Heat Exchanger Problems

I haven't mentioned it before, but the week between Christmas and New Years was scheduled to be "boat chores". Specifically, I needed to change the oil in the generator and engine. On December 26th, when I opened the engine compartment to change the oil, I was shocked and dismayed to find 3-4" of water in the compartment. A quick diagnosis indicated that there were a number of leaks in the raw water cooling system. When I ran the engine, a steady trickle of water was emitted from the "exhaust elbow". Probing it with a screw driver I found two holes, about 1/4" in diameter each, in the aluminum elbow, clearly the result of salt water corrosion. A closer inspection revealed that, in addition, the "heat exchanger" was leaking ... one of the end caps had corroded thru and the result was that the seat for the cap had been eaten away.

The heat exchanger is much like the radiator on a car. There are a series of small copper tubes thru which engine coolant runs. Instead of being air-cooled, like a car radiator, these tubes are, in turn, bathed in sea water, which is flushed out of the boat. The sea water goes thru the heat exchanger, then into the exhaust elbow, where it is joined to the exhaust from the motor which provides the energy to pump the water overboard.

It took me the best part of a day to get the heat exchanger and exhaust elbow off of the motor as they were shrouded by a labyrinth of pipes, wires, and acessories.

This was clearly a major problem. You would no more consider driving a car with holes in the radiator than you would driving the boat without a good heat exchanger and exhaust elbow. We got on the VHF net and called around and found a gentleman named Teapot Tony that could address the problems by flushing and cleaning the heat exchanger, having a welding shop build up the seal and then grind it down flat, with Tony rebuilding the heat exchanger with new gaskets etc. He also told me that he could have a new exhaust elbow fabricated from stainless steel, which would be much better than the original aluminum one. The only problem was that he could not start the work, and the welding shop would be closed, until January 3rd :-(

That being the case, I decided to pursue a two pronged approach. While waiting for Tony to come pick up the parts and get the work done, I sent out emails to various parts suppliers in the USA to see if I could get a new elbow and exchanger shipped to me post haste. Unfortunately, most of the places in the U.S. were also closed for the holidays, and when I finally got a quote back (about a week later), the heat exchanger was going to be over $3000! Yikes! Tony had said he could have it repaired for a couple of hundred dollars, and the new elbow fabricated for a couple of hundred more, so we decided to go that route exclusively.

When we finally got the parts back from Tony on Saturday, Jan 5, and re-assembled the motor on Sunday, January 6th (including putting new coolant in), we discovered another problem. The radiator cap was leaking. So we spent a whole day on monday taking busses and walking all over Puerto Vallarta trying to find a matching cap, which is non-standard because it's an English Perkins engine. We finally found what must have been the only one in Puerto Vallarta in a little auto-parts store near old-town, eliminating the final leak. After all was said and done, the engine work took us the best part of 5 days.

But, because of all the fun we were having in La Cruz, we didn't mind the extra 4-5 days we had to stay here. Nonetheless, it was with some satisfaction that we finally were able to start the motor and run it without any leaks.

Engine Problems