Lessons from the Oil Sump Analysis of used engine, transmission, and hydraulic oils can yield invaluable diagnostic data to help predict and avoid mechanical failures. Text and photographs staple of any good yard’s mainte- and analysis. It’s unlikely they would A nance schedule for each boat make such an investment unless it by Steve D’Antonio in its care is to change the oil and offered a tangible return. fi lters based on use or regular seasonal The diagnostic information that fl uid service. As a result, boat owners analysis can provide includes abnor- already spend hundreds if not thou- malities such as excessive bearing sands of dollars on engine and wear, failed or clogged air fi lters, fuel- hydraulic oil and fi lter changes every injection system malfunctions, fuel year. But most of that used oil is dilution, increased lubricant acidity, unceremoniously disposed of along incorrect oil weight, glycol/coolant with a wealth of information that contamination, diminished corrosion could be extracted from it at modest resistance, leaking heat exchangers, expense by participation in an oil- analysis program. Commonly referred to as predictive and condition-based maintenance, studying fl uid drained from engines, generators, transmissions, hydraulic stabilizers, thrusters, and steering and cooling systems can frequently help identify problems in mechanical com- Above—This magnetic drain plug and ponents. Modifying maintenance pro- the slurry of metal and oil it has tocols based on the results of oil A diesel engine after a catastrophic captured clearly signal the demise of tests can prevent catastrophic failures. meltdown; the aluminum at the top a transmission. Predictive maintenance Commercial industries from manufac- of the cylinder, once molten, is now informed by a comprehensive oil analysis turing and mining to oil drilling and solidi ed. Regular oil analysis would program could alert owners and service transportation, as well as military likely have revealed, among other crews to problems long before they and research institutions, spend millions things, elevated levels of aluminum reach this critical stage. of dollars annually on oil sampling and iron that preceded the failure. 62 PROFESSIONAL BOATBUILDER and failed head gaskets. In short, the analyst with less-valuable information, or lubricity, impairing its perfor- information gleaned from regular and makes determining the cause of a mance as a lubricant. By applying analysis of engine, generator, and problem more challenging and less elemental and spectroscopic analysis, transmission gear oil, as well as certain. That said, a single sample a laboratory can determine how much hydraulic and cooling system fluids, is and the report it generates are still of any particular contaminant is in a easily obtained and too valuable to valuable. This is particularly true of lubricant sample. An inductively cou- forgo. pre-purchase surveys and trouble- pled plasma (ICP) test can isolate and shooting in instances when no analysis identify 24 metals likely to be found Oil-Analysis Basics has been carried out over the life of in engine, transmission, or hydraulic Tribology is the science of interact- the vessel. oil. The presence of some of these ing surfaces in relative motion, includ- For the owner, captain, or service metals even in a single test can indi- ing the study of lubrication, friction, yard responsible for the long-term cate excessive wear and impending and wear. Tribological wear occurs as care of a modern boat, establishing a failures (see chart on page 69). High a result of relative motion, which is regular oil-analysis program allows levels of aluminum, for instance, precisely what takes place within the the application of CBM rather than a could be from piston scuffing or internally lubricated portions of all scheduled maintenance program. This broken thrust washers, while high marine internal-combustion engines, approach is beneficial for virtually any copper content may indicate exces- generators, transmissions, and hydrau- engine, gear, or hydraulic system; and sive valve-guide or shell-bearing lic systems, including stabilizers, if an engine or hydraulic system uti- wear, or slipping clutches. thrusters, windlasses, cranes, steering lizes bypass filtration, which allows it Other metal and mineral contami- units, and transmissions. to operate under an extended oil nants are introduced from outside the Oil analysis has been around about change regimen, then oil analysis lubricated system. These typically half as long as mass-produced internal- becomes mandatory. (Bypass filtration include silicon dioxide and aluminum combustion engines. In the United systems, with filters as fine as 1 oxide (otherwise known as dust or States, credit for adopting this diagnos- micron, are added to engines to treat dirt), which can enter through dam- tic and maintenance tool goes to rail- a small portion, typically about 10%, aged air filters or crankcase breathers; roads in the early 1940s. On the of the lube oil for each full circuit the sodium, which may be either a lubri- strength of its usefulness in maintaining oil makes through the standard full- cant additive or a sign of seawater locomotives, oil analysis was embraced flow filter.) It must be specifically intrusion; and potassium, which is by the U.S. Navy in the 1950s to moni- tailored to detect the contaminants tor and prevent failures in then-new jet and potential failings peculiar to airplane engines exposed to the harsh extended oil drain intervals. More on conditions on aircraft carriers. Rolls this below. Royce, the British aircraft engine manu- The goal of establishing an oil- facturer, also adopted oil analysis as a analysis program is to be predictive, maintenance protocol at about the preventive, and proactive in ways that same time. simple scheduled-based maintenance Programs like these spawned a pro- doesn’t allow. However, this more cess known as condition-based main- technically sophisticated maintenance tenance (CBM), which augmented or protocol requires vigilance, commit- replaced rigidly scheduled mainte- ment, and a specialized understanding nance by providing service and to read the early warnings in regular repairs when analysis indicated they oil-testing data. were needed, rather than on an hourly or calendar-based system. Wear Metals, Additives, While a single sample may reveal and Contaminants some impending catastrophic fault— Contamination of engine, transmis- high levels of glycol, for instance, sion, or hydraulic oil with small often indicate a leaking head gasket particles of metal, dust, soot, or or cracked head or block—more liquids alters the oil’s viscosity often, taking multiple samples over time reveals a gradual trend toward a problem looming far off in the future and allows plenty of opportunity for corrective action. Such trends are Top right—Aluminum from this most effectively identified by compar- severely scuffed piston was ing a used-oil sample with an unused deposited on the cylinder wall sample of the same brand, grade, and (right). Long before the weight of oil and with results from catastrophic failure required a previous used samples from the sub- complete engine rebuild, an oil ject mechanical system. A solitary analysis report could have sample, while undeniably advanta- identied the problem in time geous in its own right, supplies the to take corrective measures. JUNE/JULY 2013 63 The tan deposit on this symptoms of oxidation and nitration, valve is the result of two chemical changes detrimental to coolant leaking into the oil quality. Both these molecular-level cylinder. Oil analysis deteriorations are caused by age and alerted the user to operating conditions. the presence of glycol Oxidation is accelerated by exces- before symptoms sive engine heat (if an engine over- more serious than heats, its oil and coolant should be some coolant loss changed as soon as possible). manifested. Oxidation can increase oil viscosity and impair the performance of oil additives intended to maintain an acid- neutralizing reserve. A drop in the either a coolant additive (indicat- are fouled or not properly matched to total base number (TBN) indicates ing a coolant leak into the oil) or an their engines; restricted air filters; increased acidity and that the oil is airborne contaminant. excessive back-pressure, a common “worn out.” The oxidation rate of oil Multi-source metals include molyb- result of improperly designed exhaust doubles with every 18°F (10.8°C) denum, antimony, manganese, lith- systems; and worn piston rings, which increase in temperature. Typical ideal ium, and boron, some of which are facilitate the entry of soot into the engine-oil temperatures range from additives found in lube oil and crankcase. 180°F to 220°F (82°C to 104°C). hydraulic fluid, while others are Similarly, diesel fuel in the lube oil Nitration is an indication of exces- coolant inhibitors or alloying agents can wreak havoc by reducing oil vis- sive blowby, which is typically caused with other metals. Metals that are cosity. Its presence in a sample sug- by worn piston rings, cylinder walls, commonly added to lube oil to gests a malfunctioning injector or or both. It’s also an indication of the enhance or fortify its properties injectors; a leaking injection pump presence of nitric acid, which pro- include magnesium, a detergent/ shaft seal; a leaking low-pressure lift motes oxidation. Increased nitration dispersant; calcium, also a detergent; pump; excessive cool running, which elevates the oil’s total acid