Clutched Pulley

[Galaxy nig]

Hi can any one help I am new to the concept of clutched pulley but I was wondering if this could be the culprit here.we recently had work on our galaxy done after the steering became intolerable with screeching and vibrating we took it to our mechanic who diagnosed as being a shot suspension leg so he renewed along with belt and tensioner but this has not completely cured the symptoms altho they do appear better.so we still get screeching when turning and a bit of shudder.the power steering pump was also replaced at this point my question is this.is the alternator pulley supposed to spin freely in both directions as mine does and if I jam the armature with a screwdriver it don't turn at all either way so I suspect that's not good even g don't think that would cause judder so what would most likely be the next port of call.?cheers in advance for any help I would be most grateful Edited July 25, 2015 by Galaxy nig

[BrianH]

Your profile says its a tdi it may help to give an indication of what year etc the one your asking about is, as some do and others don't. The diesel is more likely to have a clutched one though.

 

http://www.fordgalaxy.org.uk/ford/index.php?/topic/26791-squealing-noise-alternator/?hl=pulley

 

You may have more luck posting in the tech board than the questions one (this one doesn't get as many visitors!)

[Galaxy nig]

Thanks Brian.I am new to this forum and I don't know my way around this site very well yet it is however 04 zetec 6 speed 130 brake.as the car has now done 82 thousand I would assume judging by what I've read it's getting ready for a new pulley so I think I'm going to change that anyway.I'll probs post in tech when get spare time.thank you once again.

[BrianH]

I guessed as much, Given the info above someone else should be able to confirm for sure, but based on whats been said (usually with vehicles with a DMF) I'd expect it to be a clutched pulley.

[Galaxy nig]

Thanks a lot

[daddyfixit]

alternator pulley will cause stupid noises on full lock;  on a lock it absorbs pulses caused by power steering pump--but when it fails/locks up  it cant so the belt squeals and groans. mine went with no warning the day it had a leaking steering rack fitted....I thought it was the power steering pump low on fluid.  mine has done 173k so I can live with that !!!    genuine item (valeo) from c.e.s Liverpool was £40 but special tool needed to remove the pulley once you have taken the drive belt off.

[seatkid]

Hi can any one help I am new to the concept of clutched pulley but I was wondering if this could be the culprit here.

 

Yes I can confirm your car 130bhp diesel has an alternator fitted with a one way clutch.

 

The reason it has one? PD equipped vw diesels have injectors that have exteremly short injection times at idle. Therefore the combustion process at idle speeds is short and very sharp. They also have light flywheels so that they can idle acceptably at low speeds. This means at idle speeds, the rotational speed of the crank is not constant but pulses up and down with each injector pulse. To protect the transmission from this high vibration level, they fit a DMF (dual mass flywheel) which uses springs and a secondary mass to smooth the output. The alternator is at the other end of the crank, which also has a ragged spped profile at idle. Because the alternator rotor is high inertial mass, they put a one way clutch on the pulley to protect the belt drive which would otherwise tug back and forth meaning short life and jumping and squealing.

 

Your one way pulley is seized (its easy to check but you have to remove the belt to check it), and its a very common failure. You can get replacement clutched pulleys (~£50 + labour IIRC), but they require special tools and some grunt to get it off the alternator shaft. Its quicker and easier to fit a new alternator but then again thats a fair bit more cash.

Edited August 1, 2015 by seatkid

[BrianH]

 

Hi can any one help I am new to the concept of clutched pulley but I was wondering if this could be the culprit here.

 

Yes I can confirm your car 130bhp diesel has an alternator fitted with a one way clutch.

 

The reason it has one? PD equipped vw diesels have injectors that have exteremly short injection times at idle. Therefore the combustion process at idle speeds is short and very sharp. They also have light flywheels so that they can idle acceptably at low speeds. This means at idle speeds, the rotational speed of the crank is not constant but pulses up and down with each injector pulse. To protect the transmission from this high vibration level, they fit a DMF (dual mass flywheel) which uses springs and a secondary mass to smooth the output. The alternator is at the other end of the crank, which also has a ragged spped profile at idle. Because the alternator rotor is high inertial mass, they put a one way clutch on the pulley to protect the belt drive which would otherwise tug back and forth meaning short life and jumping and squealing.

 

Your one way pulley is seized (its easy to check but you have to remove the belt to check it), and its a very common failure. You can get replacement clutched pulleys (~£50 + labour IIRC), but they require special tools and some grunt to get it off the alternator shaft. Its quicker and easier to fit a new alternator but then again thats a fair bit more cash.

 

If you relatively handy to tackle yourself theres an add in the classified section selling the pulley and tool at the moment.

[Galaxy nig]

Thank you for your explanation of the clutched pulley. I did have a vague idea of why it progressed but I didn't know exactly how it worked and why .your comments have been really helpful and I will post again once sorted