Silence...Sometimes it may be golden, but not when it should be pierced by the comforting purr of a boat motor. Thirty minutes ago my boat was humming along to that very soundtrack. Now, its silence is deafening, broken only by the occasional lapping of waves against a motionless hull. And judging by the lack of success of the few troubleshooting tricks I know, this issue may be serious. Time to call the mechanic. Yep, the mechanic. He could be a skilled technician, with plenty of knowledge of my particular engine. He could also be the type of shady dude who’s quick to diagnose a serious problem and hopes I won’t question his assessment, or the labor bill. Then again, he could be a really great guy — who just happens to be woefully underqualified for the job.
Whatever the case, I’m ready. A few weeks earlier I’d spent some time with Larry Hutt and Joel Hanks, two senior instructors at Florida’s Marine Mechanics Institute (MMI). This is where some of the nation’s top repair guys learn how to diagnose the basics before delving into overhauls. Hutt and Hanks have coached me on how to read the most common misdiagnoses. So, if this mechanic’s honest, we’ll get along just fine. But if he’s not, well, I know his secrets.
Secret No. 1: That overheating engine doesn’t call for a new water pump impeller.
Is the impeller really shot? You should be able to get about three years out of it on average. Keep good records, and note if things are prematurely failing. Hanks recounted several stories of engines overheating at higher revolutions per minute, and mechanics quick to change the impeller, when in reality the problem was a simple water restriction. In one case Hanks got tired of touching what he refers to as a “Chia Pet” on the drive. Turns out that the excessive growth was restricting the cooling passages, enough to cause overheating. A thorough scrubbing with a deck brush was all that was needed. Boat owners can also be fooled because of a faulty temperature gauge. Sloppy mechanics will trust the boat’s instruments, whereas skilled ones know to use only reliable shop tools, such as an infrared thermometer in this case.
