dodgy grating metallic noise

[philkef]

intermittent ... aren't they always! and it behaved well when serviced/tested last week ...!

after starting engine and running the car for approx 30 secs - either driving up the road or idling on the driveway, i get a grating metallic whining sound from the front/under the bonnet i assume. it tends to last about 2-4 secs

had brake discs etc checked and they are fine (this was at a time when i thought it was only happening whaen the car was moving .... but since happened on the drive) and the cambelt was changed about 1 year ago so it should not be belt noise.

importantly, it does only make the sound once - when the car is then running, silence and perfection personified! the model child!!

[rotodiesel]

Engine type?

Transmission?

Noise road speed or engine speed dependent?

rotodiesel.

[philkef]

thanks!

1.9tdi tiptronic

road speed would always be less than 20mph - pulling away usually, first couple of hundred yards. alternatively, as i said, it is on the driveway.

[Supurbia]

Sounds like the alternator clutch pulley.

[chappers849]

I agree, thats what mine did :(

[VRSPhil]

Join the club :(

[Supurbia]

Get a recon, new is about £400, a recon varies between £120 and £180 exchange, don't worry about Bosch or Valeo, the only difference is the earth strap mount on the back of it, and both will fit each other.

[VRSPhil]

You can change the pulley on it's own for £60-£100 I thought?

[Supurbia]

You can change the pulley on it's own for £60-£100 I thought?

You can, but if the unit has done over 60k I'd say spend a bit more and get a recon.

[rotodiesel]

Valeo alternators in particular will cover large mileages without trouble - I have an untouched Valeo machine on a PSA vehicle which has covered 150k miles.

The one way pulleys as specified by VAG are rubbish and destined never to be reliable because of the drive torsional oscillations and the high step up ratio. (Remember that rotational stored energy varies as the square of angular velocity so a high drive ratio guarantees trouble).

An alternator should outlast a couple of pulleys at least. Before I got my hands on the special tools, I just took the machine + a new pulley to the local alternator repair shop and asked them to swap the pulleys. Job done in 5 minutes for £5.

All the old Passat problems are coming home to roost on the Superb. Thanks a bunch, VAG.

rotodiesel.

Edited 19 July, 2009 by rotodiesel

[VRSPhil]

Rotodiesel - What are the specific tools? I'm wondering if they're worth buying or if I should just take the whole unit to a specialist...

Thanks

Phil

[rotodiesel]

You need a splined sleeve with spanner flats to engage with the pulley securing ring nut and a long triple-square driver to go through the centre of the whole lot and engage with the end of the rotor, in order to stop it turning.

If you are doing the job as a one off, bribe an alternator repair shop to change the pulley for you.

The correct tools are now both in the tool stores where I work now....

rotodiesel.

[Gizmo]

Do you know if it's the same tool used on both the Valeo and Bosch alternators?

Mine is fitted with a Valeo but most of the tools only say they are for Bosch type alternator pulleys.

[rotodiesel]

To the best of my knowledge, the tool fits both alternators - they both have 17 mm shafts and the INA pulleys are the same. As it happens, the Passat on which I first did this job had a Valeo machine, and my Superb also has a Valeo machine, which means I've never actually tried the tools on a Bosch alternator.

rotodiesel.

[Supurbia]

Hit it with a cold water power washer, try not to get the unit too much just the gap between the pulley and the alt body, it worked on mine until it gave up charging in the end, and it was 30k later it gave up btw.

[rotodiesel]

If you are in any doubt whatever about the alternator pulley condition, change it. There's too much at stake - these pulleys come apart when they fail and the bits go everywhere - fan, radiator etc.

There is also a chance that a flying aux. drive belt will smash the timing belt cover and wreck the engine. Renault know all about this...

These engines are sophisticated - you don't get the power and economy of an AWX diesel with a simple design. Bodging as applied by some, to Ford/GM and other similar products is not a good idea and won't work.

rotodiesel.

[Gizmo]

Well i got a local auto electrician to swap the pulley over today (cost £5).

The metallic rattle i had between 1,800 - 2,200rpm has now disappeared

The bearings inside the old pulley sounded pretty dry and rumbled a bit.