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Neuse Sailing Association

NAUTICAL SKILLS/ The Art of Diesel Maintenance


By Howard Cheetham
Immediate Past Commodore
m/v Hunky Dory

Before I give the stories, I'd like to thank Wade Ellison for spending an hour with me between Christmas and New Year's. He helped identify parts of the engine (before I'd taken the Mack Boring course) and gave lots of useful advice. For those who attended his seminar, I know you learned a lot. I recommend cementing that knowledge with some practical application. Get into your engine, do an oil change or a fuel filter change and find the water drain points. Check the impeller and belt. Identify the temperature switch, oil pressure switch, and at least mentally think through how you'd work on each system. You might save a bundle next time the engine needs some work. Now read on for my personal stories.

Many of you may know that we've had some engine problems with the old Cape Dory trawler we recently bought. During the inspection, before buying, the temperature alarm went off when the 200HP Volvo's revs went above 2300. Sure that it was a simple problem, we got a small discount from the seller which went on the first visit to Sailcraft. They found the raw water impeller cracked and barely pumping, and they replaced it – problem solved!

Well, almost, we now got to 3000 rpm before the alarm went off.

All the advice to this point, before going on the diesel maintenance course, was that it was probably build-up or a blockage in the heat exchanger. So I set about flushing the freshwater system but lost confidence when it came to removing the heat exchanger, and so I gave it back to Sailcraft. They did indeed find it dirty inside. They flushed and acid-washed it, but that still did not fix the overheating. And I'd now spent somewhat more than the seller's discount (getting close the the proverbial thousand in B O A T).

This is when we went to Mack Boring's diesel maintenance course. The hands-on activities did wonders for my confidence and the theory and process of "starting from the source and following it through the systems" was directing me to the thermostats next. I ordered new thermostats from Jarrett Bay and I set about replacing them. I deftly re-drained half the engine coolant, removed the thermostat cover and found one blown thermostat (photo).

Within a half hour I'd taken the two thermostats out, slipped two new ones in and had the cover back in place. To be certain, I'd also ordered a new temperature switch. I traced the wiring to find the switch (totally hidden behind the heat exchanger, under the exhaust manifold), found the right-sized (22mm) wrench and was just able to remove it while hanging upside down fumbling between hoses and alternator wires (this is the sort of contorting we really pay the diesel mechanic for).

Getting the new one in involved a lot more fumbling, but soon the job was complete and it was time to test it. At the dock I took the engine up to 4000 rpm without any alarm and watched the temperature gauge rise and then drop as the thermostats opened, then under load we took her out into the river and ran up to wide open throttle (3750 rpm under load) with the gauge staying below 190°F.

With muddled emotions of relief and satisfaction, we pulled in to Oriental marina to refuel, ready for a real spin up to New Bern the following weekend.

Which is the start of the next story…

Having refueled, I decided to alternate tanks to keep the fuel fresh, I turned the tank selection valve but forgot there is also a return line (Ed I believe I’m not the first to make this mistake!). We motored happily at about 12 knots all the way to New Bern, unaware that all of our fuel was being transferred to the starboard tank. On the return journey, just as I was questioning our distinct list to starboard, the port tank fed its last drops to the engine and with a couple of sputters the engine died.

My first thought was “damn, we inherited dirty fuel in that tank,” but as soon as we opened the engine hatch I saw the fuel return line valve and realized my own stupidity. I also knew that I’d need to bleed the fuel system. Fortunately this was something we’d learned and practiced.

I switched back to the full tank and heard fuel gurgle back into empty lines and filters, opened the bleed valve on the secondary filter until fuel came, and tried the engine. No success, I’d obviously gotten air past the fuel pump.

This is a much bigger job requiring an attack on the fuel injectors. No big deal, I’m now feeling like an experienced diesel mechanic. If there’d been more wind we may have needed to set the anchor, but on this calm morning we bobbed about in the middle of the Neuse River, half way back from New Bern with no concern of drifting.

I grabbed a 17mm wrench and cracked open all 6 injectors. The owner’s manual said advance the throttle full forward and turn the engine until fuel seeps from every injector, with a rag to avoid fuel spillage. Seeps? It was like the fountains at the Bellagio! And then the engines started (at full revs). Ros managed to get the engine shut down and I cleaned up the spilled fuel and tightened down the injectors.

We turned the engine and it purred back to life. As I put the engine hatch back into place I realized we’d saved an ignominious call to Tow-Boat and an embarrassing return to our dock (or Deatons), and stupidity was replaced with a great sense of pride and achievement. That was a task I would have had real trepidation starting at the dock before the training course, and may have gratefully paid to have it fixed. Now I know I can successfully handle it out on the water with a limited tool set and resources.

Of course, when sailing the engine is mostly out of sight/out of mind, but it is nevertheless important to be sure it is in sound working condition. I now know I can manage basic troubleshooting and maintenance when it may be important.

About the Author

Howard and his wife, Ros, live in Chapel Hill. They joined the NSA in 2008 and sailed a Beneteau 37, “Island Dream,” until 2013 when they sold it and bought a 44' Nautitech Catamaran, "MISTO," which is currently being outfitted for cruising in the Caribbean in 2015 and the World ARC rally in 2017. For now, they sail "Hunky Dory," a 28-foot Cape Dory Flybridge Cruiser, out of Whittaker Creek. They were Cruising Commodores in 2011 and Howard was named Commodore in 2013. 

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