Cleaning the carbon out

[Michaelwilson]

Saw a video on YouTube the other day with this guy just spraying water into his intake to clean out carbon inside the engine he was doing it with a spritzer bottle. You needed to get your engine to operating temperature and 2 to 3 thousand rpm. Any truth or is crap.

 

[stamp11127]

Truth. The water turns to steam and has a cleaning effect.

Also evident when a head gasket lets go leaking coolant into a cylinder. Cleans the snot out of everything.

 

[Michaelwilson]

So short of taking the head off, which I don't want to do, Ever. How do you know it's clean, or are reasonably sure?