Engine dependable

From Ocean Navigator #99
July/August 1999
Sailors like to think that they and their boats can do what Joshua Slocum did in his ketch Spray: sail tens of thousands of miles with only the wind for power. The fact that the majority of voyaging sailboats are equipped with diesel engines is evidence of an important truth. For most of us, the success of a voyage is highly dependent on our engines. This is especially true on extended voyages. In addition to propelling us through calms, the electrical system, watermaker, and refrigeration depend upon a properly operating engine.

Simply giving an engine a thorough cleaning before a voyage can reveal small leaks that could later develop into more serious problems with seals and gaskets.
   Image Credit: Buell Heminway

Engine malfunction on a short voyage is an inconvenience. Failure on a long passage can be annoying or it may create a critical situation. Ensuring that your engine is dependable must begin with careful inspection and service well before the planned departure date.

Minor operating faults that were tolerated during short trips must be eliminated before beginning a long voyage. Do the work with the same attitude you would have if you were inspecting a boat you were considering for purchase. Fix every known or suspected fault now.

Pre-departure evaluation

Begin by cleaning the engine, taking care not to spray water on the alternator, starter, wiring harness, or electrical connectors. Many major engine problems begin with small weeps and leaks best seen on a clean engine. Use a bright, 12-volt inspection light and a piece of clean white cloth (you will need the 12-volt light during your voyage).

Evaluate your engine’s performance.

· Does the engine start promptly?

· Does the voltmeter or ammeter show that the starting battery is being properly recharged?

· Is there excessive white smoke during warm-up? (A moderate amount of white smoke on start-up may be normal, especially when the temperature is low.)

· Is there a significant amount of blue smoke when the engine is warm and operating under load at a moderate power setting?

· Is there significant black smoke when operating the engine under load at full throttle?

White smoke after warm-up may indicate water in the fuel or an internal water leak within the engine. Blue smoke may indicate excessive oil in the crankcase or excessive wear of valve guides or piston rings/cylinder bores. Black smoke may indicate a clogged air cleaner, too large a propeller, or misadjustment or mistiming of the fuel-injection system.

Using your bright inspection light, carefully examine the engine while it is running. Check for any signs of fluid leaks, particularly at the small drain holes that are usually found on the bottom side of the fresh- and saltwater cooling pump castings, just behind the V-belt. Water leaking from these holes indicates a failed water pump seal. Listen for unusual noises. A grinding noise from the alternator may indicate that the bearings are nearing end of life. Check the operation of all engine gauges. Evaluate how long it takes for the engine to reach normal operating temperature (usually at least 170° F for freshwater-cooled engines).

· Does the engine temperature remain below approximately 190° to 200° F when operating under load at full power? Failure to promptly reach normal temperature may indicate a cooling system thermostat that is stuck in the open position. Too high a temperature may indicate that the thermostat is not opening fully or that the heat exchanger needs cleaning.

· Does the engine shift into and out of gear easily?

· Does the engine shutdown work properly?

Examine the engine mounts for signs of deterioration. Replace any mount that appears soft or if the rubber is becoming separated from the metal parts. Resilient rubber mounts compress after a period of use and may need to be readjusted by checking the alignment between the engine shaft and the propeller shaft. Examine the oil in the transmission for any signs of discoloration or a burnt odor. Check the shaft stuffing box for signs of excessive leakage or, in the case of bellows-type seals, any deterioration of the bellows.

If examination of all of the items above raises any question in your mind, have the engine checked by a mechanic who is familiar with the type of engine in your boat.

Pre-departure service

Make a list of every service action in the engine maintenance manual. Check the required actions against the following brief list:

· Change the lubricating oil when the engine is still at normal operating temperature, using the manufacturer’s recommended grade of API-approved oil.

· Change the oil filter using the original manufacturer’s brand of filterall filters advertised as being suitable for an engine may not provide the degree of protection built into the manufacturer’s original equipment part.

· Change the fluid in the transmission. Be sure to use the correct fluidsome transmissions use engine oil, others must be serviced with automatic transmission fluid (ATF). Be careful not to overfill either the engine or the transmission. When checking the ATF level used in Hurth-type transmissions, the rim of the screw-in dipstick should rest on the circumference of the threaded hole in the gearcase; it should not be screwed in place.

· Change the fuel pre-filter element, and drain the water trap in the prefilter.

· Change the final fuel filter. Carefully examine the pre-filter element for signs of water or the black or green slime that indicates the presence of algae or bacteria contamination in the fuel tank. If there is any evidence of contamination have the tank drained and the tank and fuel lines cleaned.

Check the operation of the electric or hand fuel-priming pump. Verify the operation of the engine-mounted mechanical fuel-lift pump by slightly loosening the fuel delivery line from the pump and then operating the pump’s manual actuating lever. Fuel should flow from the loosened fitting. Pump diaphragms have been known to fail silently. The problem becomes evident only when the engine must draw fuel from a nearly empty tank.

If your engine does not have a fuel prefilter such as a Racor, install one, or even two, with change-over valves so that you can service a blocked filter without stopping the engine. The fuel you buy during your voyage may contain more contaminants than you are used to encountering at home. Be sure to carry a gallon container of clean diesel fuel for use in refilling the prefilter following an element change. The filter element used in the prefilter should be rated to stop larger-size particles than the final filter. Using too fine an element in the prefilter will lead to premature element replacement, inconvenience, and added cost. Filter elements are typically available in three ratings: two micron, use as final filter (Racor brown end cap); 10 micron, use as primary or secondary filter (Racor blue end cap); and 30 micron, use as primary filter (Racor red end cap).

If your engine is turbocharged, inspect the turbine blades on both the exhaust and air intake sides for damage. Over time, turbine blades become contaminated and lose efficiency, and they should be washed. Engine manufacturers usually recommend the interval between washings and the type of solvent to be used.

Install new V-belts. Readjust tension after five hours of engine operation. Clean and service the air filter. Check the fuel-control cable attachments, shift cable attachments, and the engine stop cable or solenoid.

Check the batteries and battery switches. Clean any corrosion and re-coat with anti-corrosion grease. If possible, check all batteries using a quality hydrometer if possible. If specific gravity differences between cells in a battery exceed 0.050, perform an equalization charge and recheck. If readings still differ, consider installing new batteries.

Set up a maintenance record book

Prepare a maintenance record book. Record date and engine hours for: oil change, filter change, fuel filter service, zinc inspection and replacement, gear box oil change, V-belt replacement, and fuel consumption. If using flooded-cell batteries, record the specific gravity for each cell in each battery along with the date of the check. Continue to make such checks at least monthly (weekly is better). With the battery record, a failing cell can be identified before the use of the battery is lost, with possible unhappy consequences for the remainder of the battery bank. If you are using gel cell or other recombinant battery types (including absorbed electrolyte or AGM batteries) you will have to rely upon your battery monitor system or digital voltmeter to gauge battery condition. Record the voltage readings.

Unless it was replaced very recently, install a new raw-water pump impeller. Remove and inspect all zinc anodes in the engine-cooling system. Unless in virtually new condition, replace with new zincs. Note part numbers and include spares in engine spares kit. Replace the freshwater coolant with an antifreeze mixture that is known to be compatible with your engine. Not all coolants used in vehicles are safe for use in diesel engines. Plain water is highly corrosive and must never be used in the cooling system. Antifreeze or diesel engine coolant must be used at all times. If the antifreeze or diesel coolant additive must be mixed with water, use distilled water. Check the engine cooling water seacock. Be sure the seacock can be opened and closed easily and that the flow of water is fully stopped when the valve is closed. Check the seawater strainer and the strainer basket for corrosion. Replace the basket if it is corroded.

Check every hose on or adjacent to the engine for undue softness or other signs of deterioration. Replace any that are in any way suspect. Pay particular attention to molded rubber parts, such as the end caps used on many heat exchangers. These can fail without warning, dousing the engine with salt water. Carry spares for every molded rubber part on the engine or transmission. Check every hose clamp. Replace any which show any sign of rust or corrosion. Consider using the type of clamp that has an embossed screw-thread pattern in the band instead of the more common type in which the screw threads are created by perforating the band. The embossed clamps are often identified as suitable for use in acid environments. They cost more but fail less often. Don’t overtighten hose clamps. They are intended to compress the hose against the barb, not cut through it.

The exhaust system must be checked for signs of corrosion, deteriorated hoses and hose clamps, and overall structural integrity. Most sailboat exhaust systems use water-lock mufflers and are equipped with anti-siphon check valves. These valves can fail silently, creating the risk of entry of sea water into the engine’s exhaust manifold if the engine is stopped when the exhaust outlet is below the water. Remove and test the valve. It should close when pressure is applied to the end that connects to the exhaust system and open when a slight vacuum is applied. Replace it if there is any doubt about its proper function. In the event you ever have to motor the engine with the starter for more than about 60 seconds, close the seawater seacock to prevent cooling water from overfilling the water lock and finding its way into the engine’s cylinders. Open the seacock as soon as the engine starts.

Check the propeller and shaft for signs of wear, erosion (due to electrolysis), and excess play in cutlass bearing. Replace shaft zinc unless it is in virtually new condition. Note date of replacement of shaft zinc and engine zincs in maintenance book for future reference.

When the service actions are complete, recheck everything listed above in your pre-departure service list.

Spares provisioning

Although you hope that your spares provisioning will allow you to evade Murphy’s law, which promises you will have forgotten something you need, you will not likely avoid O’Brien’s law, which states that Murphy is an optimist. However, it’s worth trying. Begin by obtaining copies of the engine manufacturer’s operation, service and maintenance manuals for your engine. Buy a full-service gasket kit for your engine. Fuel-injection lines can fail due to metal fatigue. Buy a spare set, including the fuel return lines. When you receive them, check them against those on your engineon occasion, part numbers are confused. Although modern multi-stage fuel filters have greatly reduced injector malfunctions, you may encounter contaminated fuel during your journey. Carry a spare injector. Buy spares for any special size of molded hoses and lengths of any standard hose, including those that run to and from your domestic water heater. Lay in a supply of water pump impellers and whatever gaskets or O-rings are needed to reseal the pump. Consider carrying a spare raw-water pump and, if the engine is more than five years old, a spare freshwater pump. You will need a couple of sets of V-belts. Spare packing for the prop shaft stuffing box should be on hand, precut to size and ready for installation.

The engine’s battery-charging alternator can be a particularly critical element in the success of a voyage. Alternators are remarkably reliable devices provided they are kept dry, used often, and never disconnected from the batteries when the engine is running. However, as with any other similar device, they can fail. A spare alternator, which may be a remanufactured unit purchased for about $100, can be worth a great deal if the main unit malfunctions. Alternatively, you may wish to have a second alternator mounted on the engine, with its V-belt in place and wired to permit it to be switched on whenever desired. Dual alternators can be every bit as important as having more than one battery. Even with dual alternators, you may wish to carry a spare parts kit for the alternator for possible use if repairs are needed in some out-of-the-way place.

Regardless of the type or number of alternators installed, they should be equipped with external voltage regulators in parallel or in place of the typical built-in regulator. Built-in regulators are fine devices; however, they are designed to properly charge batteries that are at about the same temperature as the engine/alternator. Sailboat batteries are usually located in a much cooler environment than the engine. Under these conditions the temperature compensation circuit in the built-in regulator will prevent the batteries from being fully recharged.

When an external regulator is installed, it may be useful to have an emergency switch installed that when turned on will connect the alternator’s field winding directly to the 12-volt battery bus. Used in the event of failure of the external and internal regulators, this switch will force the alternator to supply its maximum output current, rapidly recharging the batteries.

Carry a supply of lubricating oil and filter elements for all filters. Be sure to carry more fuel filter elements than you believe necessary. Spare fluid for the transmission should be on board. Tubes of gasket-forming material, including Permatex High-Temp RTV Silicone Gasket Maker, should be part of the spares kit. A special type of RTV sealant, Three Bond Liquid Gasket, Yanmar part number 97770-01212, which is specifically designed for use on hot and oily surfaces, can be very useful in stopping small oil weeps and leaks.

When doing the spares provisioning, remember to include the tools you may require to do any needed service. Wrench sets to match every fitting on the engine and transmission should be on board. Include sets of long and short Allen wrenches, nut drivers of sizes to fit any small electrical terminal nuts, flat-blade and Phillips screwdrivers (the latter type with hardened points), and torx drivers if any of this type fastener are used on your engine or any of its accessories. It is also worthwhile to carry spare machine screws, bolts, flat and lock washers and normal and self locking nuts of the sizes and lengths used on the engine or its accessories. Losing a nut into the bilge when no spare is on board can ruin your day.

Keeping it going

You have done your job. When you leave port the engine is running perfectly. Now, you want to keep it that way. The effort begins with careful inspection of the engine before restarting it after a period of non-use and periodic inspection while it is in operation. The bright inspection light you bought or made for use in the pre-departure inspection will come in handy. Installing some bright, permanent lighting around the engine can be a great aid in making the necessary inspections. Do as they do on luxury motoryachts: carry a pair of hearing protectors. Engines are noisy beasts, especially close up. It is remarkably easier to give the inspection the attention it requires if your ears are not being pounded by the din of the engine. Operating engines should be checked about once every two to three hours. It’s better to catch the problems while they are small, not when they announce their presence with the sounding of an alarm.

Given clean fuel, clean air, clean lubricating oil, and an adequate cooling system, most diesel engines will run longer than all the hours in any voyage you are likely to undertake. Contaminated fuel is a major risk to engine happiness. Fuel can be contaminated before delivery or it may become contaminated after coming on-board. If fueling at a place where quality is in question use a prefilter connected to the pump nozzle so that contaminants can be stopped before the fuel reaches the tank. Various forms of home-built open-trough devices can be built to allow visual inspection of fuel before it flows into the tank. Always add a biocide to the fuel when filling the tank. Some sailors have found the addition of a magnetic fuel conditioner unit, such as the New Zealand-made DeBug, worthwhile in eliminating bacteria and algae problems. If possible, plan any necessary refueling at places where quality may be in question so that you need refill only one tank at a time. Should the fuel taken on turn out to be causing problems, you can switch back to the known good fuelafter changing all the fuel filters.

Lube oil and filter changes are important. However, extended hours of engine operation while on a passage can be tolerated without stopping to do an oil change in the middle of an ocean. The engine will be kept warm, if not hot, and the oil contamination that occurs when the engine is idle for long periods of time will not occur. All fluid levels should be checked at least daily. Coolant levels on many engines can be checked by way of the transparent overflow bottle fitted to the coolant header tank.

Observe the recommended service intervals for valve lash check and adjustment. If the voyage is really long it may be desirable to have a qualified person check the injection-system timing. Gear wear can cause some variation over time.

When sailing, remember to lock the prop shaft so that it cannot turn. If the boat has a Hurth-type transmission (it will be filled with ATF fluid, not oil) the shaft can be locked by placing the gear lever in the reverse position. If this technique is used, remember that to start the engine you will either have to bring the boat to wind and stop all forward motion before shifting into neutral, or start the engine with the shifter in reverse, moving it to neutral as soon as the engine is running.

Hurth-type gear boxes cannot be safely shifted out of reverse when there is any forward motion working on the prop. Allowing this type of transmission to free-wheel for protracted periods of time is not advisable. It can cause excessive wear on the clutch packs in the transmission.

Transmissions that use lubricating oil frequently have cone-type clutches. Some of these may lock if shifted into reverse. In the event they do not it is advisable to fit a separate shaft lock to the prop shaft. Allowing the prop to free-wheel may cause excessive wear to the aft bearing in the transmission, which may be lubricated by an internal oil pump that operates only when the engine is turning the transmission input shaft. If an external shaft lock is used, be sure that there is a clear indication that it is engaged. Trying to start an engine with a locked shaft can cause problems if the transmission happens to be in gear.

Contributing editor Chuck Husick is a sailor, pilot, and Ocean Navigator staff instructor.

By Ocean Navigator