Re: evinrude 4hp yacht twin
Those can just barely mist out of the ports on the back of the leg and be just fine. I had one that wouldn't even mist at idle, but I ran it in a barrel, w/waterpump bulge completely submerged (pumps are not self priming, so you need to submerge 'em) at lowest possible idle and grab the cylinder head to check for overheating. I could grab it for a couple of seconds each try, and 15 minutes later, I was satisfied that it's cooling normally. Most folks replace the impellers every two or 3 years.. I usually just keep an eye on 'em. That motor has no shift shaft to unlink, so it's really easy to install a new impeller. Just don't pull up on the drive shaft after you have the impeller housing off, as the shaft will pull out of the pinion gear below and can be a bear to realign to re-insert.
