I have a 2004 touran 2.0tdi - tonight there was a intermittent rattle from the timing belt area (under the cover) - the car has done 36000 miles
the rattle / ticking gets worse when the lights are on
thanks
Dt
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This is almost certainly the one way clutch in the alternator pulley giving up (alternator loaded when lights on). Check this carefully, as the parts often make a bid for freedom, with damaging consequences. These wretched things are a frequent source of trouble.
659.
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Thanks for this - My local garage had the same diagnosis - so off to the dealer.
Is it worth doing the cambelt at the same time?
thanks
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These clutches can give trouble on some Renaults as well. Might even be the same alternator given the fact there's quite a bit of BOSCH under my car's bonnet. I was reading somewhere that there's a modified pulley you can fit and be rid of the clutch mechanism.
Another pointless thing in my opinion that never really does much except cause grief further down the line...
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I can assure you that the one way clutch on the alternator drive is not pointless. On a diesel engine, considerable torsional oscillation is present in the auxiliary drive at idle and low speeds. Because the alternator has a particularly high drive ratio on these engines (higher than a petrol engine because the governed maximum speed is lower) these torsionals are magnified in ratio with the drive ratio. Unacceptable driveline and alternator loadings will result unless a one way clutch is fitted - the makers don't fit these for fun.
VW engines nearly always have Valeo alternators - the one way clutches are usually supplied by INA.
659.
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I'm sure my 205 diesel doesn't have one.
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Smaller diesels generally have lower amplitudes of torsional oscillation in their drives - few cylinders with big bangs are the worst offenders. Maybe the designers decided that the oscillations were within acceptable limits on this design - I respect PSA as diesel engine designers greatly, although it's a pity they didn't manage to get the HDi fuel system reliable.
659.
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Thanks for this - My local garage had the same diagnosis - so off to the dealer. Is it worth doing the cambelt at the same time? thanks
Cam belt will be due at 40K anyway from the recent change to the intervals that VW made.
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Surely this alternator problem will be covered under warranty anyway, so you shouldn't end up out of pocket for it. As for having the cambelt changed at the same time, I can't see any point as their will be no price reduction in having it done at the same time.
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IIRC, the alternator is driven by an auxillary belt on these engines. If it is driven by the cambelt, don't put the old one back on, get them to fit a new one. Just don't let them stuff you for the full cost as they have to remove it anyway!
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