Drop the oil pan, apply air pressure to the cooling system, and hose down the entire crankcase with bubble soap, using a hand pumped spritz bottle. Walmart has them by the dozen. I keep several around the shop for penetrating oil, cutting oil, glass cleaner, and other stuff.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!