Monday, June 13, 2011

The Heat Exchanger

Good luck or bad luck - that's the question that I keep asking myself as I continue to find things that are screwed up on Sinbad. It's bad luck that I keep finding things's good luck that I'm finding them now and not on a passage a few hundred miles from land.
When we put Sinbad to bed on the hard last fall it had a nice dry bilge. This spring I found just a little engine coolant under our 80 horse Ford Lehman engine. I found the guilty hose right away but continued to inspect the entire system. That's when I discovered that a weld on one of the heat exchangers (think radiator) mounting bracket was broken. Not a fun job getting the two pieces off the boat to have them welded up. These surprise "jobs" quit being fun along time ago.

This is a picture of the heat exchanger with the bracket welded back on. For the folks that don't know how a heat exchanger works, water from the outside of the boat is pumped through tubes within the exchanger and motor coolant is pumped through the exchanger outside of the tubes. This prevents your engine from overheating.  So you would think all that remains to do is to put it back on the engine with new hoses. Wrong... or should I say "surprise". In the process of checking it out I heard a rattle inside it. There should never be a rattle inside of a heat exchanger. So it was time to do what I do best, tear it apart!

If you double click on the first picture it will enlarge, making it easy to see that some of the tubes are plugged. The second picture is after I pulled the end caps and ran a rod through the tubes. The pile of stones in front of the heat exchanger was what was making the rattle sound. It’s all that remains of a 30 yr old zinc pencil. The zinc is supposed to look like the one in the shiny brass base on the left side of the photo. Zincs are installed to protect the engine from electrolysis in salt water; they don't work in fresh water. I just happened to have the new one because it was on my "to do" list before heading into salt water.
In the long run this was  "Good Luck". It saved me from trying to figure out why the engine was over heating when we go through the Erie Canal.
Happy Sails........rr

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