Which pulley is best to use for the idler pulley on the alternator belt
mines collapsed ...zetec engine..
part number or vehicle it comes from would be helpfull

I used the idler pulley bolt and plastic spacer that sits on the block and the tensioner pulley...you know the one that fits on the alternator mounting bracket ....and generally the adjusting bit is seized... .... the idler pulley bolt and spacer fits inside the tensioner pulley, this makes a ribbed pulley that can then be used as a tensioner pulley mounted in a a slotted bracket to make the manual tensioner.