You need a special socket to undo it, it's a deep 21mm with a cut-out.

(Unless you remove all the injector pipes and the cam cover then they can be removed with conventional spanner)



http://www.ebay.co.uk/itm/FORD-MONDE...-/350582335681

Recommended to replace the high-pressure pipes.

New '0' seals that goes into the cam cover.

If you change injectors they need re-coding to the car, there's a 16 digit code on the injector that has to be inputted as an 'injector correction factor' using diagnostic equipment.