My advice about washing engines is DON'T!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Customers would get angry when their new Jaguar would not start after washing the engine and demanded that it be repaired in NEW CAR WARRANTY.

We refused to warranty repair a 'self-inflicted' problem.

Jaguar issued a TSB on the hazards of washing certain areas.

Here is an excerpt.

CLEANING AND DETAILING CHEMICALS
A further concern is the use, especially in the engine compartment, of cleaning and detailing
chemical products, particularly those containing silicones.
Detailed investigations have indicated that the entry of silicones into electrical components
(particularly relays, connectors and components containing printed circuits) can cause
intermittent operation or complete failure.
Jaguar does NOT recommend under hood cleaning as a routine practice, nor the practice of
applying by spray, detailing products to the engine, engine bay, under hood pipes and hoses, and
other components to obtain a ‘showroom’ finish. If a high finish is desired, hand detailing is
recommended.