywheel. In that case, there's nothing else you can do but remove the transmission and check the flywheel. . Please don't be angry with me, but you don't start with the most expensive part... instead, you first check the essential things... as mentioned by the previous poster, things like the type of oil, the oil level, and the hydraulic lifters. and finally, the ZMS.

"I deal with cars like this every day, and I've never had any problems with hydraulic lifters in a 1.9 TDI engine, not even after 400,000 km or more in taxis. That's why I simply rule them out."
Whether it's expensive or not, nobody cares. If it's broken, it needs to be replaced. And the dual-mass flywheel (ZMS) often breaks and starts making a rattling noise.

It sounds to me like a knocking, ticking, or tapping sound.
Wenn es im Betrieb warmen zustand weg ist. Is that okay?
My last A4 also had the AWX engine. However, I didn't replace any of the parts.

Yes, exactly, as soon as the engine warms up, it disappears...

I also once had the hood open at that exact time and I immediately noticed that the noise completely stopped.

Why does it only appear after several days of standing, and why isn't it always present when the engine is cold?

"Thank you."

Well, how's the car doing? Is there a way to fix it? I have a BMW that I maintain, and it's always parked on a fairly steep driveway. After being parked for a long time, it develops extreme hydraulic lifter noise.

They can just run out of power.

wingmaster wrote:

I deal with cars like these every day, and I've never had any problems with hydraulic lifters in a 1.9 TDI, not even after 400,000 km or more in taxis. That's why I simply rule them out.

Okay, so...

I also come from the automotive sector, primarily working with VAG vehicles, and I've only had 1 (!!) dual-mass flywheel fail on me so far.

and significantly (!) more problems with rattling injectors! We encountered this issue several times, especially in vehicles with common rail injection systems.

wingmaster wrote:

Whether it's expensive or not, who cares. If it's broken, it needs to be replaced. And the ZMS (Dual Mass Flywheel) often breaks and starts making a rattling noise.

If it's your own money and you have it to spare, it really doesn't matter. But with a customer's vehicle, I wouldn't do that – and I find it borderline to give that advice in a technical forum to someone who clearly has a problem. You shouldn't advise anyone to start with the most expensive part without knowing the full situation.


And "very common" is something I cannot confirm based on my own experience with TDIs (1.9 TDI AHU with 130,000 km, 1.9 TDI ASV with 230,000 km, 1.9 TDI ATD with 225,000 km, 2.5 TDI ACV with 290,000 km), not to mention all the customer vehicles I've worked on. Not a single one of these vehicles has had any issues with the dual-mass flywheel (DMF).



And exactly what Matthias said in the previous post is happening: the hydraulic systems run out of fluid when the car is parked on a hill or for a long time.



And furthermore:

And the ZMS (presumably referring to a component) rattles, especially at certain engine speeds - and in at least one case, it rattles constantly, regardless of whether the engine is warm or cold.


And the statement made by the user who created the thread, confirming that they are experiencing this problem, confirms my assumption that it is not the dual-mass flywheel (ZMS) causing the noise, as the noise disappears when the car warms up.

Okay, and now please explain to me why a faulty (!) dual-mass flywheel (DMF) suddenly runs smoothly when it's warm!

Since I've personally experienced this issue in an extreme case before:

/viewtopic.php?t=21650&highlight=

The idle was very unstable, and at the end, it almost sounded like a metallic knocking/clattering. However, the noise disappeared immediately when the engine speed was increased.

Best regards, Holger.