You Asked:

How do you cool an inboard/outboard engine for test running out of the water? — Mike, Montgomery, Ala

Marshall Brain Answers:

A small outboard engine could be air-cooled, but most larger outboards use water from the lake/ocean for cooling. The lake acts like a giant radiator to keep the engine cool. There is a water intake port down near the propeller. So one way to supply water to run the outboard on dry land is to stick the outboard in a big bucket of water, like this:

The other option is to plug it into a garden hose like this:

There may be an easy way to attach the hose, or you may have to use a clamp-on rubber boot.

Lots of boaters will run fresh water through their engines at the end of the day, especially after running in salt water, to clean salt and anything else out of the cooling passages.