Repowering, Part 1, The Decisions

Repowering, Part 2, Replacing the Power Plant

New engine or rebuild? And should you install it yourself?
by Don Launer

Chances are your boat is like a member of the family. You could no more dispose of it than sell your only child. But, inevitably, the day arrives when you realize that your power plant is on its last legs, and there are some important decisions to be made.

Some boat owners go to the boatyard, write a check, and say effortlessly, “Call me when it’s ready.” For most of us, however, it’s a traumatic moment. After all, repowering an inboard auxiliary sailboat is a lot more involved than simply dropping a new outboard onto the transom.

For diesel engines, the symptoms begin to develop years before things become critical. Whereas your brand-new diesel would start within the first turn, now the cranking takes longer — and, if the weather is cold, much longer.

When Rudolf Diesel first patented his engine in 1892, it was a revolutionary idea. His engine used the principle of auto-ignition of the fuel. This idea, based on the work of English scientist Robert Boyle (1627-91), was that you could ignite the fuel from the heat produced by compressing the air in the cylinder. If this compression were great enough, the temperature in the cylinder could be raised enough to ignite the fuel-and-air mixture. In modern diesel engines, this compression ratio is between 14:1 and 25:1, which raises the temperature of the air in the cylinder to well above the burning point of the diesel oil that is injected into the cylinder (about 1,000 degrees F).

Compression, then, is the key to a successfully operating diesel. But when a diesel is up in years, cylinder walls and piston rings are worn and fouled with deposits, so they no longer make a good seal. Valves and valve-seats have also become pitted and fouled and don’t seal properly. Thus, it becomes much more difficult to get the compression necessary for ignition, especially when the engine block is very cold and rapidly saps away the heat of compression.

Discussing the proposed engine replacement with Tom Dittamo of Harbor Marine Engines. The new Yanmar 3GM30F is delivered early, which gives Don adequate time in which to measure it and familiarize himself with it.

Biting the bullet
When the day finally arrives for you to bite the bullet, there are two options: get the engine rebuilt or buy a new one. If the horsepower of the old engine was perfect, if it pushed you through heavy winds and waves when they were right on the nose, and if that engine has always been freshwater-cooled and has not had other serious problems, rebuilding that old engine might be more compelling. Certainly it would be less expensive.

But if your present engine is very old and has had raw saltwater cooling, chances are that having it rebuilt will not be practical. There will be rust, frozen bolts, parts to replace, and probably great difficulty in getting those parts. Even though the cost of rebuilding an old engine is typically about half that of a new engine, you may very well be throwing money away on a rebuilding venture. And if you have always felt that you could use just a few more horsepower to get you through those nasty conditions, now is a good time to upgrade.

Remember that when you decide to go with a new engine there are many more costs involved than just the price of the engine itself. Engines today, which provide the same horsepower as your old engine, are usually lighter and smaller and rotate at higher speeds.

These smaller dimensions in width, height, and length make it almost certain that your engine bed will have to be rebuilt to accommodate the smaller engine, since its mounts will probably be closer together.

It’s also important to know the type of transmission on your new engine. Basically, there are three different types:
• Parallel is a transmission whose propeller-shaft coupler is in line with, or parallel to, the engine’s crankshaft.
• Angle-Drive is a transmission whose coupler is at a downward angle to the crankshaft.
• V-Drive is a version in which the transmission is forward of the engine and makes a V-turn to drive a propeller shaft leading aft.

Each of these configurations presents its own problems when rebuilding the engine bed.
The smaller fore-and-aft dimensions will probably also mean that you’ll need a new and longer prop shaft unless you can set the new engine farther aft on the beds. Having a new shaft is probably a good idea anyway. After the old engine has been removed and the old shaft has been slid out of its stuffing box, you’ll probably see rings of wear in the shaft where the stuffing box (and sediment) have created grooves. If your old shaft is more than a decade old, you’ll probably find that the flange coupling is so frozen onto the shaft with rust that it’s impossible to free it without further ruining the shaft.

Also, if you didn’t previously have a flexible coupling or Drivesaver, now is a good time to add this item, which will help protect your new transmission in the event of the propeller picking up a piece of wood or a heavy line. If you’re already using a flexible coupling between the engine and the shaft, chances are that the bolt holes in this flexible coupling or Drivesaver will not match your new engine’s coupler, and a new, matching, flexible coupling will have to be purchased.

As for the propeller, there’s a 50-50 chance that the new engine may rotate in the opposite direction from the old engine. (If your present engine turns the prop shaft counterclockwise in forward gear, as seen from the stern, you now have a left-hand prop. If the new engine has a clockwise rotation, you need a new prop.)

Even if the direction of rotation of the new and old engines is the same, chances are that the engine speed, the horsepower, and the transmission gear ratio of the new engine will be different from the old. This will probably mean a new propeller of different pitch, diameter, or number of blades, making your old prop obsolete.

Free consultation
Most engine installation manuals give charts showing the recommended prop for your particular displacement and hull configuration, and most propeller manufacturers provide a free consultation service to determine the type of new prop you’ll need when repowering. Michigan Propellers, for instance, has a Pleasure Boat Prop-it-Right Analysis Form, which will suggest the correct propeller for your new engine.

On some boats, the engine and propeller shaft are deliberately installed at a slight angle off the fore-and-aft centerline of the boat. This may have been done to offset the tendency of a single engine to push the stern to one side or the other or to allow the shaft and prop to be removed without removing the rudder. If your boat has an offset driveshaft, repowering with an engine whose shaft rotates in the same direction as the old engine may be preferable. (We have an offset shaft on our C&C 30. We repowered with opposite rotation and are satisfied with the outcome. It seems like this should have mattered more than it did. —Ed.)

The smaller proportions of a new engine and the rebuilding of the engine bed will also mean that your present oil drip pan beneath the engine will no longer fit, and a new pan will have to be fabricated and installed.

There is one complication of a physically smaller engine that may be overlooked. If you’ll be using your engine to supply hot water through a heat exchanger, the water connections on the new engine might well be lower than on the previous engine. If the heat-exchanger water lines from the engine to the hot water tank slope upward, an air-lock can develop in the heat-exchanger coil in the hot water tank that will prevent water flow and, consequently, heat exchange.
One way to overcome this problem is by installing an expansion tank at the highest point in the water lines at the hot water tank. The pressure cap on this tank should match that of the one on the engine, and filling the water system can be done through the filler cap of the new tank.

Fuel-return line
With diesel engines there’s another thing to consider. Some diesels had just one fuel line going from the tank to the engine. Most modern diesels, however, also require a fuel-return line from the engine to the tank (often called the overflow fuel line). Depending on an engine’s design, the amount of fuel returned to the tank via this line can vary greatly.

If you had an engine with a single fuel line, the chances are that you don’t have a fitting on top of the fuel tank(s) for this new fuel-return line. This problem can usually be solved by removing the current air-vent fitting at the top of the fuel tank and substituting a T-fitting. One side of this T can then still be used for the air vent while the other side can be used for the fuel-return line. This problem also will be encountered when changing from a gasoline engine to diesel.

It’s also likely that with a new engine, the water, fuel, and exhaust systems may have to be rebuilt or re-sized. Even if this isn’t the case, when the old engine is removed is a good time to replace those old hoses.

If you are considering selling your boat within the next few years, it might be tempting to believe the value will increase enough to offset the money you have put into a new engine and its installation. But although a boat will be worth more with a new engine, the increase in value will probably not equal your investment when you sell your boat. The same caveat is true if you convert from gas to diesel. But here we are discussing repowering your boat because you want to use it for many more years, not with the idea of selling it.

Do it yourself?
Most owners will hand over the repowering project to a knowledgeable, qualified, and reputable installer. Still, it’s valuable to know the potential problems along the way. If you have decided to have the job done professionally, there are several preliminary steps to take:
• Only accept bids from installers who have actually examined your boat.
• Consider the reputation of the installer and the yard.
• Ask whether they have installed this type of engine before.
• Ask for references from owners of boats similar to yours who have had the same job done.
• Make sure that all associated work is specified on the proposal.
• Be sure that the final installation will conform to American Boat and Yacht Council (ABYC) standards.

Some boatowners will want to tackle the job themselves. If you do your own installation, there are much greater benefits than saving money. You will end up with an intimate knowledge of your new installation. This, alone, is a great incentive.

If you decide to do the job yourself, it’s still a good idea to have a professional in your corner, someone who is a dealer for your new engine or who has done engine installations, and whom you can trust, talk to, and order parts from. If you’re doing your own work, the closer the yard is to your home, the better. And if you don’t want to tackle the whole job yourself, you may elect to do just the engine rewiring, the exhaust system, the water system, or the fuel system, after the new engine has been installed on its bed and aligned.

Whether you do it yourself or have the engine installed by a professional, the job requires engineering judgment and good mechanical skills.

We were fortunate that for years there was an engine mechanic near us who would give us excellent and detailed advice whenever we had a do-it-yourself engine job to tackle. Tom Dittamo, owner of Harbor Marine Engines, in Lanoka Harbor, N.J., has his business in a marina less than 15 minutes from our home. Tom is also a Yanmar dealer, so we chose that yard, Laurel Harbor Marina, in Lanoka Harbor, for our haulout and engine replacement.

We bought our new engine from Tom six months before beginning our project. He stored it in his shop at the marina during this time, which allowed me to go in for all the necessary measurements whenever I needed to. This enabled us to plan well ahead for our project and purchase all the ancillary gear necessary. (This early engine purchase, which was suggested by Tom, also saved us 5 percent on the manufacturer’s price increase that went into effect shortly after we ordered the engine).

Replacing an engine often means replacing the propeller as well. The C&C 30 gets a new right-hand Michigan Wheel 15 x 9 2-blade propeller. Later this was replaced by an Autoprop.

Start early
Changing inboard engines is not a simple project. If you are very adept at major projects, if you are a good mechanic, if you have lots of time and patience, and most of all if you enjoy working on boats and this type of challenge, then you should start doing your homework and putting together a loose-leaf notebook.

Begin buying the necessary parts months in advance. I started buying my conversion gear six months before the start of my project, and that was not too soon. I discovered that the delivery of a new prop would take six weeks and the longer prop shaft would take almost as long, even though it was always: “I’ll have it for you next week.”

It’s important to learn as much about your new engine as possible before you start the project. There are many engine distributors who offer one- or two-day seminars specifically targeted at owners of auxiliary engines. Mack Boring & Parts Company, which sells Yanmar engines and parts, has one- and two-day owner seminars on Yanmar engines that are invaluable. These classes are given at Mack Boring locations in Union, N.J., Wilmington, N.C., Middleborough, Mass., and Buffalo Grove, Ill. The classes cover the theory of operation, explain all the parts of your new engine, cover routine maintenance, and include a hands-on session that gives participants the opportunity to do routine maintenance on the engine they will actually own, including adjusting and bleeding it.

Incidentally, one item that is invaluable in setting up the placement of a new engine on the rebuilt bed is an engine jig, which can usually be rented from the engine distributor. The jig consists of light-weight metal framework that locates the proper position of the engine mounts and shaft alignment. It copies the exact size and angle of the real engine and can be aligned with the prop-shaft coupling, revealing whether there has to be any change made in the engine bed or mounts long before the engine is swung into position.

The alternative to the engine jig uses another type of alignment method that will be discussed further in Part 2 of this series, which will run in the November/December issue of Good Old Boat.

Installation manuals
Nearly all engine manufacturers have comprehensive installation manuals that are essential for the do-it-yourselfer. These manuals, which should be part of your repowering notebook, have step-by-step installation instructions, including alignment procedure; wiring diagrams; engine specifications, dimensions, shaft and prop recommendations; and fuel, water, and exhaust-hose requirements. It’s also a good idea to purchase a service manual for your engine. It will be a handy reference for the future, and it gives some installation information that isn’t necessarily shown in the installation manual.

New engines come with their own instrument panels. If you have an instrument panel recess in your cockpit, especially one that is molded into a fiberglass boat, make sure that the new engine’s instrument panel will fit into the old recess. If it won’t, it might be tempting to try to use the old panel with the new engine, but this usually is asking for a lot of headaches, including replacing the tachometer, oil and temperature gauges, and wiring. Some manufacturers have several panel options of different sizes. Yanmar, in their GM series for auxiliaries, have three control panels of varying sizes and options.

Repowering a boat from a gasoline engine to diesel power needs extra consideration. Diesel engines of equivalent horsepower are usually physically larger than their gasoline counterparts. You may find, however, that the Atomic 4 in your boat has much more horsepower than the diesel you will replace it with. Many smaller boats were powered with an A4 and a direct-drive transmission. Only half the engine speed range, and thus roughly half the horsepower, was used. These direct-drive boats were equipped with very small props.

Bed modification
Even if you’re sure an appropriate diesel will fit in the engine compartment, you’ll probably need to rebuild or modify the engine bed. Consider the maximum-diameter prop that can be fitted to your boat and still have the required tip clearance. Match this against the prop that the new engine will need. Not all gasoline tanks and fuel lines are compatible with diesel fuel and, as mentioned previously, a fuel-return line will also have to be added. The primary water-separator/ fuel filter will also need to be replaced. In some cases, the prop shaft may have to be increased in size which, in turn, means a new stuffing box.

Most of us have a pretty good idea how much power we need, based on the performance of our previous engine. The old rule-of-thumb for auxiliaries of 2 hp for every 1,000 pounds of displacement is usually pretty good. If you really want to get into the calculations, then consult Dave Gerr’s Propeller Handbook or Francis Kinney’s Skene’s Elements of Yacht Design. Another source of information is at http://www.boat diesel.com on the web. This site, which provides a wealth of information on diesels, charges a $25 membership fee. If you click on Propeller/Power/ Shaft Calculations, you can find the proper shaft size, the power required for a given hull, and the recommended propeller specifications.

Be sure to check the alternator options available for your new engine. If your electrical consumption is high, as is the case with a refrigeration system or a watermaker, be sure to specify the appropriate alternator when you order the new power plant.

Engines for an auxiliary must, above all else, be reliable. When selecting the manufacturer of your new engine, do your homework. Talk to other sailors who have had an engine replacement recently and get their opinions. Get information from various engine companies and local marine mechanics, check out these engines at boat shows, and talk to the manufacturers’ reps.

When you’re finally back in the water with a new engine, you’ll feel much more inclined to take that long cruise you’ve been delaying for years, safe in the knowledge that you have a new power plant of high reliability for which parts are readily available.

Replacing the power plant

Tips on how to extract the old one and install the new one
by Don Launer

In the September/October issue of Good Old Boat, we discussed the decisions to be made when the inevitable day comes that your power plant needs to be either rebuilt or replaced (Repowering, Part 1: The decisions). In either case, the engine will have to be removed from the boat. Once you have decided that engine replacement is the way to go, and you have made the decisions laid out in the previous article, the actual engine replacement can begin.

Although the photographs and text detail the specific procedures on our schooner, Delphinus, most of the problems we encountered generally apply to all sailboats. We were replacing a 1980 saltwater-cooled Volvo MD-11C diesel that had a left-hand prop with a new 2001 freshwater-cooled Yanmar diesel designed for a right-hand prop. Whether the propeller is left-hand (counter-clockwise) or right-hand (clockwise), is determined by the direction the propeller turns, as viewed from the stern, when the transmission is in "forward." (Usually, the crankshaft of the engine itself turns in the opposite direction from the propeller shaft). Although the Yanmar that I decided to use has slightly greater horsepower than the old engine, its physical dimensions - height, length, and width, as well as weight - are all less than that of the old Volvo. This is common with replacement diesels, due to improved diesel design within the last couple of decades.

Before the old engine can be removed, all of its connections to the boat must be taken off: the exhaust, water lines, fuel line, control cables, and electrical connections. After everything connecting the old engine to the boat has been disconnected, the screws or bolts holding the engine mounts to the beds can be removed, and the engine is ready to be hoisted out of the hull.

Difficult removal
It would be nice to think that the old engine can be easily removed. In point of fact, in fiberglass boats, the engine was often installed before either the deck mold and/or the interior mold were put in place - a bizarre construction concept. As a result, some engines have to be removed through the cabin, while others can be taken out through a removable cockpit panel. Our boat has a removable cockpit panel, since the centerboard trunk, on which the schooner-rig's mainmast rests, is just forward of the engine compartment doors and eliminates this possibility.

Sometimes an engine can be removed more easily in sections, such as by first removing the transmission, and sometimes the old engine can only be removed by lifting it out by one end. Often, discouragingly, the only way is by cutting out a section of fiberglass. The same problem may hold true for wooden boats, where major woodworking reconstruction is sometimes necessary to get the old engine out of its cocoon.

In order to take out our old engine, a section of the interior aft countertop in the cabin had to be cut away. In addition, the Volvo engine and its transmission were longer than the cockpit hatch opening, and the old engine had to be canted at a 45-degree angle to get it out of the hull. I had planned to remove the old Volvo's transmission, which would reduce the overall length and make getting the engine out much easier. However, in trying to do this, I discovered one of the four bolts holding the transmission to the engine was frozen in place. Its head was stripped, and nothing I could do would free it. I probably could have drilled it free, but its location, underneath the transmission in a nearly inaccessible spot, made this almost impossible.

Yard expertise
When it's time to remove the old engine, the obvious choice is between doing it yourself or having the marina do it. Most boatyards have done this job many times before and have the equipment and expertise to do it efficiently. If you are hoisting the engine out yourself, it goes without saying that you must make sure your hoist can handle the weight. For an engine that has to be removed through the cabin, special equipment, which most marinas have, is necessary.

With the old engine gone, the engine compartment can now be cleaned up of old oil and grease. Although there are many good (and expensive) marine degreasing products available, you might want to consider using Dawn dishwashing soap, which does the job as well as or better than anything else. It's also great for cleaning up greasy hands and is biodegradable. Once the engine compartment has been cleaned and becomes more habitable, the old wiring, plumbing, and exhaust system can be removed and/or reconfigured for the new engine.

Although our installation was done in the spring of 2002, we purchased our new engine in the fall of 2001. This was done for two reasons: first, we purchased it just before a 5-percent price increase; second, having the engine on hand for several months before the installation was to begin enabled us to check its dimensions, measure the sizes of the water hoses, exhaust hose, fuel hose, fuel-return line, and water-heater heat-exchanger hoses, and purchase the necessary hose diameters and lengths with the assurance they would all fit when the time came for the hook-ups.

New propeller
Our old Volvo diesel had a left-hand prop, but our new Yanmar has a right-hand rotation, so early on we bought a new right-hand propeller (a good thing, since there was a six- to eight-week delivery schedule). We also needed a new, longer prop shaft, due to the shorter length of the Yanmar, as well as a flange coupling for that shaft that would be compatible with the flange on the transmission of the Yanmar. It's probable that the flange coupling on your old shaft (as with ours) will be rusted and frozen in place so it cannot be removed by sliding it back out of the hull. Fortunately, once the old engine is out of the way, the old prop shaft and its coupling can be easily removed by sliding it forward, out into the empty engine compartment. The chances are that the rubber hose on your shaft-log hasn't been replaced in a long time, so now's a good time. Better yet, consider a dripless coupling, which is easily installed once the old rubber hose and packing gland have been removed. (I installed a packless shaft seal manufactured by PYI, Inc.). This investment will pay dividends in the future by eliminating the awkward contortions required when readjusting the packing nuts, as well as providing a dry bilge.

With the old engine out of the way, this was the perfect time for easy removal of the old water heater (long overdue), which was in the engine compartment, and the installation of a new one. The new Raritan water heater, with engine-water heat exchanger and 120-volt immersion heater, was of similar size to the old Raritan whose steel case was rusting away. The new Raritan heaters now have plastic cases and more insulation.

New engine bed
Since it's probable that your new engine will be smaller than the old one, the engine bed will have to be rebuilt. This may mean tearing out the old stringers and installing new ones. If you have a fiberglass boat, the new beds will have to be built up using fiberglass and epoxy. If you're not well acquainted with fiberglass work, it's probably a good idea to leave this job to a professional.

We were fortunate that the mounting width of our new Yanmar was exactly 3/4-inch less than that of the old Volvo. So we used two heavy-duty, 3/8-inch thick, 3-inch by 3-inch marine-grade aluminum angles bedded in 3M 5200 and through-bolted to the old fiberglass-and-oak bed. These heavy-duty aluminum beds ensured that when the mounts were installed they would be true and level.

In nearly all engine conversions, the different size of the new engine and the rebuilt engine beds will probably mean that the old oil-drip pan will no longer fit and a new one will have to be made. I constructed the new one out of fiberglass and lined it with a replaceable sheet of Oil-Zorb.

Most auxiliary engines are installed on mounts that have heavy-duty rubber shock absorbers between the top threaded stud that is bolted to the engine, and the base, which is bolted to the engine-bed. Usually there are four mounts, near each corner of the engine. The mounts use nuts and washers on the studs, which are used to adjust the engine up and down and lock it in place. (The bottom nut that actually supports the engine is called the "jack nut.") The bases of these mounts have holes for the mounting bolts, and one of the two holes is slotted. These slots allow the engine to be moved sideways slightly so it can be lined up perfectly with the propeller-shaft coupling.

Different mounts
When preparing to install the engine mounts, be aware that for many auxiliary engines the engine mounts are different for the front and rear of the engine or for the port and starboard sides due to the different weight and dynamic loads imposed on them. These shock-absorbing mounts usually have a number molded into their rubber, which indicates the rubber's hardness. For engines that require different mounts fore-and-aft or side-to-side, the installation manual will specify their required locations. During the installation, and in the future, keep oil from getting on the rubber sections of these mounts, since it can cause the rubber to deform and swell, eventually resulting in incorrect engine-to-shaft alignment.

Shaft alignment
If you are installing a new engine and retaining your old through-hull shaft log, the engine-coupling flange will have to be lined up perfectly with the flange on the propeller shaft. The engine bed must be horizontal athwartships, with an inclination angle within the allowable limits of the engine-mount adjusting nuts. Most manufacturers' installation manuals give detailed descriptions on this alignment procedure, which usually is one of two types or a combination of both.

To determine the centerline of the propeller shaft, its height, and its inclination, a pointer is bolted to the propeller-shaft flange, with a string coming out at shaft-center. This string has a fish-weight tied on the free end, and this weight goes over a piece of wood that is temporarily clamped to some point farther forward.
When the propeller shaft is rotated, this free-end piece of wood is moved until the pointer circles the string evenly. The position of this string now becomes the centerline extension of the propeller shaft, from which engine-bed construction and engine placement measurements can be made. Installation instructions recommend that this pointer and string be fastened directly to the propeller-shaft flange, rather than to an intervening flexible coupling or "Drive-Saver," which could introduce an error.

Although the construction of a new engine bed and alignment of the new engine can be done directly from measurements to this centerline string, a much easier and less time-consuming way of creating the new engine bed and aligning the engine is through the use of an engine-bed alignment jig. These jigs can sometimes be rented from an engine distributor for your particular engine, greatly simplifying the engine-mount placement measurements. As in the previous step, the string from the center of the propeller shaft passes through alignment holes in the jig, and the engine mounts, which are bolted onto the jig, can be located perfectly on the new engine bed, with the assurance that the propeller shaft flange and the engine transmission's flange will match very closely when the new engine is installed.

Check tolerances
Once the engine mounts have been fixed to the new bed and the engine has been installed, it's time to check the coupling tolerances between the two flanges. Mismatches between the two surfaces (the flange on the engine and the flange on the propeller shaft), should be compensated for by adjusting the motor mounts, which can move the engine up or down an inch or more. The slots in the engine mounts also allow you to move the front or rear of the engine to one side or the other to match up the two flanges. Using a feeler gauge around the periphery between the two flanges, you can adjust the engine mounts so that the two flanges mate to within 1/1,000 inch. Note that these tolerances should be checked between the flanges themselves, and not with an intervening flexible-coupler or "Drive-Saver." Once the two flanges match perfectly, the flexible coupling can be added, and, with everything lined up, the bolts on the flanges are tightened. This shaft alignment is vital for preventing Cutless-bearing wear, transmission damage, and vibration.

A new engine installation is usually performed on land. It's important to realize that when a shaft alignment is done on land, the alignment can change after the boat is back in the water with the mast stepped and the rigging tensioned. On a new engine, this alignment can also change during the first few days or weeks as the rubber in the new engine mounts compresses to its final size. Some installation manuals suggest that the jack nuts on the engine mounts be raised one turn above perfect alignment to compensate for this inevitable rubber compression.

Anti-siphon valves
If the raw-water output from the engine that goes into the exhaust-mixing elbow is below or close to the boat's waterline (when level or heeled over), it's imperative that an anti-siphon valve be added. Without this valve, after the engine is turned off, water can continue to siphon into the exhaust system, eventually backing up into the engine itself and causing major damage. The anti-siphon valve allows air to enter the system when there is a suction, which occurs during siphoning, but the air valve closes when pressure is present, as when the engine is running.

There are many types of anti-siphon valves, made from various materials. Some have connections for a small tube that allows the few drops of overflow water to go directly to the bilge rather than drop on top of the engine. This can prevent fresh water or corrosive salt water from attacking the top of your new engine. This overflow tube has another advantage: by blowing into the tube you can determine whether your siphon-vent is clogged or stuck.

Engine connections
When the engine is in place, it's time to connect the fuel supply line, fuel return line(s), water system, exhaust system, electrical system, and control cables. If hoses, control cables, and wiring in the engine compartment haven't been changed in a while, now is a good time.

When it comes to determining sizes of fittings and machine screws on your new engine, you must realize that there are three primary measuring systems in use around the world, metric standards, USA (inch) standards, and British (inch) standards. As the world moves toward metric standards, sailboat power plants will be increasingly built to these standards.

Fortunately there are now many places in the United States that can supply metric tools and machine screws. But even on an engine built to metric standards, there are anomalies. Strangely, most countries that use metric standards, both in Europe and in Asia, use the British (inch) standard for measuring pipe fittings. I discovered this contradiction when installing my metric system Yanmar engine. Almost everything on this engine is metric, but the threads on the engine for the water fittings that feed the heat-exchanger for the on-board hot water tank are British (inch) standard.

British standard pipe-fittings come with either a cylindrical (parallel) thread or with a tapered thread. My Yanmar engine demanded a fitting with British standard tapered threads (which are designated in Japan, and in the Yanmar shop manual as "PT." Thus, a designation of "PT-3/8" (as shown in the shop manual) means that the fitting is a British standard 3/8-inch tapered pipe fitting.

No fittings
The Yanmar engine has two plugs that can be removed to accept the hose-fittings for the hot-water tank's heat exchanger. Although Yanmar sells the hose adapters that fit these threads, the fittings had been on back order for several months and were not available when I was installing my new engine.
Luckily, I discovered Maryland Metrics http://mdmetric.com/ on the Internet. This company sells a wide range of metric tools and fittings as well as British standard and American standard pipe fittings and adapters. They had adapters in stock that went from the British standard tapered 3/8-inch pipe thread (PT-3/8) on the Yanmar to a U.S. standard 3/8-inch pipe-thread, which solved the problem nicely. Once I had converted to the U.S. thread, elbows and hose adapters were readily available.

Incidentally, Maryland Metrics has a wonderful website describing the threads in all three systems. They also have a huge inventory of nuts, bolts, parts, adapters, and metric tools. For my very small order for two adapter fittings, they couldn't have been nicer or more cooperative in helping me solve my problem.

Final preparations
When everything has been completed, it's time to fill the crankcase and the transmission with the oils specified by the manufacturer. Before doing this, however, check the oil levels, since many manufacturers supply the new engine with oil already in the crankcase and transmission. This is an especially important check with diesel engines, since too much oil in the crankcase can cause a runaway engine. With freshwater-cooled engines, fill the engine's heat-exchanger with a 50/50 solution of water and anti-freeze, as per the manufacturer's instructions. Many manufacturers recommend that the water used with the anti-freeze be distilled water, since there's no telling what chemicals might be in city water.

For diesel engines it now will be necessary to bleed the fuel system, otherwise the engine won't start. This bleeding is usually done at two places in the fuel supply system as well as at the injectors of each cylinder. These locations will vary from manufacturer to manufacturer and will be described in the owner's manual. Once you have located these points it's a good idea to paint all of these bleed-points with white paint. It will make it a lot easier to locate them at some time in the future when you accidentally run out of fuel and you have to do a bleeding job under less than ideal conditions. It will also make it easier to bleed the system each time you change the engine's fuel filter.

Check liquid levels
After the engine is run for its first test - no more than a couple of minutes - the levels of oil in the crankcase and transmission, as well as the cooling-water level, must be checked. As the fluids are distributed throughout the engine and heat exchanger, levels can drop.

Most diesel manufacturers recommend that if your engine hasn't been used in a few days, it's a good idea to pre-lubricate it before starting. For engines that have a manual Stop control, this can be done by holding out the Stop control while turning the engine over with the starter for about five to 10 seconds. If the engine hasn't been used in a really long time, wait 30 seconds and repeat the procedure. This will distribute oil throughout the engine. It's also a good idea, after starting, to let the engine run at mid-range for about five to 10 minutes before putting it under load.

When stopping, let the engine cool down by idling it for about five to 10 minutes, then, just before stopping the engine, give it a burst of power to blow out any carbon in the cylinders.

When our boat was finally back in the water after the new engine had been installed, I was hoping that it would be a calm day for the one-hour motor-trip from the marina to our home dock, but this was not to be. When I came out of the marina I had 20 knots of wind right on the nose and a high chop. It was literally a shake-down cruise. But the new installation performed flawlessly, and I was able to head home at hull speed.

This new engine installation should be good for the next 25 to 30 years. I just wish that I could be good for that long.