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Lupo TDI making strange noise


marvelt
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I've recently been hearing a noise coming from the car whilst driving so i decided to investigate abit further,

and found that its most prominent from the front offside wheel arch.

I'm thinking alternator belt ?

if you guys could give it a listen and see what you think would be appreciated.

(you can just about hear it over the normal engine idle)

Edited by marvelt
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Yes it is a strange noise. I think it is better to open the bonnet and to find the source of noise with precision because it could be a serious problem. You can use a flexible pipe like a stethoscope (introduce the beginning of the pipe in your ear and you move the pipe end in different zones).

It sound me like a bearing noise. There are bearings in alternator, pulley (on alternator belt or timing belt), clutch or gearbox.Try to make a new film after you open the bonnet and post it here.

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Yes it is a strange noise. I think it is better to open the bonnet and to find the source of noise with precision because it could be a serious problem. You can use a flexible pipe like a stethoscope (introduce the beginning of the pipe in your ear and you move the pipe end in different zones).

It sound me like a bearing noise. There are bearings in alternator, pulley (on alternator belt or timing belt), clutch or gearbox.Try to make a new film after you open the bonnet and post it here.

Does sound like bearing to me too, Need to identify the source - if is timing belt tensioner, then driving with it like it (or running the engine) wouldn't be a good idea...

If the noise is from the offside area, I would suggest removing the alternator belt to see if it stops.

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thanks for the info,

i wouldn't have thought it would be the timing belt tensioner as I've just had the cam belt done with new tensioners and everything,

i opened the bonnet up and it does seem to be coming from the alternator itself, however it is much more audible from the offside wheel arch, without the engine rattling away in your face.

gonna take it in to my local garage this week and see what they think, heres hoping its not expensive.

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Lightly spray WD40 on the alternator belt and see it that stops it.

Alternator belts often make noises like that if they have been removed and refitted, such as when you recently had the cambelt changed.

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thanks for the info,

i wouldn't have thought it would be the timing belt tensioner as I've just had the cam belt done with new tensioners and everything,

i opened the bonnet up and it does seem to be coming from the alternator itself, however it is much more audible from the offside wheel arch, without the engine rattling away in your face.

gonna take it in to my local garage this week and see what they think, heres hoping its not expensive.

Fair enough, although it wouldn't be the first time for a brand new component to go bad.

could try a little lube on the alternator bearings, a small squirt of something like plus gas or WD40 would change the noise and give you the diagnosis.

Personally I would want to be sure of the source of the noise before doing many miles....

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you can just give the bearings a spray - where the shaft meets the casing. at each end. should be ok if you dont go too mad!

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Check if the alternator has a freewheel pulley, or if it has just a plain pulley.

The freewheel pulley has a bearing in it with a spline drive slot in the end. The ordinary pulley is held on with a nut.

The freewheel pulley can seize and throw the pulley and belt off. Mine did this after only a days worth of making a noise.

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The black cover means it is a freewheel pulley.

Here are the two to compare:

AlternatorPulley.jpg

If you gently prod the cooling blades inside the alternator, they should move in one direction with the engine stopped. Otherwise the pulley is seized.

If it is definitely the pulley at fault, I would get it changed asap. When they break they also take out the tensioner. It sometimes confuses people into diagnosing the problem as a broken tensioner. Only to find the new tensioner breaks again in a short time.

Here is my old pulley with the broken bearing, which I found in the undertray:

ShearedPulley.jpg

You need a tool such as the Laser 3307 to fit the new pulley.

I decided to save a few quid in the long run, and bought a new alternator. Unfortunately the one supplied by Bosch came with a standard pulley, so I had to buy a new freewheel pulley from VAG anyway. :rolleyes:

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the cooling blades move freely in one direction, so I'm guessing the pulley isn't seized and is alright,

sprayed some 40 in the alternator bearings, or what i could see to be moving parts,

this seems to have silenced the noise slightly but not cured it.

would it be best to get a new alternator or can you buy the bearings separate?

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Personally I would get an exchange alternator from VAG, if you are sure it's the alternator at fault. They are not mega money.

I also factor in the fact that it costs us on average £20/day to have the Lupo out of action. So in my case the quickest solution can be the best one.

last year I stripped down and priced up all the parts I needed to refresh a Bosch alternator on one of my other cars, and worked out cheaper to get a whole new unit.

First I would whip the belt off and run the engine without it to help confirm the source of the noise. You could then also have a play with alternator pulley directly to make sure.

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The bearings can be replaced. Their codes are: 6303 and 6003. They must be special bearings for alternator, not any bearings. I used FAG and NTN (SKF could be a good choise)

Below is a link to a DYI

http://vwforum.vwfor...showtopic=68329

It isn't a hard operation for somebody with some experience.

You must be very careful because a bearing which is incorrect fitted will have a very short life.

Another interesting DYI

http://vwforum.vwforum.ro/topic/84114-diy-reconditionare-alternator-bosch/

Edited by lupo 1.7sdi
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very impressed by the level of help given on here guys,

much appreciated, I've given it a dose of wd and it has definitely quietened it down, its still there but not noticeable at all over the normal engine rattle.

I'm taking it into the garage on monday, so will get the belt off and have another play try and narrow it done conclusively, will let you know what it was in the end !

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