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
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
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.