For 25 years I have been cleaning my engines with a hose and detergent. Usually when I change oil. Never had a problem on 15+ different cars. I don't cover anything. It's all designed to get wet.
I like a clean engine. It's easier to spot leaks and to work on
E90 328i Sport & Prem // R52 MINI S JCW // X3 x35i
62 Mini Cooper 997 // 62 Vespa // Laphroaig 30-yr