·Remove any excess debris; leaves and etc form the hood, grille or air-vent openings.
·Spray all electrical connectors with WD40, which repels water.
·Use cling-film or Saran wrap elastic covers to cover any sensors, electrical black boxes, electrical devises that could cause an electrical short-circuits if subjected to water spray.
·This will not guarantee that you wont cause a problem when cleaning an engine bay but it will greatly reduce the risks.
·Start and run the engine to get it warm, not hot, this will enable the de-greaser to work more efficiently on a warm surface.
·Apply an engine de-greaser (Autoglym Engine Cleaner) by lightly spraying the lower parts of the engine first and then working upwards.
·Do not allow the de-greaser to dry or remain on painted surfaces, and be sure to dilute with water and dry with a cloth.
·For heavily soiled areas agitate with a nylon engine cleaning brush and a diluted general purpose cleaner (P21S® Total Auto Wash)
·When the grease and grime is dissolved and you're ready to remove it, spray with a light (garden type) pressure water hose.
·Use the blower side of a vacuum (avoid area that may be sensitive to a forced air flow) or allow the engine compartment to air dry and then thoroughly wipe down all accessible surfaces and then remove cling-film or aluminium foil.
JonM