To be honest, I was used to use the pressure hose quite a bit on the EA bay. However, I noticed that all the little terminals in the engine bay corroded quicker, and if the ignition leads were not up to scratch, there would be starting issues.
I still use high pressure on the actual block (exhaust side), as well as under the car, however, I prefer to wipe the 'electrical areas' with a rag, and polish the places that need it.
For the real dirty engine bay, you cant go past degreaser, Hot soapy water, a good scrub and a good rinse.
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