Or at least i think it is.

If any resident genius can answer I will be grateful.

 

I've just had to have the pully on my alternator changed because of the clacking noise it was making. I kid you not pedestrians were starting to stare at me !!!

 

I've looked at the old one and it looks perfect but i was told all the thingies inside were done for.

£64 for a new pully wheel.

 

Question ---what "thingies" are inside a pully wheel for the front end of an alternator on an Octy diesel ?.  Ratchets?  Clutches? Springs?  Imps?

 

Many thanks.

The alternator has a dampening pulley. 

 

So it will probably at least have springs in it, and maybe some sort of dampers.

It's a one way pulley, drives one way and free wheels the other.

Brilliant and quick !!.  A one way dampened pully indeed. Cripes.   Why would it ever need to free-wheel ?

 

Do they pack up often?  They had it on a shelf--no ordering in malarky. Probably do ten a week No-one mentioned an Imp.

 

If I stick my finger in the threaded hole in the middle and try to turn the outer part it won't budge in either direction.  Must be seized up solid---suspect it is because today it stopped its terrible clacking racket and started to squeak.

 

That's it I'm selling it !!!

 

Thank you.

Brilliant and quick !!. A one way dampened pully indeed. Cripes. Why would it ever need to free-wheel ?

Do they pack up often? They had it on a shelf--no ordering in malarky. Probably do ten a week No-one mentioned an Imp.

If I stick my finger in the threaded hole in the middle and try to turn the outer part it won't budge in either direction. Must be seized up solid---suspect it is because today it stopped its terrible clacking racket and started to squeak.

That's it I'm selling it !!!

Thank you.

Given the relative size of the alternator pulley and crank pulley, think how fast the alternator spins. When you change gear the engine revs drop suddenly and the alternator would have to instantly slow down by several thousand rpm, that's a lot of energy to disperse. The one way pulley allows the alternator to maintain speed during gear changes etc.

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When a diesel engine stops due to the high compression they rock back half a turn. They found that the aux belt was tight enough to crack the pulley off and it unwound and came off.

And yes they are very common and have been since the 90s.