I sailed the boat home to San Francisco with my daughter, and noticed that the engine temp started to rise when the motor was driven over half throttle.
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Here is how it looked originally |
After stripping the water cooling system, I found that the exhaust elbow was almost completely blocked. The external paint was still good so there was no way to tell until the elbow was removed. The engine was installed new in 2004, so it was clear that the elbow had not been off for 20 years. This contradicts the standard wisdom that a nicely painted engine is a sign of good maintenance. It is actually the opposite - an engine with non-matching paint on all of the replaceable components shows that timely maintenance has been completed.
This is what the inside of the exhaust elbow looked like. The aperture was reduced to a hole about 1/2 inch wide by a build-up of exhaust soot. This mean't that there was enough water to cool the motor at low revs, but as soon as the revs increased and/or the engine load increased, the engine temperature started to climb.
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In addition to the elbow, I also dismantled and cleaned the heat exchanger, replaced the heat exchanger boots and hoses, replaced the freshwater engine water pump, and overhauled the salt-water pump.
The heat exchanger was cleaned by soaking in a weak muriatic acid solution.
I replaced all of the rubber boots and hoses to and from the heat exchanger, and used new hose clamps.
While I had the freshwater system apart I also put in a new freshwater pump, thermostat and fan belt. The old pump and thermostat had lots of gunk, but otherwise seemed to function fine.
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| Old freshwater pump and new pump. |
I also, replaced the salt water water pump components. Parts4Engines in the UK has kits for all the pump components and gaskets.
Also replaced the two fuel filers.
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| 10 micron R24T primary with water trap and |
Last but not least, I changed the oil and filter. This is a tricky job as there is no way to drain oil from the sump without making a massive mess. I purchased a vacuum pump and tank from West Marine, and sucked the old oil out of the dipstick hole. This sounds really difficult, but it is not. I also used the vacuum pump to suck out all of the old antifreeze coolant from the engine jacket, as it is also hard to drain from the engine block. I replaced the oil filter (parts4engines) refilled the engine with clean oil and the correct (green) antifreeze. The last step was fitting a new K&N style air filter (parts4engines), and we were all done for this round of maintenance.
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| Sucking out old oil through the dipstick. |
The engine now runs sweetly at no more than 90 celcius regardless of how hard the engine is pushing the boat. This was lots of work. I am now an academic, but my first career was as a tradesman marine fitter for the NZ navy, so I'm lucky to be able to do boat maintenance myself. I would hate to know what it would cost to pay a marine mechanic to do these jobs.
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| Lots of new components, but not really shiny - shiny on the inside |
Main Parts and Tool Costs:
$364 316 Stainless exhaust elbow (HDI Marine, also parts4engines)
$? Exhaust hose and clamps (Defender Marine)
$28 Thermostat kit (parts4engines)
$120 Water pump (parts4engines)
$74 Heat exchanger end caps/boots
$14 Heat exchanger tank cap (parts4engines)
$3 Exhaust gasket (parts4engines)
$13 Fan belt (parts4engines)
$40 Raw water pump kit (parts4engines)
$60 Silicone coolant hose set (parts4engines)
$33 Air filter (parts4engines)
$26 Fuel filter primary (Amazon)
$7 Fuel filter secondary (parts4engines)
$8 Oil filter (parts4engines)
$130 Oil Change Vacuum Pump (West Marine)
+ various clips and hoses
$ 920 Total (min)
