That belt looks pretty worn (close to end of life), and the thing you are playing with is an auto tensioner.

You can look it up, here Peugeot (ssg.asia)

 

So the tensioner is failing rather then the belt at this point? The belt was changed in 2017 45k miles ago.

 

Could also be the one way clutch in the alternator pulley has failed if it has one

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Could also be the one way clutch in the alternator pulley has failed if it has one

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Windy, I’ve got a similar noise and a bouncing tensioner even though I have just put in a new one along with the belt and idler. What’s this about a “one way clutch” in the alternator? How do I know if I have one?

I have just put up a post in the 406 forum about exactly this noise.

Thanks.

 

What I see is minor fraying out on the sides, which to me suggests an auto tensioner issue.

Summarise, the wear process:-

1. Over time, belt ribs lose material
2. The space between the ribs increases
3. The pulley sheave will eventually contact the belt valley, causing belt slip to be accelerated.
4. Lastly, is normally like Hydroplaning (like a tire on a wet road) results, but sometimes they skip this and move to break / shred.

This might be useful in diagnostic for the auto tensioner (towards the bottom)
Belt Wear Diagnostic Tips: Diagnose EPDM Serpentine Belt Wear (gates.com)

Gates do make a tool for checking them to decide if they should be changed
Diagnosing EPDM Belt Wear With the Gates Belt Wear Gauge
Serpentine Belt Wear Gauge – Spareco

 

Interesting, thank you. Upon further research that's the auxiliary belt and it's tensioner so replacing the belt itself won't be a problem as it's cheap and it has to come off anyways do replace the faulty tensioner which got way worse after just 1 day of driving so I'll see if there are any other pulleys over there which need replacing as well.

 

Normally the pulley looks different slightly bulkier with a plastic cap on the end.

If you drop the belt off and spin the alternator pulley it should free wheel in one direction.

When it fails you often see the belt whipping and the tensioner jumping around as the inertia of the alternator tightens the belt as it can't free wheel



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Do you mean freewheel in one direction only? Does the clutch engage in the normal rotational direction? Why would they do this?

On mine it still seems to be charging. Is it a whole new alternator if it's faulty?

Thanks for your help. I might have just put in a bunch of parts I don't need.

 

Yes it should drive normally clockwise (standing in front of alternator) and free wheel in the other direction.

Easy test is to spin alternator in each direction and grab the pulley in one direction the pulley will stop the alternator immediately in the othe the pulley will stop but alternator internals will contine to spin

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Yes it should drive normally clockwise (standing in front of alternator) and free wheel in the other direction.

Easy test is to spin alternator in each direction and grab the pulley in one direction the pulley will stop the alternator immediately in the othe the pulley will stop but alternator internals will contine to spin

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Thanks Windy! I went and learned myself up on alternator clutches - didn’t know there was such a thing, never run in to one before. I’m going to check that today.

I see that clutched alternator pulleys are available as a separate part, in your opinion replace just the clutch or entire alternator? Keeping in mind my Pug has almost 370,000kms on it.

Sorry for hijacking your post elgyveeten, but I think we have the same problem.

 

At the milage I would swap the alternator unless you have the tools to change the pulley.

On my old 307 the pulley failed and destroyed a new belt in about 8k miles

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Yes, well, there’s a plastic cap on the front of the alternator pulley and it doesn’t free wheel so I guess there’s my problem. I’ll pull the alternator and see what solution I can find out here in the colonies.

 

I’m going to post this here and on my 406 forum post about the same thing.

I had a noise like elgyveeten show up out of the blue as well. Sounds like a crank pulley I thought. Changed that. Nope. Noticed the drive belt tensioner bouncing around. Changed that. Nope. Saw this post (after posting in 406 forum), windy1603 replies and schools me up on overrunning alternator pulleys. I pull the alternator and shur ‘nuff, it’s seized. I find one out here in the colonies in stock at my local auto electrician for NZ$190 (ouch! but other prices $300 and up!) and get it changed. Put in the alternator and now the belt runs so smooth and quiet!

Thanks windy1603, I’ll know next time!

BTW here’s an excellent video about these things.