My brother's 2008 Focus 1.8TDCI. Charging fault, low alternator output measured across battery terminals and from the main output terminal on top of alternator. he had to call AA out as battery was flat 20 miles from home. They said alternator bad and my voltmeter tests seem to confirm that.

So my brother bought 2nd hand alternator on ebay. This morning he brought car round to my driveway so we could fit it. Before we got alternator off we found that the alternator pulley that the belt goes round was all loose, loads of sideways play on it. feels very dry and squeaky and does not grip to the central shaft when turned in both directions. Loads of rusty dust/iron fillings coming out of the pulley

In case anyone is not aware of the unusual arrangement on this engine, this is how alternator and the extra drive shaft look:

https://www.ebay.co.uk/itm/Ford-Focus-Mk2-1-8-Tdci-Diesel-Alternator-With-Extended-Pulley-2005-2011/143077776743?epid=11017977464&hash=item2150199d67:g:rfUAAOSw5-hb9ZNH:rk:6:pf:0

So he now needs to buy the pulley/shaft part. 

the pulley seems to have some kind of one way clutch I think from reading other stuff. Can anyone tell me this  - when we get another one, to check it seems ok, how should it feel, eg. should the pulley not grip the shaft when spun clockwise and grip it when anti-clockwise or vice versa ? or not grip in either direction when spun by hand because it only grips above a certain spinning speed?    Can anyone tell me, as I would rather be confident the 2nd hand replacement part seems OK before fitting it.

Yes I know we should never buy parts until the dismantling has been done so as to be more sure where the problem really is. At least the alternator was only £25 incl postage.

For a while the car had made a strange intermittent squeak from the engine area and we could not identify where it was, but I think it was probably that alternator pulley so hopefully that will have gone away when we put the new pulley on. 

 

 

The freewheel pulley is designed to let the alternator run down slowly once you let off the throttle and between gearchanges instead of a harsh drop in speed each time the RPM drops.

So the pulley should lock when turned one way, and spin freely (with very slight resistance) the other way.  I'm pretty sure it turns clockwise on that engine (though best to double check with the engine running) so should lock in the clockwise direction, and spin in the other.

OK thanks, a 2nd hand replacement has been ordered on Ebay. Hope it's in good order. 

Just an update on this: got the pulley/shaft thing. Was about 15 quid incl postage on ebay 2nd hand. Tested by hand, seems to work perfectly. Fitted to car. Now charges fine. And the intermittent squeak from engine bay has not returned (at least not yet).

So, moral of this story, don't assume it is alternator without checking the one way clutch pulley on the end of the extra alternator drive shaft