ALH Engine Noises: Serpentine Belt Drive

Has anyone experienced this problem and found a solution? The tensioner for the serpentine belt is vibrating excessively – more so than on other ALH engines. This causes the belt tension to fluctuate, resulting in noises when starting and during steering. The tensioner has already been replaced twice, but the improvement is only temporary; the noises return after a few kilometers. Additionally, the serpentine pulley and a tensioner pulley have been replaced as a test, but there has been no improvement. All pulleys show no excessive play or other abnormalities. However, the engine has 290,000 kilometers on it. Can anyone offer any advice?

Hi,

Are the bearings of the driven auxiliary units in good condition?

Best regards, Rainer.

Hello.

I had the same problem with my 1Z. I had already replaced everything and was about to give up hope, but then a new, thicker belt helped. I bought it from a cheap store (not from VW).

/Jan

Does the Lima have a freewheel?
If it exists, it might be defective; if not, it can be retrofitted. A VW master technician told me that they now do this on many TDIs when there are problems with the timing belt system.
"I drove my alternator (AFN 120A original with one-way clutch) for about a year without the one-way clutch, and then the belt tensioner on the left side became louder than the engine. After installing a new one-way clutch, the noise almost disappeared, but the vibration damper was also no longer functioning correctly. Since I replaced that as well, everything is quiet again. I assume it broke due to the extreme vibrations. However, it was an expensive lesson; the vibration damper cost 260€."

Also, here's something else interesting related to that topic:

http://www.ina.de/inaupdate/news/publics/present/fach_pkw_nebenaggregat/fa_pkw_nebenaggregat_de.asp

Greetings.
dieter

Thank you for the advice. The serpentine belt has already been replaced. I've also considered the alternator's freewheel. I'll try that and then report back on whether it worked.

The change in the free running settings didn't improve anything. Now I'm at a loss. Does anyone have any other ideas?

Have you followed Rainer's suggestion and checked all the bearings, and also carefully inspected whether all the pulleys are running perfectly smoothly?

/Jan

I'm only familiar with the belt tensioners for the 1Z (which are used in AFN and AHU engines) and the ASV (which should also be the same for the ALH engine).

The ASV has a gas-pressure spring damper, which gives a much more robust and solid feel compared to the torsion spring locking mechanism in the 1Z.

http://people.freenet.de/golf-schrauber/Spannrolle/Spannrolle_1Z.html

My 1Z tensioner is so worn out after just one year that you can almost park it in the middle of nowhere because it doesn't apply enough pressure to the belt!

By the way, the AFN bypass kit costs 80 EUR if I want to install it for someone else.

m;

PS: My 1Z became noticeably quieter last year with a new tensioner, and this year with a new belt.

The bearings and pulleys of the auxiliary components are in good condition.