Engine Temp: Lessons Learned

[CHM]

Last weekend, I took the boat out toward the Canaveral Locks after it sat in the slip for 3 months. All was well until the engine alarm sounded and i saw the temp gauge pegged at 250. I immediately stopped the engine and set the anchor in the narrow channel. The impeller was only about 6 months old and I saw sufficient water from the exhaust when I first started the engine, but I changed it anyway. We weighed anchor and tuirned back toward the marina to see if that was the problem. Needess to say, the temp began to creep back up so I docked the boat and allowed the engine to cool. I checked the coolant and it was down about a quart, so I topped it off and was certain I fixed the problem. WRONG! I took the boat out the next morning and engine temp creeped up to close to 200-210, so back to the slip. I checked the engine strainer under the boat and it was completely clean. At this time, I had to call in the big guns - the mechanic. He called me and sent me photos of a completely plugged heat exchanger, full of old gelatinous anti-freeze. Apparently, the previous owner did not keep up with this detail. The heat exchanger is currently in an ultrasonic bath and will be re-installed with a new thermostat. I can upload photos of this mess if anyone is interested. I am looking forward to some water sailing">blue water sailing in a couple weeks.

[twinboat]

I learned the same lesson 4 years ago, when my 1984 engine ran hot wherever I went above 7 mph. The last owner did all kinds of things to keep it cool, including putting the wrong prop on to keep the rpm's down. When I pulled the exchanger core, it reminded me of the old STP comercial. I could'nt hold it, it was so slippery, covered with gell. I flushed the block out and sent the core to a radiator shop. It has not overheated since.