Posted: December 1, 2011
Would you believe a coat hanger fixed an overheating problem?
We have two diesel engines on our single-engine Krogen 42. Wait. What? Well, we have a 140 hp main propulsion engine that is really a marinized Ford tractor motor. That gets us from point A to B to C. We also have a little 3-cylinder 10 hp Japanese diesel engine that turns an AC generator. It’s better known as a Northern Lights 6 kw genset, and it ensures that we remain comfortable on the hook or at a dock with no shore power.For the last 1,800 engine hours, the main has kept running, reliably getting us to port each time we leave the dock, with the exception of an encounter with a 3-inch polypropylene towboat line that fouled the prop — a story for another day. The genset, however, has shut down a couple of times because the raw-water cooling circuit was clogged. Then it got too hot.
Why does the main stay cool and work well while the auxiliary generator gets clogged and quits? Two reasons come to mind. First, there is no intake grill on the outside of the genset through-hull. Second, the boat is moving most of the time the main is running, but we run the generator while we sit relatively still at anchor. The bays and inlets where we find shelter are often filled with kelp, and the raw-water intake can act like a seaweed vacuum.
The last time the genset shut itself down, I guessed it had become too hot. We have no genset temperature gauge, but I could see the coolant level in the reservoir had increased. I looked at the strainer and saw seaweed. I thought, “Good, I’ll just clean that out, and we’ll be back in business.” Au contraire. I cleaned out the gunk and restarted it. It shut down again after a few minutes.
Since the strainer was clear, my next thought was that the raw-water impeller must have worn out or come apart. I closed the through-hull again and pulled the plate off the pump housing, only to see a perfect impeller. I had my wife bump the start switch just to ensure the impeller was turning as it should. It was.
Now what? I was out of ideas. I went back to the through-hull, opened it again and noticed the strainer was not filling quickly. I closed the valve, pulled the hose off and slowly opened it again. Just a trickle of sea water came through. I got my specially made piece of wire coat hanger, poked through the valve and, voila, it was a gusher. I was never so happy to see my engine room flooding; I had solved the problem. I shut the valve. The kelp had plugged the hole outside the hull, and now it was fixed. Maybe I should have thought of this scenario first, but then I’m no expert. I’m just a guy with a boat.