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Alternator clutch sounds like it is departing - safe to drive?


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I'm probably being very thick here, but what is the point of a clutch arragement on the alternator pulley?

 

Every alternator I've ever been involved with has always had a fixed pulley, with the electrical load being controlled by a regulator / rectifier.

 

What actually causes the clutch to engage on these (and presumably drive the alternator) and at what conditions does the alternator not need to be driven?

 

Or is it done for vibration reasons?

 

Confused .....

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It allows the alternator to continue spinning at high speed when the revs drop. During gear changes is a good example, the alternator will maintain speed as the revs change when you change gear.

Otherwise the alternator will be forced to slow rapidly and that's a lot of energy to dissipate.

Sent from my Nexus 4 using Tapatalk

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Oh I see .... so presumably the alternator clutch only allows drive in one direction and "freewheels" in the other, much like the ratchet mechanism on a pedal cycle rear wheel ?

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I've had a similar thing recently, upon starting the car it makes a noise somewhere between rolling a loose ball bearing around a metal tube and sucking on a straw that's half in a drink. The noise subsides somewhat once the engine is warm, sounding more like the rattle of a can of spray paint. The garage have informed me that it's the alternator clutch on it's way out - having it changed tomorrow so hopefully that'll sort it!

Forgot to update this, the new alternator fixed the problem - no more of the described noises

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I still have a slight squeak occasionally which was there before the clutch pulley was changed - I heard this also with the alternator on the bench.  I think it might need a new bearing at some point.

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  • 1 month later...

So I do have this slight squeaking on startup from inside the alternator - a few seconds then it quietens down for the day, until the next morning.  Question is whether it is likely to be dangerous to my motor's health, or is it "liveable" with?  The procedure to swap out the bearings on the alternator looks to be a bit of a pain, so I am probably more likely to replace the alternator.

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I managed to get a genuine TPS Economy alternator on Ebay for £60.  P/N JZW 903 021 RX.  These come without pulley so I took the old alternator out and took off my old pulley.  I have found the really easy way to get the pulley off is to put the hex bolt end of the spline tool in a strong vice, and then use the T50 bit on the end of a breaker bar, supporting the alternator against your body.  The pulley is removed very easily like this, with no possibility of damage to the alternator housing.

 

The new alternator looked absolutely spot-on, however I found when putting the pulley on hand tight that it went on too far and would prevent the alternator rotating.  Got a bit worried and figured the part was probably cheap for a reason, so put the car back together and cursed a bit...

 

Went to look at a "premium" refurb alternator at GSF.  Was a Valeo part, poorly painted, with a no-name refurb pulley on it.  Rubbish.

Went to TPS, the guy got out the same alternator and it looked the same, so was puzzled.

Went to Eurocarparts, their Bosch refurb was fitted with an "INA" pulley whose printed markings (I thought they were engraved) rubbed off.  Though marked INA, it was also obviously a refurbished pulley.

Went home disheartened, and took the car apart again, figure I'd go to TPS and check the pulley on his alternator.

 

Look a little closer.  What is this, a little spacer on the front of the old alternator?  That isn't shown on any of the diagrams, doesn't come with the replacement alternator and isn't shown in the factory book?  Does it just come off with a little prying?  YESSSSS!!!! :)

 

Hope you all enjoy my tale of my own (in)experience...

 

A few piccies for you.

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Finally got round to swapping out the aux belt automatic tensioner today.  Straightforward job, the bit I found hardest was getting the AC belt back on.  I took the top 6mm hex bolt out completely in the end to let me swivel the tensioner all the way up.

 

The old aux tensioner looked minging - I think it had spat some of its fluid out when the alternator pulley went - and is clearly the original VW part (date stamped 2005).  I understand that the service life on these is only really supposed to be 60K, so this was properly on borrowed time.

 

Perhaps useful info for you all; the part fitted to the car originally is the INA unit, just with an extra VW stamp and part number.  I bought my tensioner as the complete pulley plus tensioner unit; total cost £72.84 delivered from CarParts4Less.  INA part number 534 0014 10.  Mister Auto are actually doing it for less than £70 at the moment http://www.mister-auto.co.uk/en/drive-belt-tensioner-pulley/ina-534-0014-10_g310_a204534!0014!10.html , and everyone else's units (SKF, Gates, Dayco) are more expensive! 

 

I think I'll replace the AC tensioner next, I guess that is also of a similar vintage.

Aux belt automatic tensioner

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AC tensioner had quite a bit of play in the bearing, so glad to have swapped it out tonight.  Was also the original INA part.  Swapped for another INA part 531 0309 10, from MisterAuto (£25.33 delivered http://www.mister-auto.co.uk/en/drive-belt-tensioner-pulley/ina-531-0309-10_g310_a204531!0309!10.html ).

Was in a bit of a rush so did it without putting car into service position - just bumper off and dropped the front of the undertray.  Won't be doing that again, the auto transmission fluid lines to the radiator are right in the way of one of the hex fasteners and I kept catching them and getting stuck, while cricking my neck.

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  • 1 month later...

Just wondering if i have the same problem the noise sounds the same but only when sitting,when under load the noise stops. I was told the alternator pulley on way out. Had to drive the car 500miles home no choice. Done the Utube bit but no referance about having to change the alternator.SKF done the utube video. I have no problems on starting and no warning lights relating to this.So i suppose the question is, is the alternator useless or just the pulley and belt tensioner along with the AC pulley plus belt.

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My noise was the same.  In my case my pulley was definitely gone, but when I took it off there was also a small amount of noise in the alternator bearing itself.  To be honest, I could have probably lived with it, but the alternator came up pretty cheap and I am a fussy person, so I swapped it out.

 

If the pulley has been gone for long then the tensioner can have taken a hammering (if you watch the belt and tensioner bouncing when idle and playing with the steering you will see why).  The tensioner is only rated for 60,000 miles anyway by the manufacturer, and I guess yours will be older than that.  I changed the tensioner too, as I didn't want to lose power steering etc if the tensioner collapsed.

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I would also add that some suggestions on the Passat forum were to just get a replacement refurb alternator, so as not to have to bother with the removal of the old pulley, bearing in mind alternator might fail anyhow.  I don't think that is a great idea - all the alternators I looked at in GSF / Eurocarparts were fitted with refurbished pulleys of dubious quality, and the refurb work itself looked pretty variable.  If you can get away with just the pulley it is a winner, but definitely consider the tensioner too.

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  • 2 years later...

hello there

i new here and i hope im writing in right topic

bought a car few weeks  ago and after two days noticed rattling-farting noise from alternator pulley and tensioner bouncing quite a bit.

Put the car in service position and took the belt off. Alternator bearings were gone too not juts pulley so replaced alternator (RTX) with bosch one and tensioner INA

i have read up here about taking fan pulley off or sawing bottom bolt to take alternator off. I didn't do any off that, cos i have few ribs on fan pulley broken so when you undo bolt pull it out as much possible (without ribs extra 1 cm i think) then pries alternator from mounts. As alternator comes off so will the bolt too. If anyone wants too i think ribs can be broken, being aluminium, by pinching with pliers 

and while down there took off intercooler and piping and washed it

i hope this helps someone. 

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