ALH Vibration? Causes & Solutions - Not ZMS.

Hello. Today, the clutch and flywheel were replaced in my Volkswagen Golf IV.
So far, everything is great. The G60 clutch and flywheel fit perfectly in the Golf. However, the actual problem – the strong vibrations between 2500 and 3000 RPM – has not been resolved. The engine still roars and vibrates loudly, and the vibrations in the gear lever have not decreased either. As I mentioned, it's an ALH engine with 110,000 km on it. The timing belt was replaced 20,000 km ago. It has been tuned with injectors from an ASV (0.205). The power delivery is completely normal. What else could it be? Thank you!

How about the motor mounts? Are they aligned in parallel and is the distance within the specified tolerance?

Could the exhaust system be stressed and/or have holes?

Regards,
Alex.

Hello, thank you for the reply.
I will check the engine mounts and exhaust system again tomorrow.
Are there any other suggestions you have, since I'm already here?

PS: So, the vibrations are quite noticeable. I'm experiencing significant vibrations in the gear lever between 2500 and 3000 RPM.

And what about 184 nozzles?

Possibly, the engine may enter an operating range within this speed band due to improperly calibrated software, which could cause these vibrations. Using original injectors or ASV software might eliminate the vibration .

Regards,
Alex.

Hello. I've actually also considered this issue. The software wasn't adjusted at all. However, I've never heard of such vibrations in connection with larger nozzles. At most, I've heard of a slightly rougher engine running. Also, I drove with these nozzles for about 10,000 km without any problems. But I will definitely take another look at them just to be sure. Thanks, best regards, Bernd.

As I mentioned before, the engine mounts would be a strong candidate.

Perhaps the K-screw as well, although supposedly it shouldn't be a problem anymore with the 038 engines.

Is it quiet in the other speed ranges?

Hello, thank you for the reply.
If you listen very carefully, you can hear that something isn't quite right at almost all engine speeds. However, this is minimal. At 2500 RPM, it starts to get louder, and you can feel vibrations in the gear lever. At 2800 RPM, it reaches its maximum, but by 3000 RPM, it becomes noticeably better again, although not completely normal.

Hello.
"So, the KW screw was checked, and it wasn't the problem. The engine mounts also seem to be okay. Since all of them were loosened, they shouldn't be causing any tension anymore. Finally, a worn pulley was replaced, but that didn't fix it either. I'm starting to run out of ideas. Does anyone have any other suggestions as to why the car is making so much noise/vibration?"

Hello,

How about removing the oil pan and checking the crankshaft assembly? Inspect the connecting rod bearings, piston pins, etc. Use a welding wire to push against the pistons from below while rotating the crankshaft, just to see if there's any play anywhere.

Best regards, Rainer.

Hello, after several frustrating hours, something finally happened.
Since I've seen during extensive online research that there are indeed some people experiencing this problem, I'm writing down what I've found out.

After I even went to VW out of desperation , and they spent a whole morning working on it, I was relieved when they said: "The engine isn't the problem." It wasn't the clutch, it wasn't the dual-mass flywheel, it wasn't the timing belt, and it wasn't the fuel injectors.
The noises stop when you disconnect the shift cables. So, it's either the gearbox or the shift linkage/shift cables/shift mechanism.
Upon closer inspection, we discovered that the counterweight on the shifting mechanism was vibrating extremely in the problematic RPM ranges. The amplitude of the vibrations is so small that it's hard to see, but you can definitely feel it. Initially, we added weight with an iron block. The vibrations disappeared. Since you can't shift with the iron block, I decided to simply cut off the counterweight. I never really knew what that strange thing was supposed to do anyway. And lo and behold: "it works" . The vibrations in the gear lever are 95% gone. Riding is finally fun again!

However, the vibrations that caused the counterweight to oscillate are still present. You can hear them (though not as strong as before, but they are audible), and you can feel them slightly on the gear lever and in the accelerator pedal.
So, the question remains: how can I find out what's causing the problem without immediately replacing the entire transmission?