Hi. I’ve replaced the alternator on my 2014 VW Jetta, and all went smooth with the install, except now the tensioner is vibrating and making a noticeable vibrating sound - it wasn’t doing that before. It’s louder and seems more obvious I filmed of it below. I’ve removed and put the belt back on a …

Volkswagen uses double sided belts in some applications, the alternator belt on the 2.5 L engine is double sided.

So, is this a double sided belt?

It would appear so. https://www.rockauto.com/en/moreinfo.php?pk=7134168&cc=3307095&jsn=385&jsn=385 Tester

Hi, thanks for the replies. I just double-checked and there doesn’t seem to be an inside out? There’s 6 female grooves on the pulleys and the belt has 6 male grooves on both sides? Unless I’m missing something? Thanks again! [IMG_4179]

Sorry guys for the delayed reply, I had replied earlier with my above reply but my new account was put on hold while it was reviewed, I couldn’t reply, and it was just now approved. As Nevada_545 and Tester mentioned, it is a double sided belt.

I noticed the tensioner is getting near the end of travel. The belt may need replaced. But I don’t know if that’s the problem.

Learn something every day about two sided belts. But would an out of round alternator pulley cause the tensioner to jump like that? Or is the tensioner getting weak?

Thanks again for the replies. I inspected the belt during the install and it looked fine, but I could try replacing it. One note I forgot to mention is the car is 2014 but only has 15k miles on it. I bought it from an older lady about 2 months ago, it was hers and she stopped driving after a coup…

Just eyeballing the alternator, pulley seems okay, I would go with a new serpentine belt anyway, a 5-6 year old belt is probably becoming brittle. It may not solve your problem, but I consider belt changes as preventative maintenance.

As an idea: when you were removing belt to replace alternator, did you remove the pulley off the tensioner? I know that for Nissan they forbid doing that in their dealer’s repair manual in BIG LETTERS and instruct to replace tensioner with a new part if it was done. The reason for them is that it d…

Tensioner "Vibrating" After Alternator Replacement

Maintenance/Repairs

macfisto February 22, 2019, 4:38am 19

The alternator pulley on my Jeep has a sort of friction slip/one way clutch pulley, supposedly for damping out the pulses from individual cylinders firing. I saw an exaggerated demo video a few years back of what the pulses do to the other equipment driven by the belt if undamped, some component was bouncing all over the place.

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Tensioner "Vibrating" After Alternator Replacement

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