can i drive up to a car wash and open the hood and just commence to spraying my engine (the entire engine) with the water hose to clean it? will it ruin some parts of the motor?
No, you can’t throw (or, spray) water on your engine without negative consequences. If you did, you would have the equivalent of a “flood” engine.
The resulting problems would be “interesting”.
There are products that are made for this…Gumout Engine Cleaner is one. Spray on…and hose down after 15 minutes. Read the directions. You’ll need to take precautions about covering electrical and ignition components. I usually do it once a year with no ill effects.
A car wash is the worst place to clean your engine. The high pressure drives water places it shouldn’t be, and spraying cold water on a hot engine is asking for trouble.
There are engine cleaners available at auto parts stores. Use one and follow the directions to prevent damage.