Tensioner rattle

So my 2006 Jetta has been making an increasingly loud “rattle” as of late. I replaced the belt and tensioner recently and that helped for a while then it came back. Looking in the engine while it was idling I noticed what looked like the tensioner (and belt) vibrating a good bit - it seemed that a source of the noise was the tensioner hitting the backstop tab. Turning the AC off reduced but didn’t eliminate it. Now it’s just bad all around and nothing I do improves it. I will also add that when I changed the belt I did inspect the alternator and I could easily turn that pulley with my fingers. Didn’t notice any grinding or wobble.

Any thoughts? Do I need a new AC compressor?


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The symptoms you describe indicate a defective alternator pulley. Search this forum for alternator pulley issues.

"clutched alternator pulley" will probably work pretty well as a search term.

You need this and the tool they sell to change it.
https://www.idparts.com/alternator-pulley-a4a5mk6-p-1118.html

Thanks for the link. Would you also recommend this?

https://www.idparts.com/metalnerd-serrated-alternator-pulley-bit-set-a4a5-p-564.html


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Pretty sure that's the toolset I have... and like all Metalnerd tools it works very well.

Ok thanks. That was weird. When I posted that question about the tool, Idparts website was showing two tool sets as suggested add ons. That’s why I asked - wasn’t sure if I needed both (now realizing I obviously don’t as they are engine specific). I think it was just a glitch and it didn’t process my vehicle selection. Now when I went back it only had the metal nerds one.....

Fingers crossed these $70 will fix it. I’m guessing there are a few YouTube vids out there walking you through it.



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And did I read correctly that all 2006 Jetta TDIs in the US are BRM engine types?


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Yeah, all 2006 jettas are BRM.

So I replaced the pulley and car runs smoother but it turns out that wasn’t the major issue. Apparently my daughter had removed the front driver wheel looking for a nail in the tire and never properly tightened it back on....had lost two lug nuts ? by the time I finally sat in it and drove 10 feet and realized what was going on. Kids....


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Hey there, just checking in with those of you who may have performed this repair...

Were you able to replace the pulley without removing the alternator or getting under the car, as this video suggests is possible? I have a 2010 Jetta TDI MK5 and am hoping to be able to do this repair without getting under the car or jacking it up to access the belt.

Also, I purchased the pulley removal kit and have a 17mm wrench and something to hold the tensioner back when I remove/re-install the serpentine belt.... what other tools would you recommend I have on hand? Thanks!!