Episode 30 - Diesel Engine Part 1

For the last year, the biggest question for me, as far as the boat was concerned, was what to do with the diesel engine. Should I recondition it or replace it?

The engine had slowly dripped oil since I had bought the boat, a Cavalier 28 called Bolero, in October 2019. It was a known problem and, rather than being fixed, it had been accommodated by placing a paint tray under the engine to catch the drips. Last Christmas (2020), the engine began to slowly drip diesel fuel. Again, I accommodated the problem by turning off the tap to the fuel hose after every trip, and emptying the paint tray under the engine at more frequent intervals. 

The actual leaks themselves could not be classified as an emergency; diesel fuel is not as volatile as petrol or gas, and it is not easy to light it, but it is not good to allow the situation to continue. More importantly, the smell and the worry of growing puddles of flammable liquids down below kept the Admiral off the boat. Something had to be done.

The engine was a single-cylinder Bukh DV10 LMSE with an external flywheel. As far as I could determine, it had been installed in the boat when it had been built in 1984, so it was almost 40 years’ old. I was faced with the following options.

OPTION 1 - Do Nothing and sell the boat

Pros: This is, obviously, the cheapest option with the added potential of inflated prices in the market as folks spent their money on COVID toys, including boats.

Cons: This would leave me with no boat. The inflated market meant that I would need to spend more on a new (used) boat, with the risks that the new (used) boat would have its own list of expensive and difficult problems. In any case, Bolero, is a nice boat with a reputation for competing well in races and it is perfect for what I use it for - mainly day-sailing in Moreton Bay with family and friends. It would be difficult to replace.

OPTION 2 - Replace the engine with a new engine

Pros: There would be no question of the engine problems being fixed, including the replacement of the rats’ nest of wiring that had evolved around the current engine. The new engine would be an upgrade from my current 10HP to something with a little more power, and would come with a ready supply of replacement parts. I got quotes for two engines that would fit my current drive-shaft and propellor

Nanni N2.14 - about $9600, including GST, engine, mounts, exhaust elbow, wiring and controls. The N2.14 is a two-cylinder 14HP engine with a heat exchanger

Beta 16 - about $9800, including GST, engine, mounts, wiring and controls. The Beta 16 is a two-cylinder 16HP engine with a heat exchanger.

NB: When choosing a new engine, you need to take the propellor into account. The style and pitch of the propellor needs to be matched to the working or maximum revolutions per minute (RPM) of the output. In my case, the propellor had been designed for the Bukh, which spun at a maximum of 3000 RPM. Because the boat came with a worn flappy, folding propellor, I replaced the propellor and shaft in 2019 for about $1500. The Nanni and the Beta would both spin up to 3600 RPM, which was still within the performance curve of the new Bruton folding propellor, and I was loathe to replace the prop with another replacement.

Having got the prices for the Nanni and Beta, I “rounded up” the budget to about $15K with a generous allowance for unforeseen work, which might include major surgery to the engine beds, slipping and specialist trades. I found this difficult to justify, as it was approaching 3/4 of what I had paid for the boat (in a private sale). As a comparison, I recently noticed another Cavalier 28 for sale with an asking price of $40K. 

Cons: This is, obviously, the most expensive option. There were also residual, unavoidable risks in fitting the new engine to the boat, though the wrights would do a proper job.

OPTION 3 - Repair or recondition the Bukh

Pros: Likely to be cheaper than a new engine with fewer risks of fitting it to the boat.

Cons: Replacement parts would be difficult to find. No increase in power (it would stay at 10HP). Risks of finding un-fixable problems.

Regarding the power, I thought it would be nice to have a little more grunt. But, the current engine was capable of 5 to 5.5 knots on flat water (e.g. getting in and out of harbour, and motoring on calm days). The previous owner had claimed that it would do 3.5 knots into a chop with a dingy in tow. The latter case would not be comfortable or pleasurable, but it would likely be the worst conditions I would sail in. Incidentally, I found that maintaining a clean bottom and a clean prop makes a big difference to boat speed, and for about $130, I could hire a diver to give the bottom and prop a scrub. There is more than one way to skin this particular cat.

The Bukh DV 10 LSME is cooled by direct salt-water injection, meaning that it sucks seawater straight out of the sea, circulates it around the engine-head and injects it into the exhaust elbow. It has no heat exchanger. There was no way of telling what damage had been done to the internal galleries around the engine-head by hot saltwater and calcium deposits.

Bukh engines are also remarkably primitive; deliberately so to increase their reliability for the lifeboat engines that Bukh manufactured. The Bukh DV 10 LSME has an external flywheel and mechanical injection. This means you can hand-crank the engine and run it with no electrical inputs whatsoever. The flywheel has a fitting for a starting chord. As an engineer by profession, I am instinctively drawn to the as-simple-as-possible solutions.

The Bukh DV 10 LSME is a rare beast, nearing extinction. Only about 100 or so ever built and it is now out of production. As I was to find out later, the number of replacement exhaust elbows has dwindled, and I was lucky to find one of only two known replacements in the Southern Hemisphere.

The remaining risks with this approach were to do with the engine beds, which looked shonky, the wiring, controls (which were well-worn) and peripherals, such as the exhaust elbow.

OPTION 4 - Replace the diesel engine with an electric motor

Pros: Quiet engine with no smelly oil or diesel fuel.

Cons: Cost. Although an equivalent electric motor would cost about the same as a diesel motor (say $8K), the batteries would cost several hundred tanks of diesel fuel. My current diesel consumes about $3 to $4 of fuel per hour. It might even lose more fuel to leaks than it burns. I would need about $5K to $7K of battery for each hour of electric ‘steaming’, and would need to upgrade the electrics from a 12V to 48V, which is well beyond my current capabilities. Furthermore, there remain safety concerns about getting trapped on a lee shore with flat batteries. It can be done, but the technology is still being developed. If you need to know more, I suggest you watch the Sailing Uma Youtube channel.

NB The term ‘steaming’ is obviously of historical origin and generally means propelling a sailing boat by using the engine. If it became anachronistic with the advent of diesel, it is now doubly so with the advent of electric engines.

Choose Option 3

The Bukh engine already started, ran and stopped nicely. Its only real problems were to do with its slow leaks, rather like an incontinent old family dog.  In the end, I found I did not have the heart to put it to sleep, so I chose to recondition the Bukh. 

If the reconditioning failed, requiring me to buy a new engine, I would at least have learned something about diesel engines, which, up to this point, were a complete mystery to me. Also, the process of removing the engine and taking stuff apart would likely uncover the hidden problems that would affect the refitting of a new engine. In any case, this seemed to be an incremental approach, meaning that I could work my way in slowly, and figure out the next steps as they arose.

The first thing I did was to get some video of the engine starting, running and stopping (see video below). This was proof that, whatever would happen next, I had started with a running engine.

The next thing was to remove the engine. Because of my earlier explorations, searching for the fuel leak, I knew my way around some of the engine, and had made life much easier by cutting a large removable hatch through the head compartment divider on the port side. However, it was dirty work taking off as many bits and pieces as possible, working with seized nuts and bolts, trying not to damage stuff and recording progress with notes and photos. It took a couple of mates to finally get the engine out of the boat. 

Lesson learned: When maneouvering a heavy lump of diesel engine around a boat, make a timber cradle or sled. I knocked up a pine cradle and strapped it under the diesel, and found it helped enormously. The big advantage is that you can put the heavy lump down on things like the floor, the companionway hatch, the combings, without damaging them. It also gives you useful hand-holds. Never attempt to manoeuvre an engine without a cradle.

I found that the forward starboard bracket had sheared completely, leaving the engine supported on the remaining three brackets. Half the forward weight, which included the heavy flywheel, was being supported by the starter motor leaning on the bearing stud. All the rubber bearings were in poor condition and the holes for the holding-down bolts were set into black, soggy timber.

I needed a mechanic willing to do the work. Diesel Works in Loganholme, QLD, said they would do it, and seemed undaunted that the engine was old and unusual. Without holding them to a quote, I asked how much and how long, and was told about $2K and 2 weeks. This was attractive, even allowing for some extra time and money. In the end it cost about $2800 plus GST and took about 6 weeks. The main causes for the delay were finding a replacement set of gaskets  (a single set of gaskets for this engine cost about $700 from the Bukh dealers in Sydney) and finding information, such as the torque settings for the engine-head bolts. The DV 10 LSME has an alloy engine head, so there was a greater risk that over-tightening the bolts would strip the threads than for a cast iron equivalent.

Lesson learned: Don’t assume that the mechanic knows everything about the engine. It would have helped if I had some some internet searching beforehand and handed over copies of the workshop manuals with the engine. Also, as it turned out, the Australian suppliers of the Bukh parts were more expensive and less well stocked than their competitors, The Engine Room in Auckland, New Zealand. In future, I’m getting my Bukh parts from The Engine Room.  If you intend to recondition your engine, find the manuals and a supplier or parts before dropping it off at the mechanics.

Diesel Works did a good job, though it was frustrating to be told, week after week, that it would be ready for collection the next week. The external casing had been badly corroded on the port side, probably because a split in the exhaust elbow had been blowing steamy sea water onto the engine block at this location (I would need a new elbow). Diesel Works took the engine apart, cleaned it up, sealed the gaps, and demonstrated that it ran. They also got some some parts working that had been seized for years, such as the manual fuel pump. The thermostat was broken beyond repair (I would need a new thermostat), and no fixes were attempted on the temperature and oil pressure gauges, which had ceased functioning long before the boat came into my ownership.

I got the new, shiny version of the engine home and started to measure up for the engine beds. I ordered a new exhaust elbow and thermostat from The Engine Room, for about $690 including tax, postage and credit card surcharge. I also bought new bearings and a coupling from Polyflex in Clontarf, QLD, for about $930 including GST.

The running total for the reconditioned engine is about $4700 including GST, and I have yet to get to the wiring and controls.

I am currently rebuilding the engine beds, which I will address in a new episode.

Bukh DV10 LSME after reconditioning