I say yes to this IF ...

Use a Pre cleaning organization plan - write it all out ahead of time. I do this because each time I get around to doing the engine cleaning I forget all the details that are important : get out cleaners, rags, pans, and cleaning chart for substrates.

WARNING: DO NOT clean a HOT engine!!! Reason: cold water can crack hot metal parts or block.

FIRST RULE: Use the least invasive or harmful thing first. (eg., Wipe off as much as you can with cheap rags or paper towels first, and then try the cleaners).

Disconnect - & + battery cables.

Clean the alternator, distributor, and coil, by hand.

Remove plug wires (you do want it to run better, right? or is this a cosmetic cleaning only?)

Cover: Oxygen Sensor, Alternator, Brake fluid reservoir-cap-breather-hole, Coil, Ign. Module, possibly other connectors with special plastic wrap (saran wrap works well if put on tight). But you can use big plastic bags of any kind and/or combinations. I've never had to clean to cover the Dist or Coil, but depending on the type of car you might have to. I have always been able to get any water out of these areas with after cleaning tricks.

Clean combinations of rubber and metal areas with Gumout engine degreaser (excellent and safe on all substrates), or Simple Green, or similar rubber safe cleaner.

Cleaning the very dirty metal areas with GUNK or similar type solvent is safe. Make sure it does not migrate to plastic or rubber or painted parts, though.

Clean inside the air filter box with a mild common cleaner solution - Simple Green properly diluted is fine.

Clean spark plug boot connectors with any cleaner, except rubber damaging ones. Rinse. Then use a moisture remover like WD- 40, or CRC 226, 336, 556, Power Lube, etc. Then CRC QD or similar electrical contact cleaner (make sure you get a plastic safe one).

Allow engine to dry. Use compressed air to speed up process. A hairdryer on the cold air setting is a good trick too.

Clean all electrical connectors with a plastic safe electronic cleaner after the engine has dried.

Clean drivebelts with a Rubber Cleaner, like Isophorone if you have it, or a common cleaner. Do the grip side with a belt spray if needed. I use DA on them (much cheaper and doesn't dry the rubber out much), afterwards to make sure the belts are free of any of the cleaners I rinsed off the engine earlier.

Clean outside of Hoses with Rubber Cleaner, or common cleaner. Inside will depend on materials inside. Castrol Super Clean works well. Possibly WD-40. Rinse out cleaner well.

Brake Rotors & Pads with CRC Brakeleen (careful not to remove the Grease).

Try not to spray high-pressure rinse the electrical stuff. Use the dielectric grease on the connectors afterwards, exception the O2 sensor connectors, which operates at very low voltage.

DO NOT use any silicone based products in the engine area. Silicone is highly migratory and can find its way into the fuel system in many insidious ways and eventually destroy the O2 Sensor.

NOTE: I used to use the high pressure washers on everything. Now I restrict their use to wheels, brake dust, etc. I found that if I boiled some water on the stove and used it very hot like that in a strong stainless steel insecticide pressure tank, I was able to melt the grease right off, usually without any solvents or cleaners.