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I've got an 04 Jetta and it's got a rattling noise at idle. It changes if the rpm is raised, a/c is turned on or steering is turned. I tracked it down to the serpentine belt and the tensioner, it's moving quite a bit. If I put some pressure on the tensioner the noise goes away. I'm planning to do the timing belt next month and will replace the serpentine belt and tensioner at the same time.

Just wondering if anyone else has had this problem?

Tbone
 

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When you have the serpentine belt off, test the alternator pulley... It's supposed to be a "clutched" pulley that free-wheels in one direction... It's very common for these to fail, and one of the tell-tale signs is the shaking of the serpentine tensioner... (They're also known for disintegrating, so better make sure yours is in good shape... they're not too expensive, but you do need special tools to remove them from the alternators... MetalNerd makes a nice set of bits for this - available directly or through his resellers like www.idparts.com or, in Canada, www.roselandtech.com

Yuri
 

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Discussion Starter #3
Thanks I'll check that pulley asap. Can it be changed on engine or will the alternator have to come off?
 

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Metalnerd's latest version of the alternator pulley wrench bits allows for in-vehicle replacement...

(Just make sure you're turning things in the correct direction - many people get confused... the pulley screws on the alternator shaft normally, but because many people turn the shaft rather than the pulley, it appears to be a left-hand thread, which it isn't...)

Yuri
 

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FYI, there is a writeup contest for original pictorials, if you want to take pics of this procedure and show the use of the pulley removal bit, it would really help everyone and also qualify for the contest to win a prize! See the general forum for contest guidelines.
 

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I second the check the alternator pulley comment. I just drove from Ottawa, ON to Charlotte, NC the other week and my alternator pulley came apart in the middle of Virginia. I was lucky enough that there was a VW dealership a couple of miles away. Unfortunately they didn't stock a pulley or an alternator so I had to rent a car to continue my journey.

I was on my way back to pick up the car two days later when I got a call from a service advisor saying that they didn't order the right part so they were scrambling to get an alternator. They ended up putting the alternator on for the quoted price of the pulley install ($232). It took the tech over 2 hours to do the job too. I don't know if he really knew what he was doing.

Anyway, why exactly would one want to have a clutched alternator pulley? It makes no sense to me.
 

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I have a similar problem, the car is fine at idle and only chatters when I steer or when the p/s pump is working, I have changed the alternator pulley and it has had no effect except after I changed the pulley the belt squealed for a bit until the engine warmed up but now it's exactly the same as it was before! I don't know what else it could be, the belt looks fine and the tensioner spins very freely and keeps the belt as tight as it should it just rattles about when the car idles and stabilises when I give it revs but only makes noise when I steer, any ideas?
 

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i have a 06 VW Beetle TDI,
Rattling noise from serpentine belt went away by changing the Alternator ($117)
I cant tell why the old one was making the rattling,
 

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i have a 06 VW Beetle TDI, Rattling noise from serpentine belt went away by changing the Alternator ($117) I cant tell why the old one was making the rattling,
Was it the alternator or simply the one-way pulley? Those are known to go bad...

Yuri
 

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Did you make sure that "lifetime warranty" alternator from Auto-Zone came with a one-way (so-called "clutched") pulley or did it come with a solid, one-piece unit? Many people have found out that they needed to make use of that "lifetime" warranty... occasionally several times...

Yuri
 

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I have just got a 2005 golf 1.9 tdi when u start the car /no lights/no heater/or anything that puts strain on my alternator. But when I load it with lights/steering/heater it starts to make a loud noise?????


Anybody help
 

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Brianrxo - First posts normally go in introductions else you could get a free fix and we never see you again!!!

Forum Rules and Guidelines

Check the fuse box connections on the battery. Check the auxiliary belt and alternator as suggested.

Any problems search TDI Wiki as that covers write ups and forum posts.
 

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Changing the alternator pulley (~$30 + shipping) while mounted on the car is a PITA (IMO) even with the removal tool (~$30) . Depending on how many miles you have on the actual alternator, the actual alternator could go bad soon after the pulley replacement. In my experience a new or rebuilt alternator has lasted anywhere between 60,000 & 90,000 miles (obviously that varies widely). I would definitely check all the pulleys! Serpentine belt failure could - in very unfortunate instances - lead to Timing Belt failure (when serpentine belt or scraps get in the TB path (@ harmonic balancer...). When sliding the serpentine belt off (or putting it on), I would start (or do it last for re-mounting) at the smooth rollers (circled in the picture). And remember to mark the current direction on the old belt if you plan to reuse it.
upload_2019-2-12_9-27-21.png
 

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I have the exact same issue, when putting pressure on the tensioner shock the noise goes away. Did anyone successfully manage to sort their issue out? @Keithuk you've mentioned to check the fuse box connections on the battery, would you mind providing a little more detail on what to look out for? :) I really don't want it to be the alternator as I recently changed the tensioner and serpentine belt and exact same noise persists along with my back pain :D Also could this noise have any serious implications? Alternator seems to be functioning fine, battery starts first time.
 
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