Ok, I've got the battery light on and the Alternator Workshop message up, I think it's the alternator because there's plenty of battery and I thought I heard a knocking sound recently coming from that general area.

So, I've had a look and I can see the two bolts holding it and can get spanners on both, but I see there could be a problem getting the bolts out because of distance to the fan, also do I need to slacken the tensioner wheel or can I get away with doing the lower bolt up and levering the new Alternator back to go get the top bolt back in, if I do have to release something does anyone know what it is?

To say I'm miffed is an understatement, I was getting rid off it and I wouldn't have another bill to find for.

The Valeo alternators fitted are reliable but the INA one way drive clutch in the pulley is not. Check that the alternator is actually being properly driven before you condem it.

With a stationary engine, put a small screwdriver into the front of the alternator behind the pulley and engage the internal fan blades. The rotor should turn clockwise easily and be solid in the other direction. Take great care not to damage the stator windings.

rotodiesel.

I think it's gone tbh, the battery seems to hold a charge ok and I think the unit may even still be charging the battery, but it's chucked the warning lights on, I've had the plug off and cleaned the earth up but that's made no difference, I thought I could smell something a few days ago, and that and the dead of night knocking I could hear, well knocking or tapping anyway suggests it's done it's day, any advice on how to get it off, potential problems?

I've swapped the battery over with a spare and it's still happening, had a run down the road and the autobox wasn't as smooth returning to 1st at junctions as it normally is, I'm assuming this could be related as although Diesel engines will run without electric the rest of the electronics need stable voltage, had a look at the clutch Roto and all seems to be spinning inside the unit in sync with the pulley wheel, it's 120 notes +vat for a non gen one, I'll call VW for a mega quote in the morning, but I think the price will be much higher.

Edited 16 April, 200917 yr by Supurbia

Ok I found an old thread on it, I'm going to try to do a how 2 on it tomorrow, so far I've had a look at the nuts and bolts and I don't see anything that should scare me.

This is a thought process guide for now incase I don't get time to picture it.

Tools

1 - 10mm spanner for undoing the negative terminal

1 - 3/4 Spanner for leaning on the tensioner with

1 - 8mm allen key for undoing the viscous fan bolt

1 - 13mm spanner for undoing the alt bolts and for undoing the earth wire

1 - small flat blade screwdriver for unclipping the alt lead

Ok, here's how I intend to do it,

1 - Undo the 10mm battery - terminal

2 - Draw a diagram of how the belt runs

3 - Slacken the 8mm fan bolt

4 - Untension the belt with 3/4 spanner, leaning it towards the drivers side of the car

5 - Slacken the 13mm alt bolts

6 - Remove 8mm fan bolt and drop fan into fan housing

7 - Remove loom and earth wires

8 - Remove 13mm alt bolts and take off alternator

9 - Refit in reverse.

Hth someone in future

The fan spindle bolt is tight. There are two holes in the fan drive drum to take a VAG holding tool, otherwise you can hold it by overtightening the drive belt with the "3/4" (it's 19 AF) spanner on the drive belt tensioner, used in the "wrong" direction.

Last time I took the alternator off a Passat I just cut the head off the long alternator mounting bolt and replaced it with studding and a nut. It makes the job easier next time.

If your alternator really is faulty, try to find the fault - in my experience the Valeo machines are reliable, Bosch less so.

rotodiesel.

I'm going to try the pulley test in a min, price seems to have risen overnight sadly, and I've got to order it, are the pulleys reasonable in price do you know, and is the tool for locking it an expensive option?

Fixed it, got a new unit this morning, I checked the old one and the pulley was still engaging ok so it's obviously had another part failing in it, all went pretty well, I didn't have time to picture it in progress, but it is easier to undo the fan than destroy the bolt, simply leaning the other way on the tensioner allows you to undo the bolt, although it does take a bit of effort to get it to move to start with, I put a recon unit in, cost me 137 inc vat exchange, so that was better than the 200 I was quoted earlier, not a hard job to do, little bit awkward at times but all in all a result.

I found swarf under the unit when I took it off, so I think something was probably worn out completely inside.

Edited 17 April, 200917 yr by Supurbia

Ok, whats the difference between an 04 and an 04 Alternator ?

When I was shopping around there seemed to be some confusion as to which unit was which, tonight as you've probably guessed the recon unit has failed, all started off about an hour after I went to work with a warning light that went back off as I backed off, then I found I could get it on at any time by reving the car to 3000 rpm on idle, then as I was about to pull away it's on all the time again, looking at the unit the numbers were the same but mine had some 15/04 on it the new one has 35/02, anyway I came home and started to double check for secure bolts and belts, all fine, but when I switch off there is a whining sound for a few seconds after, so I think I've been sold the wrong unit and the sound could be the pulley clutch, but it sounds after the pulley and belt has stopped, any advice?

Does anyone know if a fully functional but dying battery can cause the battery light to come on even if the battery isn't discharged, i.e a dying cell.

If a battery is in good enough condition to start the vehicle, it's very unlikely to cause warning light malfunctions.

Firstly check all heavy connections - alternator B+, other end of this cable at starter terminal 30 and the stupid single M6 heavy tag on the battery connector (which usually ends up loose when the battery is disconnected for any reason).

Then eliminate all of the car warning light wiring by connecting a 12V 2.2W lamp between the WL terminal on the alternator (sometimes designated D+/61) and battery positive. A good alternator will show correct warning lamp function when run in this manner and maintain about 14.2V across the battery.

Is your machine a Valeo or a Bosch? It looks as though the recon was originally made in week 35, '02.

rotodiesel.

If a battery is in good enough condition to start the vehicle, it's very unlikely to cause warning light malfunctions.

Firstly check all heavy connections - alternator B+, other end of this cable at starter terminal 30 and the stupid single M6 heavy tag on the battery connector (which usually ends up loose when the battery is disconnected for any reason).

Then eliminate all of the car warning light wiring by connecting a 12V 2.2W lamp between the WL terminal on the alternator (sometimes designated D+/61) and battery positive. A good alternator will show correct warning lamp function when run in this manner and maintain about 14.2V across the battery.

Is your machine a Valeo or a Bosch? It looks as though the recon was originally made in week 35, '02.

rotodiesel.

Update is they've given me another unit, mine was a Valeo, and the 1st one was identical, today all he had was a bosch unit, same rating, but with one slight difference, it looks like it has another lead to go onto it, threaded thin screw on the rear casing, it fitted ok and has again turned the light out, the one I got yesterday was suspect as I felt I could hear it bearing rumbling with the engine speed, also whizz sound when turning off, the guys at the shop have given me a new battery to use for now as well, it's not the right one though, only a 60 amp one and it's too small for the battery tray clamp, I've packed it out to stop it moving for now, I did notice earlier if I took the plug off the alt the light would go out, this alone should finger the alt as the cause shouldn't it, or are there any earth problems I should look for under the car, i.e the other end of the plug wire which seems to go under the engine.

If you remove the small plug on the alternator the warning light will not come on.

rotodiesel.

It held up ok tonight, gonna get a new battery incase my old one has a fault that's causing the alternators to fail if thats possible, I noticed while I left it on charge one pole was hot and the other cold, is this normal or does it indicate something.

Now the 50 day old washing machine has decided to give me a dig in the ribs as well, is nothing made of any good grade material these days, I've found the fault, small propeller on the discharge motor, not even the quality of a cheap PC cooling fan, I ****ing give up.