Well once again my alternator is playing up.

About a year ago now I got a second hand one to make it easier as a special tool was needed to change the bearing plus the bearing was expensive.

Now today ive been to tps and got one as I dont want to be changing it again for a long time.

Symptoms

Slight ticking starts at low rpm .

Over time this gets worse and starts to sound like something is loose. Not the nicest and you get looked at like your car is about to fall apart.

If left it then starts to become a loud squeek/screech. Doesnt seem to go away.

Then if still left the noise goes completely. BUT this is not a good thing as it means the bearing in the pully has totally seized up.

The bearing works by allowing the aux belt to spin freely with less resistance allowing less power sap until you hit a certain rpm. I think this is over 2k rpm. After that the bearing locks spinning the alternator up and charging the battery.

I have been cought out before on the drive home where ive kept it below 2k all the way and when I was nearly home after 50mins drive I had loads of light on the dash come on. Lucky I stopped on a hill as I needed to bump start the car and give it some for the last few mins lol.

Anyway the part you need is

022 903 119c pulley

Cost, well brace.

£53.50 +vat and thats with discount.

Lucky I managed to borrow the tool needed to sort it out.

Ill see about a quick write up when ive done it.

Got the brakes on my wifes coupe to do and still playing around with the M5 lol :-s

Bugger paying that for a pulley!

My alt went couple months ago and I got a complete alt with new pulley for just over £100.

I know its a lot.

But its oem and so far I am hoping not false economy like buying used or even none oem. I dont particularly do that if I can help in. Like to keep things genuine.

My used one lasted a year ish so tgis one needs to last 18 months and I am in pocket lol

The Sprague clutch allows the alternator to freewheel. Basically when you lift off the power and the revs drop the alternator can continue to spin at high speed.

If you spin the alternator by hand with the belt and then hold the pulley the alternator will continue to spin.

If you think of the size of the alternator pulley compared to the pulley on the crank then the the alternator spins many times faster than the engine revs at. Without the pulley every time the engine revs drop then the alternator would suddenly slow by several thousand rpm and that is a lot of energy to dissipate.

Sent from my Nexus 4 using Tapatalk

ahh

cheers for that so it works in reverse to what I thought,  makes more sence that cheers, ignore what I said then.

 

how come mine makes the rattle noise when accelerating tho? not when lifting off? 

 

mmm Ill see what happens when I change them

It maybe about to fail completely?

Sent from my Nexus 4 using Tapatalk

the last one did the same mate, didn't fail just seized up completely. so when you turned it it spun the alternator where this one I got used didn't, the bearing spun freely.

They can disintegrate and the outside comes away from the centre.

Sent from my Nexus 4 using Tapatalk

Did you change the tensioner when you changed the pulley?

If not it's probably worth doing, along with the belt.

Sent from my Nexus 4 using Tapatalk

Mmm well hope it dunt break totally.

Done the belt and the tensioner does need doing too but gonna do it at samt time as cam belt as it looks a pita so ill have the garage do it lol