When cold starting my 1.8T, then you can hear a tick sound from alternator, like metal going against metal. When I raise RPM it goes away and when engine is warm and RPM lowers it goes away. First I saw, that tensioner was jumping and bought new one. Also I bought new battery and get the alternator repaired (new brushes). Putting it back together, again this sound. Alternator went back to repairshop where they changed bearings. Coming home with cheerful thoughts that at least now it should be fine, AGAIN. When pushing tensioner a little bit on the sound will still not stop. Fan bearings are checked and are ok. Could it be the pulley on the alternator? Just don't want to have another go on buying things for no use.

Alternator is Valeo 120A

Could one of the blades on the alternator fan (the component between the drive pulley and the alternator case in the lower photo http://en.wikipedia.org/wiki/Alternator#Automotive_alternators ) be slightly bent and hitting the case? If the repair shop have changed the alternator bearings they should have spotted this but maybe didn't look properly.

They checked it and everything looked normal. When giving some spin with drill manually, no sound. But on car it sounds like brr-brr-brr-br-br-br.

Pulley.

rotodiesel.

Pulley.

rotodiesel.

Even then when the alternator is without clutch?

To the best of my knowledge, all B5.5 alternators have a one way clutch in the pulley. The drive will oscillate without it - destructively.

It's possible that a previous owner has fitted a scrap alternator with a solid pulley, a careful examination should reveal this. The freewheeling pulley has a snap on plastic cap and is locked to the rotor shaft with an internally splined nut under the cap. Solid pulleys are generally fixed with a hex nut and do not have a cap.

rotodiesel.

Edited 4 August, 201114 yr by rotodiesel

In some markets, the alternator has a clutch, so a solid pulley is fitted.

There should always be a clutch. If it's not in the alternator, it's in the pulley - or at least it should be.

Pretty sure the 1.8T pulley is solid, i know it is on transverse engines but easy to tell.

Yes it's solid on mine.

intresting video here on chaneging the freewheel pulley

He's having a laugh taking all the front off the car, it takes 10 minutes tops to remove the alternator if you know how and only 3 bolts iirc.

And 3hrs to put it all back !

On the PD B5.5s the alternator lower bolt fouls the viscous fan clutch impeding removal. There are 2 sensible options:

Using the fan drum holding tool, remove the bolt (8AF hex) from the back of the fan bearing and slide the fan assembly forwards - there is then just enough room to get the alternator bolt out.

My "fix" was to modify the VAG crappy design. When you change the cambelt, the fan bearing has to come out. When this is out, remove the lower alternator bolt and discard it. Replace with a length of M8 studding, a spring washer and a nut. You can then get the alternator out in 5 mins any time. A screwdriver slot in the stud end enables you to hold it.

rotodiesel.

Any chance of a picture roto?

Not necessary - shank of bolt = stud, head of bolt = nut.

Unless you look very hard and know these engines well, it all looks original. But when you need to change the alternator when it fails at the most inconvenient time you can get it off in 5 mins.

rotodiesel.

So problem continues. It's a solid pulley, all bearings are changed. Brushes are changed. They took the alternator apart, centered the shaft and did something with the coil.

When hearing with stetoscope, I can hear the sound coming from the back end of the alternator (where the brushes are). Alternator repairer puts his hands in air and says he doesn't know anything left to do.

Could it be from the pulley being not with clutch, because when trying alternator from 1998 Audi A4, it had the same pulley on it's alternator.