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Condition-Based Maintenance Pinpoints Four Biggest Engine Killers

Diesel engines are one of the most expensive pieces of equipment for a maintenance manager to replace—they are also one of the easiest to save. Making fluid analysis part of your maintenance strategy can identify the four biggest engine killers before they cause major problems, saving you thousands of dollars a year in unnecessary maintenance and replacement costs.

Why waste valuable wrench time when an effective fluid analysis program can maximize the resources you have. Find out how a maintenance strategy based on engine and lubricant condition will minimize failures and save valuable time and money by:

• Identifying contamination
• Identifying wear and its possible sources
• Moving your maintenance practices toward a more condition-based approach

Today's maintenance manager is constantly challenged to do more with less. If fluid analysis can save just one engine, you've paid for the cost of an effective program and it will change the way you think about maintenance and reliability.

The Four Biggest Engine Killers

Killer #1 - Dirt

Diesel engines in mining and construction applications as well as over-the-road transportation fleets are highly susceptible to dirt ingression. Whether it's a short haul, heavy load haul truck or a long haul OTR trailer, dirt is a highly abrasive contaminant that can significantly shorten or end engine life.

Oil is most often contaminated by dirt when there are issues with the air intake system - it's either been improperly installed or has failed. As a result, upper end components - pistons, liners, rings and valves - begin to wear first. This is evident in elevated ICP results for iron, chromium, nickel and aluminum. Elevated levels of lead, copper and tin indicate bearing wear. View Report (255975)

Fluid analysis identifies dirt by the presence of silicon or aluminum. The key here is to establish appropriate alarm limits for flagging these elements as many lubricants typically contain 3-15 ppm silicon as an anti-foam additive. Providing new lube references before you begin testing used oil samples gives the laboratory a baseline to compare them to and ensures that flagged results are indeed cause for maintenance action. When silicon levels exceed these pre-set limits and there are also increasing levels of iron, lead, copper and tin, you will know there is enough dirt circulating through the system to damage engine components. Taking maintenance action early allows you to avoid catastrophic failure later.

Killer #2 - Fuel Dilution

Fuel dilution is the amount of raw, unburned fuel circulating within the engine. Not all of the diesel fuel injected to the cylinder is expended during the combustion process. Inevitably, some works its way past the piston rings and into the crankcase where it “dilutes” or mixes with the engine's lubricating oil - the result is fuel dilution.

More than 14% of the 383,789 engine samples POLARIS Laboratories® has tested this year had fuel dilution levels high enough to flag. Not only does fuel dilution decrease an engine oil's viscosity and lubricity, it can alter the performance of anti-wear additives which are designed to form a protective layer on metallic surfaces that guards against wear. Biodiesel blends also attract these additives leaving less available to protect engine metals. The resulting friction-related wear causes immediate engine component damage and can lead to premature engine failure if not detected quickly. Taking action at initial severity levels can greatly reduce unnecessary repairs and replacement costs.

POLARIS Laboratories® confirms fuel dilution by gas chromatography based on a variance in the oil's viscosity. GC separates the components of a mixture from one another by vaporizing the sample into a carrier gas stream that is passed through a column containing a substance that selectively adsorbs then releases the components to be measured.

Because a #2 diesel fuel typically has a viscosity of around 1.7-2.1 cSt at 40°C, which is thinner than a typical 15W40 engine oil with a viscosity of around 14.7 cSt at 100°C, fuel dilution decreases the engine oil's viscosity. When the oil's viscosity varies by more than one (1) cSt from the known starting viscosity of the oil when new, POLARIS Laboratories® confirms fuel dilution by the new GC method reporting the result as we do currently - as percent by volume. However, if lubricant grade is not included with the sample, fuel dilution will be confirmed by GC if viscosity is below 13.3 cSt for a diesel engine oil and below 9.8 cSt for a gasoline engine oil. If viscosity is above the oil's mid-point for the grade, fuel dilution will be reported as <1.0%. View Report (618278)

Killer #3 - Soot

Fuel in a diesel engine is injected during the compression stroke. The high pressure ignites the fuel immediately allowing it no time to properly mix with air. Combustion is incomplete and soot is created. Engine designs of the past expelled most of the soot created by inefficient fuel combustion through the exhaust, but EGR engines re-circulate exhaust gases back into the cylinder at a lower temperature to reduce NOx emission. Retarding ignition timing and reducing the amount of oxygen in the cylinder produces less NOx but inhibits combustion and creates excess soot.

If not adequately dispersed within the oil, soot particles begin to agglomerate, or gather into clusters increasing viscosity and allowing deposits to form on metal surfaces. Thick, sooty oil can plug filters and increase operating temperatures which can cause lubrication starvation and ultimately, metal on metal contact. The soot then becomes a harsh abrasive that accelerates wear in cylinder liners, rings, piston skirts, journal bearings and valve trains. View Report (527561)

Killer #4 - Coolant

In 2009 in just one transportation fleet, POLARIS Laboratories® identified 233 coolant leaks at a severity 3 or 4 - more than 6% of the total number of samples submitted. Elemental Analysis by ICP (inductively-coupled plasma) detects any sodium or potassium - carrier salts for coolant inhibitors -present in the oil, which may indicate the beginning stages of a coolant leak. If copper, lead and/or tin are also present, chances are bearing wear has begun. View Report (185688)

If testing identifies a coolant leak, correcting the problem at a Severity 1 or 2 can prevent premature failure. You may only have to replace a leaking oil cooler or a damaged head gasket or EGR valve gasket. But if the leak were allowed to progress, the coolant would eventually attack the softer metals of the engine such as the copper and lead in main and rod bearings. Now you're not only replacing the oil cooler and gaskets but the bearings and possibly the crankshaft as well.

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